Infectious Disease Clinical Training Manual

Small Hospital/Clinic Reference Guide

---

1. PRINCIPLES OF INFECTIOUS DISEASE

Microbial Classification and Characteristics

BACTERIA

• Prokaryotes, divide by binary fission, 0.5-5 µm diameter
• Gram-positive (thicker peptidoglycan, purple stain): Staphylococci, Streptococci, Clostridia, Listeria, Bacillus
• Gram-negative (thin peptidoglycan, pink stain): E. coli, Klebsiella, Pseudomonas, Enterobacteriaceae, Neisseria, Vibrio
• Acid-fast (waxy cell wall): Mycobacterium tuberculosis, M. avium, Nocardia
• Atypical (minimal/no cell wall): Mycoplasma, Chlamydia, Legionella

VIRUSES

• Obligate intracellular parasites, contain RNA or DNA core surrounded by protein coat and lipid envelope
• Enveloped (susceptible to alcohol, soap, drying): influenza, measles, mumps, varicella-zoster, CMV, HIV, SARS-CoV-2
• Non-enveloped (resistant to environmental stress, drying): poliovirus, adenovirus, rotavirus, norovirus, rhinovirus

FUNGI

• Eukaryotes with cell wall (chitin/glucans), reproduce by spores
• Yeasts (C. albicans, C. auris, Cryptococcus): single-cell, reproduce by budding
• Molds (Aspergillus, Mucor, Rhizopus): filamentous, reproduce by spores
• Dimorphic (H. capsulatum, C. immitis, B. dermatitidis): yeast form in body, mold form in environment

PARASITES

• Protozoa (single-cell): Plasmodium (malaria), Toxoplasma, Giardia, Entamoeba, Cryptosporidium
• Helminths (worms): Roundworms (Ascaris, hookworms), tapeworms (Taenia), flukes (Schistosoma)
• Ectoparasites: Scabies mite, head/body lice

Host Defenses and Pathophysiology

Innate Immunity

• Physical barriers: epithelium, mucus, cilia, stomach acid, normal flora
• Complement cascade: C1-C9, MAC (membrane attack complex), opsonization, inflammation
• Phagocytes: neutrophils (PMN, kill via ROS and granules), macrophages, dendritic cells
• Pattern recognition: TLRs (toll-like receptors), NOD-like receptors, lectins
• Inflammatory mediators: TNF, IL-1, IL-6, chemokines

Adaptive Immunity

• T cells: CD8+ cytotoxic (kill infected cells), CD4+ helper (coordinate immune response, IL-2/IFN-γ production)
• B cells: produce antibodies (IgM, IgG, IgA, IgE), memory B cells
• Antibody functions: opsonization, neutralization, complement fixation, ADCC
• Mucosal immunity: IgA secretion, GALT (gut-associated lymphoid tissue), MALT

Virulence Factors

• Adherence: pili, fimbriae, adhesins (e.g., pneumococcal PspA)
• Invasion: IgA protease, hyaluronidase, collagenase, invasins
• Toxins: exotoxins (diphtheria, tetanus, cholera), enterotoxins, endotoxins (LPS)
• Immune evasion: capsule (antiphagocytic), antigenic variation, molecular mimicry
• Biofilms: matrix of EPS, reduced antibiotic penetration, persister cells

Antibiotic Mechanisms of Action and Resistance

MOA Classes

Cell Wall Inhibitors

• Beta-lactams (penicillins, cephalosporins, carbapenems): inhibit transpeptidase → PBP2a/3 inactivation → cell wall lysis
• Vancomycin: inhibits D-Ala-D-Ala cross-linking
• Action: bactericidal

Protein Synthesis Inhibitors

• 30S subunit: aminoglycosides (streptomycin, gentamicin), tetracyclines, chloramphenicol
• 50S subunit: macrolides (erythromycin), linezolid, clindamycin
• Action: bacteriostatic (except aminoglycosides = bactericidal)

Nucleic Acid Inhibitors

• DNA gyrase inhibitors: fluoroquinolones (cipro, levofloxacin)
• Topoisomerase IV inhibitors: fluoroquinolones (particularly in Gram-positive)
• RNA polymerase inhibitors: rifampin
• Antimetabolites: TMP-SMX, metronidazole (anaerobe DNA damage)
• Action: bactericidal (FQ, rifampin) or bacteriostatic (TMP-SMX)

Metabolic Inhibitors

• Metronidazole: forms DNA adducts in anaerobes
• Sulfonamides: PABA competitive inhibition

Resistance Mechanisms

• Enzymatic inactivation: β-lactamases (TEM, SHV, CTX-M), aminoglycoside modifying enzymes (APH, AAC, ANT)
• Target modification: PBP alterations (MRSA, pneumococci), ribosomal mutations (macrolide-resistant Streptococcus), gyrA/topoisomerase mutations (FQ-resistant)
• Reduced uptake: altered porins (β-lactam, FQ resistance), efflux pumps (MRSA, P. aeruginosa, A. baumannii)
• Production of alternative pathways: thyA mutations (TMP-SMX resistance), folate production (sulfonamide resistance)
• Horizontal gene transfer: plasmids, transposons, integrons (disseminate resistance genes)

Common Resistance Patterns

• MRSA: mecA gene → altered PBPs (PBP2a), requires vancomycin/linezolid
• ESBL: CTX-M, SHV, TEM genes → 3rd-gen cephalosporin resistance, treated with carbapenems
• CRE (carbapenem-resistant Enterobacteriaceae): KPC, NDM, OXA carbapenemases, polymyxins/colistin options
• VRE (vancomycin-resistant Enterococcus): vanA/vanB operons, requires linezolid/daptomycin
• MDR Pseudomonas/Acinetobacter: multiple efflux systems, often requires combination therapy
• MDR Tuberculosis: rpoB mutations (isoniazid, rifampin), inhA overexpression (isoniazid)

Empiric vs Targeted Therapy

Empiric Therapy Principles

• Start immediately in sepsis/severe illness (don’t wait for culture)
• Broaden spectrum initially: cover Gram+, Gram-, and anaerobes based on source
• Culture first, then antibiotics (blood, CSF, urine, wound)
• Use local resistance patterns and patient risk factors
• Duration: shift to targeted therapy once organism/sensitivities known (typically 48-72h)

De-escalation Strategy

• Review cultures daily; narrow spectrum when susceptibilities return
• Reduce to single agent when possible (monotherapy vs combination therapy)
• Reduce duration to shortest effective course (most infections 7-14 days, not 21+)
• Consider oral step-down when clinically improved and tolerating PO

Targeted Therapy

• Culture-directed: use most narrow-spectrum, least toxic, most cost-effective option
• Source control and organism identification drive selection
• Single agent preferred (except bacteremia/endocarditis, sepsis requiring combination)
• Adequate CNS penetration if meningitis (vancomycin, 3rd-gen cephalosporins, fluoroquinolones)

Culture Interpretation and Laboratory Diagnosis

Specimen Collection

• Timing: cultures before antibiotics in all sepsis/serious infection
• Volume: blood (10mL per bottle, 2-3 sets), CSF (10mL minimum), urine (midstream, >10⁵ CFU/mL significant)
• Contamination prevention: skin antisepsis (chlorhexidine > povidone-iodine), sterile containers
• Transport: no delay, keep cold for respiratory specimens

Culture Interpretation

• Single organism from sterile site (blood, CSF, synovial fluid) = pathogenic
• Coagulase-negative Staph, diphtheroids from blood = likely contaminant (unless immunocompromised, prosthetic valve)
• Multiple organisms from single culture = likely contamination
• Culture results + clinical context + gram stain inform treatment

Gram Stain Morphology

• Gram+ cocci in clusters: Staphylococcus
• Gram+ cocci in chains: Streptococcus
• Gram+ rods: Bacillus, Clostridium, Listeria (may appear coccobacillary)
• Gram- rods (enteric): Enterobacteriaceae, E. coli, Klebsiella, Proteus, Serratia
• Gram- rods (non-fermenting): Pseudomonas aeruginosa, Acinetobacter baumannii
• Gram- cocci: Neisseria (kidney bean-shaped, intracellular in PMNs)
• Curved Gram- rod: Vibrio, Campylobacter
• Branching filaments: Nocardia, Actinomyces

Diagnostic Modalities

• Blood cultures: gold standard for bacteremia, may take 48-72h, need 2-3 sets
• Gram stain: rapid (30 min), guides empiric therapy
• PCR: rapid, organism/resistance gene identification, improved molecular diagnostics
• Antigen detection: strep throat (rapid), urinary antigens (Streptococcus, Legionella), serology
• Viral cultures/NAATs: respiratory panels (multiplex RT-PCR for influenza, RSV, SARS-CoV-2, rhinovirus, parainfluenza, MPV, adenovirus, enterovirus)
• Susceptibility testing: disk diffusion (Kirby-Bauer), E-test, automated systems (VITEK, Phoenix), guide targeted therapy

---

2. ANTIBIOTIC GUIDE

PENICILLINS

Spectrum: Gram+, some Gram-, respiratory anaerobes; narrow spectrum

Mechanism: Beta-lactam cell wall inhibitor (bactericidal)

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Penicillin V	250-500mg PO QID	12.5-25 mg/kg QID (max 250mg/dose)	Strep throat, rheumatic fever prophylaxis
Penicillin G	2-4MU IV Q4-6H	25,000-40,000 units/kg Q4-6H	Meningitis, syphilis, severe infections
Amoxicillin	500-1000mg PO TID	25-45 mg/kg/day divided TID	Otitis media, strep throat, community UTI
Ampicillin	500mg-1g IV/IM Q4-6H	25-50 mg/kg Q4-6H	Listeria meningitis, ampicillin-susceptible Enterobacteriaceae
Amoxicillin-clavulanate	875/125mg PO BID	22.5/3.125 mg/kg BID	Skin infections, otitis media with Staph, H. influenzae

Indications: Streptococcal infections, penicillin-susceptible pneumococcus, syphilis, rheumatic fever prophylaxis, endocarditis (streptococci)

Side Effects: Rash (5-8%, nonallergic in many), anaphylaxis (0.1% true penicillin allergy), C. difficile, seizures (high-dose penicillin G CNS), drug fever

Notes: Cross-reactivity with cephalosporins ~2% in non-anaphylactic allergy; avoid if immediate hypersensitivity reaction

CEPHALOSPORINS

Spectrum: Gram+ and Gram- coverage; spectrum increases by generation

Mechanism: Beta-lactam (cell wall) with greater stability against many beta-lactamases

1st Generation (primarily Gram+, some Gram-)

Drug	Adult Dose	Pediatric Dose	Indication
Cephalexin	500mg-1g PO QID	25-50 mg/kg/day QID	Skin/soft tissue, UTI prophylaxis, susceptible strep/Staph
Cefazolin	1-2g IV Q6-8H	25-100 mg/kg/day Q6-8H	Surgical prophylaxis, skin/soft tissue, susceptible Gram+ infections

2nd Generation (Gram+ + increased Gram-, some anaerobic)

Drug	Adult Dose	Pediatric Dose	Indication
Cefuroxime	750mg-1.5g IV Q8H	50-100 mg/kg/day Q8H	Meningitis (better CNS penetration than 3rd gen cephs), Lyme disease, serious respiratory infections
Cefoxitin	1-2g IV Q4-6H	80-160 mg/kg/day Q4-6H	Anaerobic coverage (abdominal, gynecologic), intra-abdominal surgery
Cefotetan	1-2g IV Q12H	40-80 mg/kg/day Q12H	Surgical prophylaxis, anaerobic infections

3rd Generation (excellent Gram-, variable Gram+, CNS penetration)

Drug	Adult Dose	Pediatric Dose	Indication
Ceftriaxone	1-2g IV/IM Q12H	50-100 mg/kg/day Q12H (max 4g/day)	Meningitis, Gram- infections, gonorrhea, empiric sepsis, Lyme disease
Cefotaxime	1-2g IV Q4-6H	100-200 mg/kg/day Q4-8H	Meningitis (similar to ceftriaxone), sepsis, CNS infections
Ceftazidime	1-2g IV Q8H	30-50 mg/kg Q8H	Pseudomonas aeruginosa, CRE (less effective, use with caution), febrile neutropenia

4th Generation (Gram+ + excellent Gram- including Pseudomonas, anaerobes)

Drug	Adult Dose	Pediatric Dose	Indication
Cefepime	1-2g IV Q8-12H	50 mg/kg Q8-12H	Pseudomonas, febrile neutropenia, serious aerobic Gram- infections, alternatives to carbapenems

Indications by Class:

• 1st gen: community UTI, skin/soft tissue, surgical prophylaxis
• 2nd gen: serious respiratory infections, meningitis (cefuroxime), anaerobic mixed infections
• 3rd gen: empiric sepsis, Gram- meningitis, serious Gram- infections
• 4th gen: Pseudomonas, resistant Gram- bacteria, febrile neutropenia

Side Effects: Rash (non-allergic, 1-3%), anaphylaxis (rare, 0.001-0.1%), C. difficile, hypoprothrombinemia (3rd/4th gen), false positive Coombs test

Notes: 1-2% cross-reactivity with penicillins in non-severe allergy; higher risk in 1st gen cephalosporins; avoid in immediate hypersensitivity

FLUOROQUINOLONES

Spectrum: Broad Gram+/Gram-, atypical organisms (Legionella, Mycoplasma), anaerobic coverage variable

Mechanism: DNA gyrase and topoisomerase IV inhibition → DNA damage and cell death (bactericidal)

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Ciprofloxacin	500-750mg PO BID; 400mg IV Q12H	20-30 mg/kg/day BID (age <18 limited use)	Gram-, UTI, bacterial gastroenteritis, CF respiratory, Pseudomonas UTI
Levofloxacin	500-750mg PO/IV QD	10-20 mg/kg/day QD	Community pneumonia, UTI, prostatitis, atypical organisms
Moxifloxacin	400mg PO/IV QD	Not routinely used in children	CAP with atypical coverage, anaerobic coverage superior to other FQs
Ofloxacin	300-400mg PO/IV BID	5-10 mg/kg BID	UTI, prostatitis, respiratory infections

Indications: Gram- UTI, travelers’ diarrhea, COPD exacerbations, community-acquired pneumonia (levofloxacin, moxifloxacin), Pseudomonas aeruginosa UTI, atypical respiratory infections, cost-effective oral therapy for susceptible Gram- infections

Side Effects: Tendinitis/tendon rupture (especially Achilles, risk with age >60, steroids, renal failure), QT prolongation (especially moxifloxacin), CNS effects (dizziness, insomnia, seizures in epilepsy), photosensitivity, C. difficile, dysglycemia

Resistance: gyrA/topoisomerase mutations common in E. coli (40-50% resistance in some regions), Pseudomonas efflux pumps, emerging resistance in Gram-negative bacteria

Notes: Avoid in pregnancy/nursing; avoid in children except serious infections (cartilage effects not clinically significant in humans); QT risk with baseline prolongation

MACROLIDES

Spectrum: Gram+, atypical (Mycoplasma, Chlamydia, Legionella), some anaerobes; poor Gram-

Mechanism: 50S ribosomal subunit inhibition (bacteriostatic)

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Erythromycin	500mg-1g PO QID; 500mg IV Q6H	12.5 mg/kg QID	Pertussis, atypical CAP, enterococcal endocarditis prophylaxis
Azithromycin	500mg day 1, then 250mg QD (5 days); 500mg IV QD	10 mg/kg day 1, 5 mg/kg QD (3-5 days)	Atypical pneumonia, STIs (Chlamydia), Mycobacterium avium prophylaxis, CAP
Clarithromycin	500mg PO BID; 500mg IV Q12H	7.5 mg/kg BID	MAC prophylaxis, Helicobacter pylori, atypical pneumonia, Mycobacterium avium

Indications: Atypical CAP (Mycoplasma, Chlamydia, Legionella), Chlamydia trachomatis, MAC prophylaxis in AIDS, Helicobacter pylori eradication, pertussis, G. trachomatis urethritis

Side Effects: GI upset (nausea, diarrhea), QT prolongation (especially erythromycin IV, azithromycin with cardiac disease), hepatotoxicity (rare), drug interactions (CYP3A4 inhibition), C. difficile

Resistance: Ribosomal methylation (erm genes), efflux pumps; increasing resistance in Streptococcus and Staphylococcus

Notes: Erythromycin has most QT risk; azithromycin Z-pack (5-day therapy) convenient for outpatient; interactions with statins, warfarin, digoxin

TETRACYCLINES

Spectrum: Broad, including atypical organisms (Mycoplasma, Chlamydia, Rickettsiae), anaerobes, MRSA, Spirochetes

Mechanism: 30S ribosomal subunit inhibition (bacteriostatic)

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Doxycycline	100mg PO/IV BID	>8 years: 2.2 mg/kg BID (max 100mg/dose)	Lyme disease, atypical pneumonia, Chlamydia, anaerobes, rickettsial diseases, MRSA, acne
Tetracycline	500mg PO QID	>8 years: 25-50 mg/kg/day QID	Similar spectrum; more GI upset than doxycycline
Minocycline	100mg PO BID	>8 years: 4 mg/kg initially, then 2 mg/kg BID	Similar indications; better CNS penetration; photosensitivity risk

Indications: Lyme disease, Rocky Mountain spotted fever, atypical pneumonia, Chlamydia trachomatis/psittaci, anaerobes, MRSA skin infection, spirochetes (syphilis), Q fever, Brucella

Side Effects: GI upset, photosensitivity (especially doxycycline), esophageal ulceration (take with water, upright position), teeth discoloration and enamel dysplasia (<8 years, pregnancy), hepatotoxicity (expired tetracycline), pseudotumor cerebri, C. difficile

Notes: Avoid in pregnancy; avoid in children <8 years except critical circumstances; doxycycline is most commonly used (better absorption, less frequent dosing, fewer GI effects); take on empty stomach or with non-dairy food

AMINOGLYCOSIDES

Spectrum: Gram- rods, Gram+ and Gram- cocci (synergistic with beta-lactams), some anaerobes; poor Gram+ monotherapy

Mechanism: 30S ribosomal subunit inhibition; bactericidal (oxygen-dependent uptake)

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Gentamicin	5-7 mg/kg IV QD (or 1.5-2 mg/kg IV Q8H); levels monitored	2.5 mg/kg Q8H (or 7.5 mg/kg QD), TDM	Gram- sepsis (with beta-lactam), Gram+ endocarditis (with PCN/ceph), synergy
Tobramycin	5-7 mg/kg IV QD; levels monitored	2.5 mg/kg Q8H	Similar to gentamicin; preferred in cystic fibrosis for Pseudomonas
Amikacin	15-20 mg/kg IV QD (or 5-7.5 mg/kg Q8H); levels monitored	7.5 mg/kg Q8H (or 15-20 mg/kg QD)	Resistant Gram-, Nocardia; less ototoxicity than gentamicin

Indications: Gram- sepsis (always with beta-lactam), endocarditis (synergy with penicillin/vancomycin for streptococci/Staphylococcus), febrile neutropenia, seriously ill patients with Gram- infections, Pseudomonas cystic fibrosis

Side Effects: Nephrotoxicity (dose, duration, volume depletion, concurrent nephrotoxic agents), ototoxicity (permanent, dose and duration, higher with loop diuretics), vestibular dysfunction, neuromuscular blockade (rare), anaphylaxis (rare)

Pharmacokinetics: Require therapeutic drug monitoring (TDM); peak levels: gentamicin/tobramycin 5-10 µg/mL, amikacin 15-30 µg/mL; trough <1 µg/mL (gentamicin/tobramycin) or <4-5 µg/mL (amikacin)

Notes: Require renal dose adjustment; always use with beta-lactam for coverage; once-daily dosing preferred (less nephrotoxicity); synergy with cell wall inhibitors

CARBAPENEMS

Spectrum: Broadest beta-lactam spectrum; Gram+/Gram-/anaerobes including CRE-producing ESBL

Mechanism: Beta-lactam (cell wall) with high stability against most beta-lactamases

Key Drugs and Dosing

Drug	Adult Dose	Pediatric Dose	Indication
Meropenem	500mg-1g IV Q8H	20-40 mg/kg Q8H	Meningitis, serious polymicrobial infections, CRE with resistance, febrile neutropenia
Imipenem-cilastatin	500mg IV Q6H (cilastatin prevents renal breakdown)	15-25 mg/kg Q6H	Similar spectrum; more seizure risk than meropenem; less meningitis use
Ertapenem	1g IV/IM QD	15 mg/kg BID (if >3 months)	Community infections with ESBL, intra-abdominal/gynecologic infections, complicated skin infections

Indications: Suspected ESBL Enterobacteriaceae, serious polymicrobial infections, meningitis with resistant Gram+, CRE (limited carbapenem-susceptible strains), febrile neutropenia when beta-lactam allergy unlikely, serious hospital-acquired infections

Side Effects: Rash, nausea, diarrhea, seizures (especially imipenem, high doses, renal failure), C. difficile, hypersensitivity (cross-reactivity with penicillin ~1-3%), phlebitis (IV site)

Resistance: Carbapenemases (KPC, NDM, OXA, VIM) confer broad resistance; test for carbapenem susceptibility

Notes: Reserve for serious infections or documented resistance; avoid overuse; imipenem requires cilastatin co-dosing; seizure risk increases with elevated drug levels

VANCOMYCIN and LINEZOLID

Spectrum: Gram+ (including MRSA, resistant streptococci), some Gram- (limited), anaerobes (vancomycin)

Mechanism: Vancomycin inhibits D-Ala-D-Ala transpeptidase (different site from beta-lactams); Linezolid inhibits 50S ribosome (bacteriostatic)

VANCOMYCIN

Indication	Adult Dose	Pediatric Dose
Endocarditis	15-20 mg/kg IV Q8-12H (target trough 15-20 µg/mL)	10-15 mg/kg Q6-8H
Meningitis	15-20 mg/kg IV Q4-6H (higher dosing, target trough 15-20 µg/mL)	10-20 mg/kg Q6H
MRSA infection	15-20 mg/kg IV Q8-12H (target trough 10-15 µg/mL)	10-15 mg/kg Q6-8H
C. difficile	125mg PO QID x 10 days	5-10 mg/kg PO QID

Indications: MRSA, ampicillin-resistant Listeria (with gentamicin), penicillin-resistant pneumococcus, beta-lactam allergy with Gram+ infection, endocarditis (MRSA, resistant streptococci), C. difficile (oral form)

Side Effects: Nephrotoxicity (require renal dosing, monitor creatinine), ototoxicity (especially with aminoglycosides, high trough levels), “red man syndrome” (infusion reaction, flushing, chills; prevent with premedication—diphenhydramine, acetaminophen, slow infusion), phlebitis, thrombophlebitis

Pharmacokinetics: TDM essential; trough levels 10-20 µg/mL; renal clearance dependent; monitor renal function, Cr

LINEZOLID

Indication	Adult Dose	Pediatric Dose
MRSA, VRE	600mg PO/IV BID	10 mg/kg BID
Pneumonia/complicated skin	600mg PO/IV BID	10 mg/kg BID

Indications: MRSA with poor venous access (oral availability), VRE, resistant Gram+ when vancomycin intolerant, excellent bone penetration (osteomyelitis), CNS penetration

Side Effects: Bone marrow suppression (thrombocytopenia, neutropenia; monitor CBC), serotonin syndrome (with other serotonergics), peripheral/optic neuropathy (prolonged use >2 weeks), lactic acidosis (rare), C. difficile

Notes: Expensive; monitor CBC; avoid with SSRIs/SNRIs if possible; reversible myelosuppression; good for prosthetic infections and CNS penetration

METRONIDAZOLE

Spectrum: Anaerobes (Bacteroides, Clostridium, Prevotella), Gram+ anaerobes, protozoa (Giardia, Entamoeba, Trichomonas)

Mechanism: Nitroimidazole forms DNA adducts in anaerobic organisms (bactericidal)

Dosing

Indication	Adult Dose	Pediatric Dose
Anaerobic infection	500mg IV/PO Q6-8H	7.5 mg/kg Q6-8H
Clostridium difficile	500mg PO QID x 10 days (or vancomycin preferred)	7.5 mg/kg QID
Giardia	250mg PO TID x 5-7 days	5 mg/kg TID
Trichomonas	2g PO single dose (or 250mg TID x 7 days)	15-25 mg/kg single dose

Indications: Anaerobic infections (intra-abdominal, gynecologic, CNS), mixed aerobic-anaerobic infections, C. difficile (second-line to vancomycin), Giardia, Trichomonas, Entamoeba histolytica

Side Effects: Metallic taste, nausea, disulfiram-like reaction with alcohol, peripheral neuropathy (prolonged use), CNS effects (seizures, encephalopathy), dark urine, photosensitivity, pseudomembranous colitis (paradoxical)

Notes: Penetrates abscess well; good CNS penetration; avoid alcohol; peripheral neuropathy risk with prolonged therapy (>2 weeks)

TRIMETHOPRIM-SULFAMETHOXAZOLE (TMP-SMX)

Spectrum: Gram+/Gram-, including MRSA, Nocardia, Pneumocystis jirovecii, Toxoplasma, Cyclospora, Isospora

Mechanism: Sequential folate pathway inhibition (DHFR and DHPS inhibition); bactericidal

Dosing

Indication	Adult Dose	Pediatric Dose
UTI	1 DS tablet PO BID x 3 days (acute)	4-6 mg/kg (TMP component) BID
Community infection	1-2 DS tablets PO BID	6-12 mg/kg (TMP component)
PCP prophylaxis	1 DS tablet QD or TID per week	150 mg/m² (TMP component) QD
PCP treatment	15-20 mg/kg (TMP) IV Q6H	15-20 mg/kg Q6H
Toxoplasma prophylaxis	1 DS tablet QD	150 mg/m² QD

Indications: UTI (first-line in susceptible regions), MRSA skin infection, Nocardia, Toxoplasma prophylaxis/treatment in AIDS, Pneumocystis prophylaxis and treatment, Listeria (if penicillin allergic), traveler’s diarrhea

Side Effects: Rash (5-8%, nonallergic), hyperkalemia (especially with renal disease, ACE inhibitors), acute kidney injury (volume depletion), hepatotoxicity, bone marrow suppression (rare), SJS/TEN (severe, <0.5%), photosensitivity, C. difficile

Resistance: DHFR mutations (TMP resistance), DHPS mutations (sulfonamide resistance); emerging in E. coli (20-40% in many regions)

Notes: DS = double-strength (160/800 mg); SS = single-strength (80/400 mg); monitor renal function and K+; caution with sulfa allergy (cross-reactivity 3%)

---

3. INFECTIONS BY SYSTEM

RESPIRATORY INFECTIONS

Community-Acquired Pneumonia (CAP)

Pathogens by severity:

• Outpatient: S. pneumoniae, H. influenzae, Mycoplasma, Chlamydia, respiratory viruses
• Hospitalized: add Gram- (E. coli, Klebsiella, Pseudomonas in severe/ICU)
• Aspiration risk: anaerobes (Peptostreptococcus, Prevotella, Fusobacterium)

Empiric therapy:

• Outpatient (mild-moderate): Amoxicillin 1g TID OR Doxycycline 100mg BID OR Azithromycin 500mg day 1, 250mg QD (reassess in 48-72h)
• Hospitalized: Ceftriaxone 1g IV Q12H + Azithromycin 500mg IV QD OR Levofloxacin 750mg IV QD (monotherapy if stable)
• ICU/severe: Ceftriaxone or Cefotaxime 1-2g IV Q12H + Vancomycin 15mg/kg IV Q8-12H + Levofloxacin 750mg IV QD (Pseudomonas coverage)
• Pediatric (outpatient): Amoxicillin 25-45 mg/kg/day TID OR Azithromycin 10 mg/kg day 1, 5 mg/kg QD

Duration: 5-7 days (if clinical improvement), can be longer in severe disease

Influenza

• Pathogens: Influenza A/B (H1N1, H3N2, Victoria, Yamagata lineages)
• Treatment: Oseltamivir (Tamiflu) 75mg PO BID x 5 days if started within 48h (reduces duration 1 day); pediatric oseltamivir by weight
• Prophylaxis: 75mg PO QD x 10 days post-exposure (contacts, residents in congregate living)
• Note: Antivirals reduce hospitalization/mortality in severe disease; circulating resistance rare

Tuberculosis (TB)

Diagnosis: AFB sputum smear (rapid but insensitive), mycobacterial culture (gold standard, 2-8 weeks), TB IGRA or TST, CXR (apical infiltrate, cavitation)

Initial Treatment (Drug-Sensitive TB):

• Intensive phase (2 months): Isoniazid 5 mg/kg (max 300mg) + Rifampin 10 mg/kg (max 600mg) + Pyrazinamide 25 mg/kg (max 2g) + Ethambutol 15-25 mg/kg QD
• Continuation phase (4 months): Isoniazid + Rifampin QD or twice weekly
• Pediatric: Isoniazid 10-15 mg/kg QD, Rifampin 15-20 mg/kg QD, Pyrazinamide 30-40 mg/kg QD, Ethambutol 15-25 mg/kg QD

MDR-TB (resistant to INH, RIF):

• Requires 2nd-line agents (fluoroquinolone + injectable [amikacin/streptomycin/capreomycin] + bedaquiline or linezolid)
• Duration: 20+ months, specialized TB centers, directly-observed therapy (DOT)
• Diagnosis: drug susceptibility testing (DST) required

Latent TB:

• Isoniazid 300mg QD x 9 months OR Rifampin 600mg QD x 4 months
• Pediatric: Isoniazid 10-15 mg/kg QD x 9 months

Special Considerations: Vitamin B6 supplementation (isoniazid neuropathy prevention), monitor LFTs (TB drugs hepatotoxic), DOT compliance critical

Pertussis

• Agent: Bordetella pertussis
• Diagnosis: PCR respiratory secretions (early), serology (late)
• Treatment: Azithromycin 500mg day 1, then 250mg QD x 4 days (shortens respiratory shedding if given early)
• Pediatric: 10 mg/kg day 1, 5 mg/kg QD (3-5 days)
• Prophylaxis: Azithromycin for contacts
• Note: Antibiotic does not shorten paroxysmal cough phase

---

URINARY TRACT INFECTIONS (UTI)

Acute Uncomplicated Cystitis (Acute Urethritis)

Pathogens: E. coli (85-90%), S. saprophyticus (5-10%), Klebsiella, Proteus, Enterococcus

Empiric therapy:

• Nitrofurantoin 100mg PO BID x 5-7 days (preferred in many regions) OR
• TMP-SMX 1 DS tablet BID x 3 days OR
• Cephalexin 500mg PO QID x 5-7 days OR
• Levofloxacin 250-500mg PO QD x 3 days

Pediatric (>3 months): Amoxicillin-clavulanate 22.5/3.125 mg/kg BID or Cephalexin 25-50 mg/kg/day QID x 5-7 days

Special Considerations: avoid FQ if possible; avoid nitrofurantoin if renal impairment (CrCl <30); nitrofurantoin concentrates in urine; symptoms may improve before culture results

Pyelonephritis (Acute Uncomplicated)

Pathogens: Same as cystitis

Empiric therapy:

• Outpatient (able to tolerate PO): Levofloxacin 750mg PO QD OR Ceftriaxone 1g IM/IV QD (initial dose, then PO step-down) x 7 days
• Hospitalized: Ceftriaxone 1g IV Q12H OR Cefotaxime 1-2g IV Q8H OR Levofloxacin 750mg IV QD
• Pediatric: Ceftriaxone 50-100 mg/kg/day Q12H IV/IM OR Amoxicillin-clavulanate 22.5/3.125 mg/kg Q8H (oral, if mild)

Imaging: Renal ultrasound if obstructive symptoms, concern for abscess, immunocompromised, or recurrent pyelonephritis

Duration: 7 days

Catheter-Associated UTI (CAUTI)

Pathogens: Polymicrobial (Enterobacteriaceae, Pseudomonas, enterococci, Candida), biofilm formation

Treatment: Remove catheter if possible; treat only if symptomatic (asymptomatic bacteriuria does NOT require treatment in non-pregnant)

• Empiric: Ceftriaxone 1g IV Q12H (gram- + some Gram+) or Piperacillin-tazobactam 3.375-4.5g IV Q6H (broader)
• Duration: 5-7 days after catheter removal

---

SKIN AND SOFT TISSUE INFECTIONS

Cellulitis (Non-Purulent)

Pathogens: Group A Streptococcus (GAS), S. aureus (including MRSA in some regions)

Empiric therapy:

• Non-MRSA endemic area: Cephalexin 500mg-1g PO QID OR Amoxicillin-clavulanate 875/125mg BID OR Ceftriaxone 1g IV Q12H (if systemic toxicity)
• MRSA-endemic or risk factors: Trimethoprim-sulfamethoxazole 1-2 DS tablets BID (oral) OR Doxycycline 100mg BID (oral) OR Vancomycin 15-20 mg/kg IV Q8-12H (IV)
• Pediatric (non-MRSA): Amoxicillin-clavulanate 22.5/3.125 mg/kg BID OR Cephalexin 25-50 mg/kg/day QID
• Pediatric (MRSA): Trimethoprim-sulfamethoxazole 4-6 mg/kg (TMP) BID

Duration: 5-7 days (clinical improvement guides longer therapy)

Adjunctive: Elevation, NSAIDs for inflammation, monitor for abscess/drainage (might indicate need for incision/drainage)

Skin Abscess (Purulent)

Pathogens: S. aureus (including MRSA), streptococci

Treatment: Incision, drainage, and packing (critical); antibiotic therapy is adjunctive

• Small abscess (<5cm), immunocompetent, no systemic toxicity: I&D alone may suffice; if antibiotics given: TMP-SMX or doxycycline PO x 5-7 days
• Larger or systemic toxicity: I&D + Vancomycin 15-20 mg/kg IV Q8-12H OR Cephalexin 500mg QID (non-MRSA) x 5-10 days

Necrotizing Fasciitis

Pathogens: GAS (streptococci alone), polymicrobial (S. aureus, anaerobes, Enterobacteriaceae), Vibrio (seawater exposure), Clostridium (gas gangrene)

Clinical: Pain out of proportion to exam, systemic toxicity, rapid progression, crepitus (gas in tissues)

Emergency Management:

• Immediate surgical debridement (life-saving)
• Empiric IV antibiotics (do not delay for imaging):
  • Clindamycin 600mg IV Q6-8H (inhibits toxin production) + Penicillin G 2-4MU IV Q4-6H (GAS coverage) + Gentamicin 5-7 mg/kg IV QD (Gram- coverage)
  • Alternative: Vancomycin 15-20 mg/kg IV Q8-12H + Piperacillin-tazobactam 4.5g IV Q6H
• Pediatric: Clindamycin 13-16 mg/kg IV Q6-8H + Penicillin G 40,000 units/kg Q4-6H + Gentamicin 7.5 mg/kg Q8H

Duration: Depends on extent of debridement and clinical response; multiple debridements common; antibiotics 7-10+ days

---

GASTROINTESTINAL INFECTIONS

Clostridioides difficile Infection (CDI)

Diagnosis: GDH + toxin (2-step) or NAAT for tcdB gene on stool; colonoscopy if fulminant

Non-Severe (Cr <1.5x baseline, WBC <15):

• Vancomycin 125mg PO QID x 10 days (preferred) OR Fidaxomicin 200mg PO BID x 10 days (if recurrent)
• Metronidazole 500mg PO QID is no longer recommended (outdated due to reduced efficacy)
• Pediatric: Vancomycin 5-10 mg/kg PO QID x 10 days

Severe (Cr >1.5x baseline, WBC >15):

• Vancomycin 125mg PO QID x 10 days OR Fidaxomicin 200mg PO BID x 10 days

Fulminant (ICU, sepsis, megacolon, renal failure):

• Vancomycin 125-500mg PO QID + Metronidazole 500mg IV Q8H (metronidazole provides systemic levels)
• Surgical intervention (colectomy) if perforation, toxic megacolon

Recurrent CDI: Fidaxomicin preferred; consider fecal microbiota transplantation (FMT) if >2 recurrences

Spontaneous Bacterial Peritonitis (SBP)

Pathogens: E. coli, Klebsiella, S. pneumoniae (low opsonic activity in cirrhotic ascites)

Diagnosis: >250 neutrophils/mm³ in ascitic fluid (or >500 PMN/mm³), positive culture (only 50% positive)

Treatment:

• Ceftriaxone 1-2g IV Q12H x 7 days (covers Enterobacteriaceae, streptococci)
• Albumin supplementation (1.5 g/kg on day 1, 1 g/kg on day 3) improves outcomes
• Pediatric: Ceftriaxone 50-100 mg/kg/day Q12H

Prophylaxis (in cirrhosis with ascites):

• Norfloxacin 400mg PO QD OR Trimethoprim-sulfamethoxazole 1 DS tablet QD
• Duration: While ascites present and MELD >11 or total protein <1.5 g/dL

Acute Bacterial Peritonitis (Secondary)

Pathogens: Gram+ and Gram- (E. coli, Klebsiella, anaerobes), mixed infection

Treatment (after source control—drainage, repair of perforation):

• Ceftriaxone 1-2g IV Q12H + Metronidazole 500mg IV Q6-8H OR
• Piperacillin-tazobactam 4.5g IV Q6H (monotherapy)
• Pediatric: Ceftriaxone 50-100 mg/kg/day Q12H + Metronidazole 7.5 mg/kg Q6-8H

Duration: 3-7 days after source control completed

Viral Gastroenteritis

Pathogens: Rotavirus, Norovirus (outbreak/winter), Enteroviruses, Astrovirus, Sapovirus

Treatment: Supportive (oral/IV rehydration), no antimicrobials

• Antiemetics: Ondansetron 0.1-0.15 mg/kg IV/PO Q4-8H (pediatric)
• Antidiarrheals: Loperamide contraindicated in bloody diarrhea

---

HEPATITIS INFECTIONS

Hepatitis A

Diagnosis: Anti-HAV IgM, can test HAV RNA by PCR

Treatment: Supportive (no antiviral), fatigue/nausea management, avoid hepatotoxic substances

Prevention: HAV vaccine (2 doses, 6-18 months apart); post-exposure prophylaxis (IG or HAV vaccine if unvaccinated and exposure <14 days)

Prognosis: Self-limited; fulminant hepatic failure (<1% but mortality 0-7% if ICU)

Hepatitis B

Diagnosis: HBsAg (surface antigen), Anti-HBc (core antibody), HBe Ag/Anti-HBe (markers of replication), HBV DNA (viral load)

Acute HBV Treatment: Supportive; IFN-alpha or nucleoside analogs (tenofovir, entecavir) only if severe hepatitis or fulminant disease

Chronic HBV Treatment (if HBsAg+ >6 months):

• Tenofovir 300mg PO QD OR Entecavir 0.5mg QD (nucleos(t)ide analogs)
• Interferon alpha 5MU three times weekly or pegIFN alpha 180 µg weekly x 48 weeks (if HBe Ag+ or high viral load)
• Duration: Often lifelong; assess HBsAg loss, anti-HBs seroconversion

Pediatric (HBV treatment): Tenofovir dosing by weight, ETV 0.5 mg QD if weight >30kg

Prophylaxis: HBV vaccine series (0, 1, 6 months); post-exposure prophylaxis (HBIG + HBV vaccine if unvaccinated)

Hepatitis C

Diagnosis: Anti-HCV antibody (EIA), HCV RNA by RT-PCR, HCV genotype (1-6)

Treatment (Direct-Acting Antivirals, DAAs):

• Genotype 1-6: Sofosbuvir/ledipasvir ± ribavirin x 8-12 weeks (for most; longer for cirrhosis)
• Alternative regimens: Sofosbuvir/velpatasvir/voxilaprevir, glecaprevir/pibrentasvir
• Cure rates >95% with modern DAAs
• Pediatric: Sofosbuvir-containing regimens dosed by weight; genotype-guided

Monitoring: SVR (sustained virologic response) 12 weeks post-treatment; cirrhosis screening if advanced fibrosis

---

CENTRAL NERVOUS SYSTEM INFECTIONS

Bacterial Meningitis

Pathogens (adult): N. meningitidis, S. pneumoniae, Gram- rods (Enterobacteriaceae, Pseudomonas), Listeria (>50 or immunocompromised)

Pathogens (pediatric, >3 months): N. meningitidis, S. pneumoniae, Streptococcus agalactiae (Group B, neonates <3 months), H. influenzae (non-Hib vaccine-unvaccinated)

CSF Profile: PMN predominance, elevated protein (>100 mg/dL), low glucose (<50% serum) or <30 mg/dL, positive Gram stain/culture (50-90% sensitivity)

Empiric Therapy (before culture; do not delay):

• Adult, community-acquired: Ceftriaxone 2g IV Q12H + Vancomycin 15-20 mg/kg IV Q8-12H + Ampicillin 2g IV Q4H (Listeria coverage if >50yo, immunocompromised, or alcoholic)
• Adult, hospital-acquired/healthcare-associated: Ceftazidime 2g IV Q8H + Vancomycin 15-20 mg/kg IV Q8-12H (Pseudomonas coverage)
• Pediatric (3 months-18 years): Ceftriaxone or Cefotaxime 2g IV Q4-6H + Vancomycin 15 mg/kg IV Q6H
• Neonatal (<3 months): Ampicillin 50 mg/kg IV Q4-6H + Gentamicin 7.5 mg/kg IV Q8H + (controversial: add cefotaxime 50 mg/kg Q6H)

Adjunctive Dexamethasone: 10mg IV Q6H x 4 days (if given before/with first antibiotic dose); reduces mortality/morbidity in pneumococcal meningitis

Duration:

• N. meningitidis: 7 days
• S. pneumoniae: 10-14 days
• Gram-negative (non-Pseudomonas): 21 days
• Pseudomonas: 14-21 days
• Listeria: 14-21 days

Complications: Subdural empyema, ventriculitis, hydrocephalus, seizures; repeat LP if no CSF sterilization by 24-48h

Viral Meningitis

Pathogens: Enteroviruses (Coxsackievirus, Echovirus), Parechoviruses, Mumps (unvaccinated), HSV-2 (genital), VZV, EBV

Diagnosis: CSF enterovirus PCR (high sensitivity), lymphocytic pleocytosis, normal glucose

Treatment: Supportive (NSAIDs for headache, IV hydration); antivirals only for HSV/VZV meningitis

• HSV/VZV meningitis: Acyclovir 10-15 mg/kg IV Q8H x 10-14 days
• Mumps: Supportive only

---

BONE AND JOINT INFECTIONS

Acute Osteomyelitis

Pathogens (hematogenous, child): S. aureus, S. pyogenes, Kingella kingae

Pathogens (hematogenous, adult): S. aureus, aerobic Gram-negative rods

Pathogens (post-operative, prosthetic): Coagulase-negative Staph (biofilm), S. aureus (acute infection), Enterobacteriaceae, Pseudomonas, Propionibacterium acnes

Diagnosis: Blood cultures (often positive in acute), MRI (edema, abscess), radiographs (late findings), bone biopsy if culture-negative and diagnosis uncertain

Empiric Therapy:

• Acute hematogenous: Ceftriaxone 2g IV Q12H OR Vancomycin 15-20 mg/kg IV Q8-12H (covers Staph) + Gentamicin 5-7 mg/kg IV QD
• Pediatric: Ceftriaxone 50-100 mg/kg/day Q12H OR Cefotaxime 100-200 mg/kg/day Q4-8H
• Post-operative/prosthetic: Vancomycin 15-20 mg/kg IV Q8-12H + Gentamicin 5-7 mg/kg IV QD

Duration: Minimum 4-6 weeks IV, then consider oral fluoroquinolone or other agent (total 6-8 weeks or longer for prosthetic)

Adjunctive: Surgical debridement if purulent material/necrotic bone, imaging-guided drainage

Septic Arthritis

Pathogens: S. aureus, N. gonorrhoeae (sexually active, migratory polyarthritis), S. pyogenes, Gram-negative rods, Haemophilus spp

Diagnosis: Joint aspiration (>50,000 WBC, positive culture gold standard), blood cultures, Gram stain

Empiric Therapy:

• Gonococcal (sexually active, migratory): Ceftriaxone 1g IV Q12H or Cefotaxime 1-2g IV Q8H
• Non-gonococcal (community): Vancomycin 15-20 mg/kg IV Q8-12H OR Ceftriaxone 1-2g IV Q12H
• Pediatric: Ceftriaxone or Cefotaxime 50-100 mg/kg/day Q12H or Q8H

Duration: 2-3 weeks IV (longer for prosthetic joints, 4-6 weeks)

Adjunctive: Joint drainage/arthroscopy; daily aspiration until sterile fluid; aggressive PT

---

CARDIOVASCULAR INFECTIONS

Infective Endocarditis (IE)

Pathogens (subacute, native valve): Viridans streptococci (oral flora), Streptococcus gallolyticus (colon cancer), HACEK organisms (fastidious Gram-negative)

Pathogens (acute, native valve): S. aureus, Streptococcus agalactiae, Enterococcus, Pseudomonas (IVDU)

Pathogens (prosthetic valve, early <1 year): S. epidermidis, S. aureus, Enterococcus, Gram-negative, fungi

Diagnosis: Duke criteria (clinical, echocardiography, serology), blood cultures (2-3 sets before antibiotics), TEE (more sensitive than TTE)

Empiric Therapy (before culture/sensitivities):

• Native valve, community-acquired: Vancomycin 15-20 mg/kg IV Q8-12H + Gentamicin 3 mg/kg IV Q8H + Ceftriaxone 2g IV Q12H
• IVDU (likely S. aureus): Nafcillin 2g IV Q4H + Gentamicin 3 mg/kg IV Q8H (preferred over vancomycin if non-MRSA)
• Prosthetic valve: Vancomycin 15-20 mg/kg IV Q8-12H + Gentamicin 3 mg/kg IV Q8H + Rifampin 600mg IV/PO Q8H

Targeted Therapy (streptococcal IE, penicillin-susceptible):

• Penicillin G 2-4MU IV Q4H + Gentamicin 3 mg/kg IV Q8H x 2 weeks (streptococci only) OR
• Penicillin G 2-4MU IV Q4H x 4 weeks (monotherapy for streptococci)

Duration: 4-6 weeks (native valve), 6+ weeks (prosthetic valve)

Complications: Septic emboli, valvular regurgitation, heart block, complications requiring surgical valve replacement

---

SEXUALLY TRANSMITTED INFECTIONS (STIs)

Chlamydia trachomatis (Genital)

Presentation: Urethritis (males), cervicitis (females), often asymptomatic

Treatment:

• Azithromycin 1g PO single dose OR Doxycycline 100mg PO BID x 7 days OR Levofloxacin 500mg PO QD x 3 days
• Pediatric (uncomplicated): Azithromycin 10 mg/kg PO single dose
• Pregnancy: Azithromycin 1g PO single dose (doxycycline contraindicated)

Complications: PID, epididymitis, urethral strictures, ophthalmia neonatorum (newborn)

Neisseria gonorrhoeae

Presentation: Purulent urethritis (males), cervicitis, pharyngitis, proctitis, disseminated infection

Treatment (RESISTANT to fluoroquinolones):

• Ceftriaxone 500mg IM single dose (uncomplicated urogenital) OR Ceftriaxone 1g IM single dose
• Add azithromycin 1g PO single dose if Chlamydia not excluded
• Pediatric: Ceftriaxone 125mg IM single dose (if <45kg) or 250mg IM (if ≥45kg)

Complications: PID, tubo-ovarian abscess, bartholinitis, perihepatitis (Fitz-Hugh-Curtis)

Syphilis

Diagnosis: RPR/VDRL (nontreponemal, quantitative), FTA-ABS or TP-PA (treponemal, confirmatory), dark-field microscopy (primary/secondary)

Treatment by Stage:

• Primary/secondary/early latent (<1 year): Penicillin G benzathine 2.4MU IM single dose (gold standard)
• Late latent (>1 year) or unknown duration: Penicillin G benzathine 2.4MU IM weekly x 3 weeks
• Neurosyphilis: Penicillin G 18-24MU/day IV QID x 10-14 days
• Pediatric: Penicillin G benzathine 50,000 units/kg IM (max 2.4MU)
• Penicillin-allergic (non-pregnant): Doxycycline 100mg PO BID x 28 days (early syphilis)

Jarisch-Herxheimer Reaction: Fever, rash, transient worsening of symptoms 6-24h after first antibiotic (especially secondary syphilis); pretreat with acetaminophen/NSAIDs

---

EYE AND EAR INFECTIONS

Acute Bacterial Conjunctivitis

Pathogens: S. aureus, Streptococcus pyogenes, H. influenzae, Moraxella, Neisseria gonorrhoeae (neonates)

Treatment:

• Non-gonococcal: Topical antibiotic drops (tobramycin, ciprofloxacin, moxifloxacin) 4-6x/day x 5-7 days
• Gonococcal conjunctivitis (neonatal ophthalmia): Ceftriaxone 50mg/kg IV single dose + topical erythromycin ointment
• Systemic involvement: IV antibiotics as for generalized infection

Acute Otitis Media (AOM)

Pathogens: S. pneumoniae, H. influenzae (nontypeable), M. catarrhalis, Group A Streptococcus

Treatment:

• Amoxicillin 25-45 mg/kg/day BID-TID (pediatric) OR 500-875mg TID (adult) x 5-7 days
• If penicillin-allergic or treatment failure: Amoxicillin-clavulanate 22.5/3.125 mg/kg BID OR Cefuroxime axetil 30 mg/kg/day BID
• Fluoroquinolone drops (ofloxacin) for otitis with tympanostomy tubes

Complications: Mastoiditis (coalescent; requires imaging, drainage), meningitis

---

4. SEPSIS MANAGEMENT

Definition and Criteria

Sepsis: Life-threatening organ dysfunction caused by host response to infection; qSOFA score ≥2 predicts poor outcome

• Altered mental status (GCS <15, or delirium)
• SBP ≤100 mmHg
• Respiratory rate ≥22 breaths/min

Septic Shock: Sepsis + hypotension requiring vasopressors to maintain MAP ≥65 mmHg, lactate >2 mmol/L

Surviving Sepsis Campaign Bundles (1-Hour)

1. Measure lactate level (yes/no)
2. Blood cultures before antibiotics
3. Broad-spectrum antibiotics within 1 hour (3 hours if non-septic shock)
4. IV crystalloid fluid bolus (30 mL/kg) for hypotension or lactate ≥4
5. Vasopressor support if persistent hypotension during/after fluid resuscitation (target MAP ≥65)

Vasopressor Selection and Dosing

Norepinephrine (1st-line): 0.01-0.05 µg/kg/min, titrate to MAP ≥65 (alpha + beta effects)

Dopamine (if HR <60, cardiogenic shock risk): 5-20 µg/kg/min (at higher doses: alpha>beta, less tachycardia than epi)

Epinephrine (refractory shock, 2nd-line): 0.05-0.2 µg/kg/min (powerful alpha + beta, but arrhythmia risk)

Vasopressin: 0.04 units/min (fixed dose, often added to norepinephrine in refractory shock)

Phenylephrine: 0.5-1.4 µg/kg/min (pure alpha, no beta effects, reduces CO)

Antibiotic Empiric Therapy

Community-Acquired Sepsis:

• Ceftriaxone 1-2g IV Q12H + Vancomycin 15-20 mg/kg IV Q8-12H (dual Gram+/Gram- coverage)
• Alternative: Piperacillin-tazobactam 4.5g IV Q6H (monotherapy covers Gram+/Gram-/anaerobes)
• Add metronidazole 500mg IV Q8H if anaerobic source (intra-abdominal, aspiration)

Hospital-Acquired/Healthcare-Associated:

• Cefepime 2g IV Q8H OR Piperacillin-tazobactam 4.5g IV Q6H (Pseudomonas coverage)
• Vancomycin 15-20 mg/kg IV Q8-12H if MRSA risk or unstable

Source Control: Imaging (CXR, abdominal imaging), identify source (UTI, pneumonia, intra-abdominal, wound), drainage if loculated

Adjunctive Therapies

Hydrocortisone: 50mg IV Q6H x 7 days if refractory septic shock requiring escalating vasopressor support

Activated Protein C: No longer recommended (removed from market due to lack of benefit)

Monitoring: Lactate clearance (>10% at 6 hours indicates response), repeat lactate if elevated, urine output target 0.5 mL/kg/hr, CVP monitoring if central line placed

---

5. INFECTION CONTROL

Standard Precautions (all patients, all body fluids)

• Hand hygiene: Alcohol-based hand rub or soap/water (visible soiling requires soap/water)
• PPE: Gloves, gown, mask, eye protection based on anticipated exposure
• Respiratory hygiene: Mask for respiratory symptoms, cough etiquette
• Safe injection practices: New needle/syringe per injection, single-use medication vials
• Reusable equipment: Clean and disinfect between patients (stethoscope, blood pressure cuff)
• Environmental: Clean/disinfect high-touch surfaces daily

Transmission-Based Precautions (for specific pathogens)

Airborne (mask in room):

• Tuberculosis, measles, varicella-zoster, SARS-CoV-2 (certain variants), Mycobacterium avium complex
• Private room, negative pressure if available, N95 respirator, limit patient transport

Droplet (surgical mask):

• Influenza, pertussis, meningococcal disease, streptococcal pharyngitis, mumps, rubella, scarlet fever, parainfluenza, adenovirus, enterovirus
• Private room if available, surgical mask for healthcare workers within 6 feet

Contact (gloves + gown):

• VRE, MRSA, C. difficile, norovirus, enteroviruses, respiratory syncytial virus, scabies, herpes zoster (disseminated)
• Dedicated equipment, gloves/gown for room entry

Personal Protective Equipment (PPE)

Proper Use:

• Donning sequence: Gown → Mask/respirator → Eye protection → Gloves
• Doffing sequence (in designated area): Gloves → Gown → Eye protection → Mask/respirator → Hand hygiene
• Hand hygiene after each patient/after removing gloves
• Fit-test required for N95 respirators (annual)

Sterilization Methods

Autoclaving (steam sterilization, 121°C, 15-30 min at 15 psi): Surgical instruments, decontaminated sharps containers

High-Level Disinfection (chemical, 3-10 hours or automated): Endoscopes, semicritical items (touch mucous membranes, non-sterile body areas)

• Glutaraldehyde 2.5% (sporicidal, but slow)
• Peracetic acid (sporicidal, faster)

Low-Level Disinfection (chlorine, quaternary ammonium, phenolics, 10 min): Surfaces, equipment not in direct patient contact

• Chlorine: 0.5-5% solution (1:10 dilution of household bleach = 0.5%), effective against enveloped viruses, vegetative bacteria

Isolation Protocols

Respiratory Isolation (TB):

• Negative pressure room (≥6 air changes/hour outward)
• N95 respirator required for entry
• Duration: Until 3 consecutive negative sputum smears (1-2 weeks typically)

Contact Isolation (C. difficile, VRE, MRSA, norovirus):

• Single room if available
• Dedicated equipment (bedpan, commode, stethoscope, BP cuff)
• Hand hygiene with soap/water (alcohol ineffective against C. difficile spores)
• Gown + gloves for all patient contact

Outbreak Management

Identification: Cluster of cases exceeding baseline (epidemic curve, temporal clustering, common source)

Cohort Isolation: Group affected patients together, dedicated staff, prevent mixing with susceptible population

Environmental Investigation:

• Inspect water sources (Legionella), food sources (Salmonella), environmental surfaces
• Cultures of environment and specimens

Communication: Inform infection control team, hospital epidemiology, public health (reportable diseases), staff education

Duration: Until outbreak controlled (e.g., C. difficile outbreak: stop antibiotics if possible, strict hand washing, environmental cleaning)

---

6. PANDEMIC PREPAREDNESS

Respiratory Pandemics

Identification: Novel respiratory virus with human-to-human transmission, pandemic potential based on R0 (basic reproduction number), severity, novelty

Initial Containment:

• Case identification (syndromic surveillance)
• Isolation (home/hospital depending on severity)
• Contact tracing and quarantine (14 days post-exposure exposure)
• Personal protective equipment (PPE) conservation, rationing guidelines

Clinical Triage:

• Mild-moderate (outpatient symptomatic care): RSV/influenza-like illness, monitor for deterioration
• Severe (hospitalization): Respiratory distress, hypoxia, pneumonia, risk factors (age, comorbidities)
• Critical (ICU): ARDS, shock, multi-organ failure

Therapeutics:

• Antivirals if available (remdesivir, oseltamivir for influenza, paxlovid for COVID-19)
• Monoclonal antibodies (neutralizing antibodies, early in disease course)
• Convalescent plasma (limited evidence)
• Glucocorticoids (dexamethasone) if severe hypoxia/ARDS

Vaccine Development/Rollout:

• mRNA vaccines (if platform available, rapid development timeline)
• Traditional inactivated vaccines (slower development)
• Priority groups: Healthcare workers, elderly, immunocompromised, essential workers
• Cold chain management, vaccine hesitancy mitigation

Cholera Pandemic Preparedness

Agent: Vibrio cholerae O1/O139; epidemic potential in regions with poor sanitation, water infrastructure

Clinical: Profuse watery “rice-water” diarrhea (10+ liters/day), severe dehydration, hypovolemic shock

Treatment:

• Aggressive fluid replacement: IV Lactated Ringer or Normal Saline (match stool losses + maintenance)
• Antibiotics: Doxycycline 300mg single dose OR Ciprofloxacin 1g single dose (reduce stool output 50%)
• Zinc supplementation (children): 10-20 mg daily x 14 days (reduces subsequent infections)
• Oral rehydration solution (1L = 75 mEq Na, 65 mEq Cl, 20 mEq K, 20 mmol glucose/L)

Prevention:

• Water chlorination/treatment, sanitation infrastructure
• Oral cholera vaccine (Vaxchora): 1-3 dose regimens depending on formulation; 65-90% efficacy x 3 years

Dengue Preparedness

Agent: Dengue virus (DEN-1-4) transmitted by Aedes mosquitoes; endemic in tropical/subtropical regions

Clinical: Fever, rash, myalgias, thrombocytopenia; risk of progression to dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS)

Management:

• Supportive care: IV fluids (2-3 L/day if warning signs), platelet transfusion if <20,000 or spontaneous bleeding
• Monitor: Daily platelet count, vital signs, fluid status
• No antivirals available; NSAIDs contraindicated (bleeding risk)

Prevention:

• Vector control: Mosquito breeding site elimination, insecticide-treated bednets, environmental management
• Dengvaxia vaccine (tetravalent, live-attenuated): For seropositive individuals (prior dengue); 3 doses at 0, 6, 12 months

Ebola Preparedness

Agent: Filovirus (Zaire, Sudan, Bundibugyo); human-to-human transmission via blood/body fluids

Clinical: Fever, myalgias, rash (maculopapular), hemorrhage, coagulopathy, shock, mortality 50-90%

Management:

• Strict isolation: Negative pressure room, level 4 PPE (powered air-purifying respirator)
• Supportive care: IV fluids, blood products for coagulopathy
• Supportive monitoring: Renal function, electrolytes, coagulopathy markers
• Experimental antivirals: Monoclonal antibodies (REGN-EB3, mAbs114) reduce mortality if early

Prevention:

• Occupational exposure avoidance (healthcare worker training, PPE availability)
• Ring vaccination: rVSV-ZEBOV vaccine for contacts of confirmed cases
• Community health worker education, burial practices

Quarantine and Isolation Policies

Quarantine: Separation of exposed (asymptomatic) individuals for incubation period

• COVID-19: 5-10 days from exposure (based on transmission risk assessment)
• Measles: 21 days post-exposure (highly contagious)
• Ebola: 21 days post-exposure (incubation period)

Isolation: Separation of infected (symptomatic/confirmed) individuals for duration of contagiousness

• Respiratory viruses: Until fever-free without antipyretics x 24 hours + respiratory symptoms improving
• TB: Until 3 consecutive negative sputum smears
• C. difficile: Until diarrhea resolved

Surge Capacity Planning

Hospital Capacity:

• ICU bed surge (600-1200 ventilators per million population in pandemic)
• Staff surge (cross-train staff, mutual aid agreements with other facilities, active duty medical personnel)
• Supply chain (PPE stockpile, medications, ventilators, ECMO circuits)

Staffing Models:

• Contingency staffing (reduce hours, extend shifts)
• Crisis standards of care (rationing resources, triage protocols)
• Mental health support (burnout prevention, critical incident stress management)

Communication:

• Daily briefings (hospital leadership, staff, community)
• Transparent messaging (mortality rates, resource limitations, vaccine efficacy)
• Risk communication (behavioral recommendations, trust building)

---

7. TROPICAL AND ENDEMIC DISEASES

MALARIA

Epidemiology and Transmission

• Plasmodium parasites: P. falciparum (most severe, Africa), P. vivax (relapse, Asia), P. ovale (relapse), P. malariae (chronic), P. knowlesi (zoonotic, SE Asia)
• Anopheles mosquito transmission (dusk-dawn peak)
• Incubation: 7-30 days (P. falciparum), 8-25 days (P. vivax/ovale), 18-40 days (P. malariae)

Diagnosis

• Thick/thin blood film (gold standard, 0.5 µL blood, requires expertise)
• Rapid diagnostic test (RDT): Detects HRP-2 (P. falciparum), pLDH (pan-Plasmodium), G6PD (P. vivax/ovale)
• PCR: Most sensitive, species identification

Clinical Presentation

• Uncomplicated: Fever (cyclical, every 48h P. vivax/ovale, every 72h P. malariae), chills, myalgias, headache, hepatomegaly
• Severe: Cerebral malaria (seizures, altered mental status), severe anemia (Hb <7 g/dL), acute kidney injury, metabolic acidosis, pulmonary edema, hyperparasitemia (>5%)

Treatment by Species

P. falciparum (chloroquine-resistant):

• Artemisinin-based combination therapies (ACTs) preferred:
  • Artemether-lumefantrine (Coartem): 80/480mg BID x 3 days
  • Artesunate-amodiaquine, dihydroartemisinin-piperaquine (DHA-PPQ)
• Severe (parenteral): Artesunate 2.4 mg/kg IV at 0, 12, 24 hours, then daily (better than quinine)
• Pediatric: Artemether-lumefantrine 1.5-19kg: 1 tablet BID x 3 days (based on weight bands)
• Duration to parasite clearance: 3-7 days

P. vivax/P. ovale (with relapse):

• Acute phase: ACT (artemether-lumefantrine) OR Chloroquine 600mg, then 300mg at +6h, +24h, +48h (if sensitive regions)
• Relapse prevention: Primaquine 0.5 mg/kg daily x 14 days (must test G6PD first; hemolysis risk in G6PD deficiency)
• Pediatric: Primaquine 0.5 mg/kg daily x 14 days (test G6PD <6 months first)

P. malariae:

• Chloroquine 600mg, then 300mg +6h, +24h, +48h
• Relapse prevention: Primaquine 0.5 mg/kg daily x 14 days

Severe Malaria Management

• IV artesunate 2.4 mg/kg at 0, 12, 24 hours, then daily x 5-7 days
• Switch to oral ACT when tolerated
• Supportive: Blood transfusion if Hb <7 g/dL, seizure prophylaxis (diazepam), RBC exchange (if hyperparasitemia >10%)

Chemoprophylaxis

• Doxycycline 100mg daily x 2 days before, during, 4 weeks after (chloroquine-resistant areas)
• Mefloquine 250mg weekly x 1 week before, during, 4 weeks after (side effects: neuropsychiatric)
• Atovaquone-proguanil (Malarone): 1 tablet daily x 1 day before, during, 7 days after
• Chloroquine 300mg (base) weekly (chloroquine-sensitive areas only)

---

DENGUE FEVER

Epidemiology

• Aedes aegypti mosquito (daytime, urban)
• 4 serotypes (DEN-1-4), endemic SE Asia, Latin America
• Secondary dengue (prior different serotype) → severe dengue risk (DHF/DSS)

Clinical Phases

• Febrile phase (3-7 days): High fever, myalgia, headache, rash (maculopapular, trunk)
• Critical phase (days 3-7): Fever defervescence, rapid IV fluid loss → shock if untreated, thrombocytopenia (<100,000)
• Recovery phase: Gradual improvement, convalescent rash

Management

• Mild-moderate: Outpatient if reliable follow-up; oral rehydration, acetaminophen (avoid NSAIDs)
• Severe/DHF: IV fluids (Lactated Ringer, NS) 500-1000 mL/hr, target urine output 0.5 mL/kg/hr
• Platelet transfusion: If count <20,000 OR <50,000 with bleeding/planned procedure
• No antivirals; supportive care only

---

ENTERIC FEVER (TYPHOID/PARATYPHOID)

Agent

• Salmonella typhi (typhoid), S. paratyphi A/B (paratyphoid)
• Fecal-oral transmission, chronic carriers (bile ducts), endemic Asia/Africa

Clinical

• Week 1: Rose spots (faint pink macules on trunk), fever stepladder, relative bradycardia
• Week 2-3: Enteric fever (cough, delirium, diarrhea/constipation, hepatomegaly, splenomegaly)
• Complications: Intestinal perforation, myocarditis, meningitis, encephalitis

Diagnosis

• Blood culture (week 1, most sensitive), stool culture (week 2+), urine culture
• Widal test (O and H antibodies, less specific, endemic areas have baseline titers)
• PCR increasingly available

Treatment

Uncomplicated:

• Ceftriaxone 1-2g IV/IM Q12H x 7-14 days OR Fluoroquinolone (levofloxacin 500mg daily x 7 days, if susceptible)
• Pediatric: Ceftriaxone 50-100 mg/kg/day Q12H

Severe/Complications:

• Ceftriaxone 1-2g IV Q12H + Gentamicin 3-5 mg/kg IV Q8H
• Switch to oral agent when clinically improved

Resistance: Multi-drug resistant (MDR, chloramphenicol/ampicillin/TMP-SMX resistant) common in Asia; fluoroquinolone resistance emerging

Prevention

• Typhoid vaccine (inactivated or oral Ty21a) recommended for travelers to endemic areas
• Hygiene, safe water access, sewage sanitation

---

RABIES

Epidemiology

• Lyssavirus transmitted via saliva (bite, scratch, mucosal contact)
• Mortality ~100% once symptomatic; pre-exposure prophylaxis (PEP) highly effective

Post-Exposure Prophylaxis (PEP)

Wound Management:

1. Immediately wash with soap/water x 15 minutes
2. Apply iodine solution or 70% alcohol
3. Do NOT stitch if possible (allows drainage); if required, suture after PEP

Immunoglobulin (RIG):

• Human rabies immunoglobulin (HRIG) 20 IU/kg: Infiltrate around wound, remainder IM
• Administer within 7 days of bite

Vaccine Schedule (inactivated rabies vaccine, ICRV or PCECV):

• IM route: 1.0 mL at days 0, 3, 7, 14, 28 (5 doses)
• Intradermal route: 0.1 mL at 5-8 sites on days 0, 3, 7; 1.0 mL IM on day 28 (cost-saving)

Pediatric: Same immunoglobulin weight-based dosing; vaccine doses unchanged

Pre-Exposure Prophylaxis (PrEP)

• Indicated: Animal handlers, cave explorers (bat exposure), healthcare workers with frequent exposure
• Schedule: 1.0 mL IM on days 0, 7, 21-28
• Booster: Every 2-5 years if continued exposure risk

---

TETANUS

Epidemiology

• Clostridium tetani: soil-spore, anaerobic germination in wounds → tetanospasmin toxin (GABA inhibition → unopposed motor neuron firing)
• Risk: Puncture wounds, burns, surgical wounds, umbilical cord (developing countries)

Clinical

• Incubation: 3-21 days
• Generalized: Trismus (“lockjaw”), rigidity (opisthotonus, “risus sardonicus”), respiratory failure
• Localized: Muscle rigidity near wound; may progress to generalized
• Neonatal: Fever, poor feeding, irritability, generalized rigidity

Management

• Supportive: ICU care, mechanical ventilation (high mortality without), benzodiazepines for spasms (lorazepam, diazepam)
• Wound debridement, culture
• Antibiotics: Metronidazole 500mg IV Q6-8H x 7-10 days (or penicillin G 2-4MU IV Q4-6H)
• Tetanus immunoglobulin (TIG) 500 IU IM (for severe tetanus, early)
• Prognosis: Mortality 5-10% with supportive care (20-50% untreated)

Prevention

• Vaccination: Primary series (3 doses) + boosters every 10 years
• Wound prophylaxis (see Immunization section)

---

CHOLERA

Agent and Epidemiology

• Vibrio cholerae O1 (Classical, El Tor biotypes) and O139
• Fecal-oral transmission, water-borne, epidemic potential
• Incubation: 1-3 days

Clinical

• Rice-water diarrhea (10-20 L/day), severe dehydration, hypovolemic shock, hypoglycemia, electrolyte abnormalities
• Mortality: 1% with treatment, 50% untreated

Management

• Fluid replacement (paramount): IV Lactated Ringer (rapidly), match stool losses
  • Initial: 75 mL/kg over 4 hours (dehydrated)
  • Maintenance + ongoing losses: Monitor urine output, vitals
• Oral rehydration solution (WHO formula): 75 mEq Na, 65 mEq Cl, 20 mEq K, 20 mmol glucose/L
• Antibiotics: Doxycycline 300mg single dose (or TID x 3 days) OR Ciprofloxacin 1g single dose
  • Reduces diarrhea volume 50%, shedding duration, hospitalization
  • Pediatric: Doxycycline contraindicated; Ciprofloxacin 20-30 mg/kg/day BID x 3 days
• Supportive: Zinc (children 10-20 mg daily x 14 days), monitoring

---

LEPTOSPIROSIS

Agent and Epidemiology

• Leptospira interrogans: Soil/water contamination from infected animal urine (rodents, livestock)
• Occupational (farmers, abattoir workers, military)
• Biphasic illness

Clinical

• Leptospiremic phase (first week): Fever, myalgia, headache, conjunctival suffusion
• Immune phase (second week): IgM appears, aseptic meningitis, weil’s disease (severe: jaundice, renal failure, hemorrhage)

Diagnosis

• PCR blood/urine (first week)
• Culture (blood week 1, urine weeks 2-30, slower)
• IgM/IgG serology (week 2+)

Treatment

• Leptospiremic phase: Doxycycline 100mg BID x 7 days (if early) OR Penicillin G 2-4MU IV Q6H
• Weil’s disease (severe): Penicillin G 2-4MU IV Q4-6H x 7-10 days OR Ceftriaxone 1-2g IV Q12H
• Pediatric (<8 years, avoid doxycycline): Penicillin G 50,000 units/kg Q6H

---

8. IMMUNIZATION PROTOCOLS

VACCINE TYPES

Live Attenuated

• Mechanism: Weakened pathogen replicates in host, induces robust cellular and humoral immunity
• Examples: MMR, varicella, rotavirus, yellow fever, Ty21a (typhoid), BCG
• Precautions: Avoid in pregnancy, immunocompromised (CD4 <200); spacing (4-week minimum between live vaccines)

Inactivated/Killed

• Mechanism: Dead pathogen or component antigens; humoral response
• Examples: Polio (IPV), hepatitis A, hepatitis B, rabies, typhoid (IM), influenza (inactivated), pertussis
• No spacing requirement between different inactivated vaccines

Toxoid

• Mechanism: Inactivated bacterial toxin; antibody-mediated neutralization
• Examples: Diphtheria, tetanus toxoids
• Part of DPT/Tdap combination vaccines

Subunit/Recombinant

• Mechanism: Purified antigen (no pathogen replication risk)
• Examples: Hepatitis B (recombinant), influenza (split), pertussis acellular
• Generally well-tolerated, less immunogenic than live

Conjugate

• Mechanism: Polysaccharide antigen conjugated to carrier protein (enhances T-cell response in infants)
• Examples: PCV13 (pneumococcal), Hib, meningococcal conjugate
• Addresses poor response of infants to naked polysaccharides

mRNA Vaccines (emerging, platform)

• Mechanism: mRNA encodes viral protein (spike protein); host cells produce antigen
• Examples: COVID-19 (Pfizer/Moderna), RSV vaccine development
• Rapid development timeline, excellent immunogenicity

COLD CHAIN MANAGEMENT

Temperature Requirements

• Freezer storage (-20°C or colder): mRNA vaccines (Pfizer -80°C, Moderna -20°C), some live vaccines
• Refrigerator storage (2-8°C): Most inactivated vaccines, toxoids
• Room temperature: MMR, varicella, oral polio (OPV) for limited periods

Chain Maintenance

• Dedicated vaccine refrigerator (not food/medication mixture)
• Daily temperature monitoring (min/max thermometer or electronic probe)
• Generator backup or alternative power
• Transport in insulated boxes with ice packs
• Documentation of temperature excursions (may require reporting to manufacturer)

Vaccine Wastage Minimization

• Multi-dose vial use: Once opened, discard after specified interval (varies: 1-28 days)
• Refrigerator storage post-reconstitution critical (oral polio vaccine reconstituted only at point-of-use)
• Training on proper handling, reconstitution, aseptic technique

ADULT IMMUNIZATION SCHEDULE

Vaccine	Age 19-26	Age 27-49	Age 50-64	Age ≥65	Notes
Tdap/Td	1 dose Tdap (if not prior), then Td Q10y	Td Q10y if no prior Tdap	Td Q10y if no prior Tdap	1-time Tdap	Pertussis protection
Influenza (IIV/LAIV)	Annual	Annual	Annual	Annual	Age ≥65: High-dose or adjuvanted preferred
MMR	2 doses (if no evidence immunity)	2 doses (if no evidence immunity)	—	—	Contraindicated if immune
Varicella	2 doses (if no evidence immunity)	2 doses (if no evidence immunity)	—	—	Zoster vaccine (≥50yo) preferred instead of 2nd varicella
Zoster (Shingrix)	—	—	2 doses	2 doses	Recombinant, non-live, preferred over ZOSTAVAX
HPV (Gardasil 9)	3 doses (ages 19-26 if no prior)	3 doses (if not vaccinated; up to age 45 per individual decision)	—	—	Males 19-26 routinely; older if risk
Pneumococcal (PCV20 or PPSV23)	PCV20 x1 OR PPSV23, then PCV20	PCV20 x1 OR PPSV23 then PCV20	PCV20 x1 OR PPSV23 then PCV20	PCV20 x1 (if not prior pneumo)	≥65: PCV20 preferred
Meningococcal (MCV4/MenB)	MCV4 (if not prior), then Q5y if risk; MenB 2 doses	MCV4 or MenB if not prior	—	—	Asplenia, terminal complement deficiency
Hepatitis A	2 doses (if not immune)	2 doses (if not immune)	2 doses (if risk)	2 doses (if risk)	Risk: MSM, PWID, occupational
Hepatitis B	3 doses (if not immune)	3 doses (if not immune)	3 doses (if risk)	—	Risk: PWID, MSM, occupational
Haemophilus influenzae type b (Hib)	1 dose (if not prior)	1 dose (if not prior)	—	—	Asplenia, other risk factors
Japanese encephalitis	Travel to endemic areas	Travel to endemic areas	Travel to endemic areas	Travel to endemic areas	2 doses Vero-derived
Rabies	PrEP: 3 doses (days 0, 7, 21-28)	PrEP: 3 doses	PrEP: 3 doses	PrEP: 3 doses	Risk occupation/exposure
Yellow fever	Single dose (valid 30 years)	Single dose (valid 30 years)	Single dose	Single dose (if travel/risk)	Live-attenuated, booster not routinely recommended
Typhoid (parenteral)	Single dose (booster Q3y if risk)	Single dose (booster Q3y if risk)	Single dose (booster Q3y if risk)	Single dose	Travel to endemic areas

PEDIATRIC IMMUNIZATION SCHEDULE (Highlights)

Age	Vaccines
Birth	HepB dose 1
1-2 months	HepB dose 2, RV dose 1, DTaP dose 1, Hib dose 1, PCV13 dose 1, IPV dose 1
2 months	Same as 1-2 months (if not given at birth)
4 months	RV dose 2, DTaP dose 2, Hib dose 2, PCV13 dose 2, IPV dose 2
6 months	HepB dose 3, RV dose 3, DTaP dose 3, Hib dose 3, PCV13 dose 3, IPV dose 3, Influenza dose 1 (and dose 2 one month later)
12-15 months	Hib dose 4, PCV13 dose 4, IPV dose 4 (if not completed), MMR dose 1, Varicella dose 1, Hepatitis A dose 1, Influenza dose 1 (if not prior)
4-6 years	DTaP dose 5, IPV dose 4, MMR dose 2 (if not prior), Varicella dose 2 (if not prior), Influenza annual
11-12 years	Tdap dose 1 (if not prior), HPV dose 1 (series), Meningococcal (MCV4) dose 1, Influenza annual, Hepatitis B series (if not prior)
16-18 years	MCV4 dose 2, Meningococcal B (if not prior), Influenza annual

POST-EXPOSURE PROPHYLAXIS (PEP) PROTOCOLS

Rabies PEP

• Administration: ASAP (effective up to 14 days post-exposure, ideally within 7 days)
• RIG: 20 IU/kg body weight (infiltrate wound, remainder IM)
• ICRV/PCECV: 5 doses (IM: days 0, 3, 7, 14, 28; intradermal: days 0, 3, 7 with booster day 28)
• Booster: Single 1.0 mL IM dose if prior PrEP and exposed (vaccine day 0, RIG omitted)

Tetanus PEP

• Toxoid-containing vaccine: Td (tetanus-diphtheria) or Tdap (pertussis-containing); if tetanus vaccination >10 years ago
• TIG: 500 IU IM if wound is high-risk (contaminated, >6 hours old, crush/puncture) AND not fully vaccinated

Hepatitis B PEP (exposure: needle stick, mucous membrane contact)

• HBIG (Hepatitis B Immunoglobulin): 0.06 mL/kg IM within 24 hours (ideally)
• HBV vaccine: Dose 1 at 0 hours (can be given simultaneously as HBIG, different anatomical site)
• Complete vaccine series if prior series incomplete; check anti-HBs if prior vaccination

HIV Post-Exposure Prophylaxis (PEP)

• Duration: 28 days (preferably start within 2 hours of exposure)
• Regimen: Tenofovir/emtricitabine + raltegravir OR dolutegravir (recommended)
  • Tenofovir/emtricitabine (Truvada): 1 tablet daily
  • Raltegravir: 400mg BID (if available, preferred integrase inhibitor)
  • Dolutegravir: 50mg daily
• Pediatric dosing: Weight-based modifications

Meningococcal PEP (close contacts: household, daycare, direct respiratory)

• Ciprofloxacin 500mg single dose (preferred, cost-effective) OR
• Rifampin 600mg BID x 2 days OR
• Ceftriaxone 250mg IM single dose
• Administer within 24 hours of index case identification

---

APPENDIX: QUICK REFERENCE DOSING TABLE

Drug	Adult IV	Adult PO	Pediatric IV	Pediatric PO	Renal Adjustment
Ceftriaxone	1-2g Q12H	N/A	50-100 mg/kg Q12H	N/A	No adjustment
Vancomycin	15-20 mg/kg Q8-12H	N/A	10-15 mg/kg Q6-8H	N/A	Severe adjustment required
Levofloxacin	750mg QD	750mg QD	10-20 mg/kg QD	10-20 mg/kg QD	Adjust if CrCl <50
Metronidazole	500mg Q6-8H	500mg QID	7.5 mg/kg Q6-8H	7.5 mg/kg QID	Minor adjustment
Azithromycin	500mg QD	500mg day 1, 250 QD	10 mg/kg day 1, 5 mg/kg QD	Same	No adjustment
Doxycycline	100mg BID	100mg BID	>8yo: 2.2 mg/kg BID	>8yo: 2.2 mg/kg BID	No adjustment
TMP-SMX	5 mg/kg (TMP) Q6-12H	1-2 DS BID	6-12 mg/kg (TMP) BID	6-12 mg/kg (TMP) BID	Adjust if CrCl <30
Oseltamivir	N/A	75mg BID x 5d	N/A	By weight: 15 mg/kg BID	Adjust if CrCl <30
Acyclovir	10-15 mg/kg Q8H	400-800mg 4-5x/day	10-20 mg/kg Q8H	<12yo: 15-20 mg/kg 4x/day	Significant adjustment needed
Gentamicin	5-7 mg/kg QD	N/A	2.5 mg/kg Q8H or 7.5 mg/kg QD	N/A	Major adjustment required; TDM essential

---

Training Note: This document provides evidence-based, current clinical guidance for small hospital/clinic practice. Dosing reflects adult standard care and pediatric dosing for common infections. Always verify local resistance patterns, formulary availability, and individual patient factors (renal/hepatic function, drug allergies, contraindications) before prescribing. Regular updating recommended as resistance patterns evolve and new agents become available.