Orris

40 antibiotics each with detail clinical sign and symptoms and according to disease ICU and OPD description contraindications pediatric and adult dose

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Based on my searches of the medical library, I have sufficient foundational knowledge from the available texts (Goodman & Gilman's, Katzung's, Jawetz Microbiology, Lippincott Pharmacology, Harriet Lane Handbook) to compile a comprehensive, authoritative reference. Let me now deliver the full detailed answer.

40 Antibiotics — Clinical Reference Guide

How to Use This Table

Each entry covers: Drug Class · Indications & Clinical Signs/Symptoms · ICU vs OPD setting · Contraindications · Adult Dose · Pediatric Dose

β-LACTAMS — PENICILLINS

1. Amoxicillin

Class: Aminopenicillin
Indications & Clinical Signs/Symptoms:
  • Otitis media: ear pain, fever, bulging tympanic membrane, hearing loss
  • Sinusitis: facial pain/pressure, purulent nasal discharge, headache
  • Strep pharyngitis: sore throat, exudate, fever, lymphadenopathy
  • Community-acquired pneumonia (mild): cough, fever, lobar consolidation
  • UTI (uncomplicated): dysuria, frequency, urgency, suprapubic pain
  • H. pylori eradication (triple therapy component)
Setting: OPD — mild-to-moderate infections only
Contraindications: Penicillin/amoxicillin allergy; infectious mononucleosis (causes rash); severe renal impairment requires dose reduction
Adult Dose:
  • Standard: 500 mg PO TID or 875 mg PO BID × 7–10 days
  • H. pylori: 1 g BID × 14 days (with clarithromycin + PPI)
  • Pneumonia: 1 g TID
Pediatric Dose:
  • Standard: 40–45 mg/kg/day PO divided TID (max 500 mg/dose)
  • Otitis media (high-dose): 80–90 mg/kg/day divided BID
  • Neonates: 30 mg/kg/day divided q12h

2. Amoxicillin-Clavulanate (Co-Amoxiclav)

Class: Aminopenicillin + β-lactamase inhibitor
Indications & Clinical Signs/Symptoms:
  • Acute bacterial sinusitis: purulent nasal discharge >10 days, facial tenderness, fever
  • Animal/human bites: wound erythema, swelling, warmth, discharge
  • Complicated UTI: fever, flank pain, pyuria, bacteriuria
  • Community-acquired pneumonia: fever, productive cough, dyspnea
  • Skin/soft tissue infections: cellulitis, abscess, wound infections
  • Diabetic foot infections (mild-moderate): erythema, warmth, exudate
Setting: OPD (standard); ICU (IV form for moderate-severe infections)
Contraindications: Penicillin allergy; history of amoxicillin-clavulanate–associated cholestatic jaundice/hepatic dysfunction; severe renal failure (adjust dose)
Adult Dose:
  • PO: 875/125 mg BID or 500/125 mg TID × 7–14 days
  • IV: 1.2 g (amoxicillin 1 g/clavulanate 200 mg) q8h
Pediatric Dose:
  • PO: 40 mg/kg/day amoxicillin component divided TID (max 875 mg/dose)
  • Severe: 90 mg/kg/day divided BID (high-dose ES formulation)

3. Ampicillin

Class: Aminopenicillin
Indications & Clinical Signs/Symptoms:
  • Bacterial meningitis: fever, neck stiffness, photophobia, altered consciousness (especially Listeria in neonates/elderly/immunocompromised)
  • Enterococcal endocarditis: fever, new murmur, embolic phenomena, splenomegaly
  • Listeria meningitis/bacteremia: headache, fever, CSF pleocytosis
  • UTI/pyelonephritis
Setting: ICU (IV — meningitis, endocarditis, sepsis); OPD (PO — limited use due to resistance)
Contraindications: Penicillin allergy; ampicillin rash in EBV mononucleosis; renal dose adjustment needed
Adult Dose:
  • IV: 1–2 g q4–6h (meningitis: 2 g q4h; endocarditis: 2 g q4h × 4–6 weeks)
  • PO: 250–500 mg QID (limited use)
Pediatric Dose:
  • Neonatal meningitis: 100–200 mg/kg/day IV divided q6h
  • Meningitis (child): 200–400 mg/kg/day IV divided q4–6h (max 12 g/day)
  • Sepsis: 100–200 mg/kg/day IV divided q6h

4. Piperacillin-Tazobactam (Pip-Tazo)

Class: Antipseudomonal penicillin + β-lactamase inhibitor
Indications & Clinical Signs/Symptoms:
  • Nosocomial pneumonia: fever, purulent sputum, new infiltrate on CXR, hypoxia, ventilator-associated (VAP)
  • Intra-abdominal infections: peritonitis, abscess, fever, rebound tenderness, ileus
  • Complicated skin/soft tissue: necrotizing fasciitis — severe pain, skin discoloration, crepitus, rapid progression, fever, hypotension
  • Febrile neutropenia: fever >38.3°C, ANC <500 cells/μL, no obvious source
  • Polymicrobial sepsis: hemodynamic instability, multi-organ signs
Setting: ICU (primary); stepdown to OPD only for completing courses
Contraindications: Penicillin allergy (cross-reactivity ~1–10%); neurotoxicity risk with renal failure; avoid combination with methotrexate
Adult Dose:
  • Standard: 3.375 g IV q6h or 4.5 g IV q8h
  • Pseudomonal infections: 4.5 g IV q6h (extended infusion 3–4h preferred)
  • Febrile neutropenia: 4.5 g IV q6h
Pediatric Dose:
  • 200–400 mg/kg/day (piperacillin component) IV divided q6–8h
  • Neonates: 150 mg/kg/day divided q8h (≥36 weeks GA)

β-LACTAMS — CEPHALOSPORINS

5. Cefalexin (Cephalexin) — 1st Gen

Class: First-generation cephalosporin
Indications & Clinical Signs/Symptoms:
  • Cellulitis (non-purulent): erythema, warmth, edema, tenderness, spreading borders
  • Impetigo: honey-crusted sores, erythematous base, superficial erosions
  • Surgical prophylaxis (skin flora)
  • UTI (uncomplicated): dysuria, frequency, urgency, hematuria
Setting: OPD
Contraindications: Cephalosporin or penicillin allergy (cross-reactivity <1–2%); use caution in severe penicillin allergy
Adult Dose: 500 mg PO QID or 1 g PO BID × 7–14 days (cellulitis); UTI: 500 mg BID × 3–7 days
Pediatric Dose: 25–100 mg/kg/day PO divided QID (max 4 g/day); skin infections: 25–50 mg/kg/day divided QID

6. Cefazolin — 1st Gen (IV)

Class: First-generation cephalosporin (IV)
Indications & Clinical Signs/Symptoms:
  • Surgical site prophylaxis (most common perioperative antibiotic)
  • MSSA bacteremia: fever, positive blood cultures, signs of sepsis
  • MSSA soft tissue/bone infections: osteomyelitis — bone pain, fever, local tenderness; joint swelling in septic arthritis
Setting: ICU/hospital (IV only)
Contraindications: Cephalosporin allergy; use vancomycin for MRSA; renal dose adjustment
Adult Dose:
  • Prophylaxis: 2 g IV 30–60 min pre-incision (3 g if >120 kg)
  • Treatment: 1–2 g IV q8h (severe MSSA: 2 g IV q8h)
Pediatric Dose:
  • Prophylaxis: 25–30 mg/kg IV (max 2 g)
  • Treatment: 25–100 mg/kg/day IV divided q8h (max 6 g/day)

7. Cefuroxime — 2nd Gen

Class: Second-generation cephalosporin
Indications & Clinical Signs/Symptoms:
  • Community-acquired pneumonia: fever, cough, pleuritic chest pain, consolidation
  • Sinusitis/otitis media: facial pain, purulent discharge, ear pain
  • Lyme disease (early, PO form): erythema migrans rash, arthralgia, flu-like illness
  • UTI
Setting: OPD (PO); hospital (IV for moderate pneumonia)
Contraindications: Cephalosporin allergy; use ceftriaxone for CNS Lyme (crosses BBB better); hepatic impairment (adjust)
Adult Dose:
  • PO: 250–500 mg BID × 7–14 days
  • IV: 750 mg–1.5 g q8h
Pediatric Dose:
  • PO: 15–30 mg/kg/day divided BID (max 500 mg/dose); otitis media: 30 mg/kg/day BID
  • IV: 75–150 mg/kg/day divided q8h (max 4.5 g/day)

8. Ceftriaxone — 3rd Gen

Class: Third-generation cephalosporin
Indications & Clinical Signs/Symptoms:
  • Bacterial meningitis: severe headache, neck stiffness, Kernig's/Brudzinski's signs, photophobia, altered consciousness, CSF turbidity
  • Community-acquired pneumonia (moderate-severe): high fever, productive cough, hypoxia, multilobar infiltrates
  • Gonorrhea: urethral/vaginal discharge, dysuria, pelvic pain (PID)
  • Typhoid fever: stepwise fever, rose spots, relative bradycardia, splenomegaly
  • Sepsis: hemodynamic instability, high lactate, fever/hypothermia
  • Lyme disease (disseminated): carditis, 3rd-degree heart block, neurological signs
Setting: ICU (meningitis, severe sepsis); OPD/hospital (pneumonia, gonorrhea IM dose)
Contraindications: Cephalosporin allergy; hyperbilirubinemia in neonates (displaces bilirubin from albumin — avoid in first 28 days); avoid calcium-containing IV solutions in neonates (precipitate)
Adult Dose:
  • Meningitis/severe infection: 2 g IV q12h
  • Pneumonia: 1–2 g IV/IM once daily
  • Gonorrhea: 500 mg IM single dose (or 1 g if weight >150 kg)
  • Typhoid: 2 g IV once daily × 7–14 days
Pediatric Dose:
  • Meningitis: 100 mg/kg/day IV divided q12–24h (max 4 g/day)
  • Standard infections: 50–75 mg/kg/day IV once daily (max 2 g/day)
  • Gonorrhea (children ≥45 kg): adult dose

9. Ceftazidime — 3rd Gen (Antipseudomonal)

Class: Third-generation antipseudomonal cephalosporin
Indications & Clinical Signs/Symptoms:
  • Pseudomonas aeruginosa infections: nosocomial pneumonia, purulent sputum, VAP, bacteremia, septicemia in immunocompromised
  • Febrile neutropenia: fever, absent neutrophils, no localizing signs
  • Cystic fibrosis exacerbations: increased cough, purulent sputum, decline in FEV₁, fever
  • Melioidosis (Burkholderia pseudomallei): septicemia, pneumonia
Setting: ICU (primarily)
Contraindications: Cephalosporin allergy; consider combination with aminoglycoside for serious Pseudomonas infections; reduce dose in renal impairment
Adult Dose: 1–2 g IV q8h; severe Pseudomonas: 2 g IV q8h (extended infusion preferred)
Pediatric Dose: 100–150 mg/kg/day IV divided q8h (max 6 g/day); CF: 150 mg/kg/day divided q8h

10. Cefepime — 4th Gen

Class: Fourth-generation cephalosporin
Indications & Clinical Signs/Symptoms:
  • Febrile neutropenia: as above
  • Hospital-acquired/ventilator-associated pneumonia: fever, hypoxia, new infiltrate, purulent secretions
  • Meningitis (gram-negative): fever, meningismus, altered mentation
  • Complicated UTI/pyelonephritis: flank pain, high fever, rigors, pyuria, bacteremia
Setting: ICU
Contraindications: Cephalosporin allergy; neurotoxicity risk (encephalopathy, seizures) especially with renal impairment — monitor closely and reduce dose
Adult Dose:
  • Febrile neutropenia: 2 g IV q8h
  • HAP/VAP: 1–2 g IV q8–12h
  • Meningitis: 2 g IV q8h
Pediatric Dose: 100–150 mg/kg/day IV divided q8–12h (max 6 g/day); meningitis: 150 mg/kg/day divided q8h

11. Ceftaroline — 5th Gen (anti-MRSA)

Class: Fifth-generation cephalosporin (MRSA activity)
Indications & Clinical Signs/Symptoms:
  • MRSA skin/soft tissue infections: abscess, cellulitis with systemic signs, purulent discharge, failure of β-lactams
  • Community-acquired pneumonia: fever, productive cough, consolidation, hypoxia (when MRSA suspected)
Setting: Hospital/ICU stepdown
Contraindications: Cephalosporin allergy; renal dose adjustment (CrCl <50 mL/min); false-positive Coombs test (hemolytic anemia risk with prolonged use)
Adult Dose: 600 mg IV q12h × 5–14 days
Pediatric Dose:
  • 2 months–<2 years: 8 mg/kg IV q8h
  • 2–<18 years (<33 kg): 12 mg/kg IV q8h; (≥33 kg): 400 mg IV q8h or adult dose

β-LACTAMS — CARBAPENEMS

12. Meropenem

Class: Carbapenem
Indications & Clinical Signs/Symptoms:
  • Severe intra-abdominal sepsis: peritonitis, perforated viscus, hepatic abscess, multi-organ dysfunction
  • MDR gram-negative bacteremia: high fever, hypotension, positive cultures resistant to standard agents
  • Bacterial meningitis (gram-negative/resistant organisms): meningismus, altered consciousness, CSF gram-negative rods
  • VAP: persistent fever, purulent secretions on ventilator, new infiltrate
  • Febrile neutropenia (high-risk): severe mucositis, suspected gram-negative infection
Setting: ICU
Contraindications: Carbapenem allergy; avoid in known NDM/KPC carbapenemase-producing organisms without susceptibility; reduces valproate levels by >90% — critical interaction; seizure risk in CNS disease (lower threshold than imipenem)
Adult Dose:
  • Standard: 500 mg–1 g IV q8h
  • Meningitis/severe MDR: 2 g IV q8h (extended infusion 3–4h for PK/PD optimization)
Pediatric Dose:
  • 60 mg/kg/day IV divided q8h (standard); meningitis: 120 mg/kg/day divided q8h (max 6 g/day)
  • Neonates: 20–40 mg/kg q8–12h

13. Imipenem-Cilastatin

Class: Carbapenem + dehydropeptidase inhibitor
Indications & Clinical Signs/Symptoms:
  • Polymicrobial severe infections: intra-abdominal, pelvic, mixed aerobic/anaerobic
  • MDR gram-negative organisms (when meropenem-susceptible)
  • Acinetobacter infections: VAP, wound infections in ICU/burn units
Setting: ICU
Contraindications: Penicillin/carbapenem allergy (cross-reactivity ~1%); do NOT use for CNS infections (high seizure risk — use meropenem instead); lowers seizure threshold; reduce dose in renal impairment; valproate interaction (levels drop significantly)
Adult Dose: 500 mg–1 g IV q6–8h (max 4 g/day)
Pediatric Dose: 60–100 mg/kg/day IV divided q6h (max 4 g/day); NOT for pediatric meningitis

14. Ertapenem

Class: Carbapenem (once-daily, no Pseudomonas activity)
Indications & Clinical Signs/Symptoms:
  • Community-acquired intra-abdominal infections: appendicitis, diverticulitis, fever, peritoneal signs
  • Complicated UTI/pyelonephritis
  • Complicated skin/soft tissue infections: deep wound infections, diabetic foot
  • ESBL-producing organism infections (outpatient continuation)
Setting: Hospital → OPD (once-daily IM dosing allows outpatient completion)
Contraindications: Carbapenem allergy; not effective against Pseudomonas, Acinetobacter, or Enterococcus; valproate interaction; IM form contains lidocaine — avoid in lidocaine allergy
Adult Dose: 1 g IV/IM once daily × 5–14 days
Pediatric Dose: 15 mg/kg IV/IM q12h (max 1 g/day) for children 3 months–12 years; ≥13 years: adult dose

GLYCOPEPTIDES

15. Vancomycin

Class: Glycopeptide
Indications & Clinical Signs/Symptoms:
  • MRSA bacteremia/endocarditis: persistent fever, positive blood cultures for MRSA, new cardiac murmur, embolic lesions
  • MRSA pneumonia: severe necrotizing pneumonia, hemoptysis, cavitation on CXR, septic shock
  • MRSA meningitis/CNS infections: meningismus, altered consciousness, MRSA on CSF culture
  • Clostridioides difficile colitis (PO route): profuse watery diarrhea, cramping, fever, leukocytosis (WBC >15,000), elevated lactate — severe/complicated disease
  • Febrile neutropenia (if gram-positive source suspected)
Setting: ICU (IV for systemic MRSA); OPD (PO for C. diff)
Contraindications: Vancomycin allergy; "Red Man Syndrome" (not true allergy — infusion-rate-related histamine release; slow infusion prevents); nephrotoxicity risk — avoid concurrent nephrotoxins; ototoxicity — avoid with loop diuretics/aminoglycosides; renal dose adjustment mandatory (target AUC/MIC 400–600)
Adult Dose:
  • IV: 15–20 mg/kg q8–12h (loading dose 25–30 mg/kg in severe infections); target AUC 400–600 mg·h/L
  • PO (C. diff): 125 mg QID × 10 days (severe); 500 mg QID (severe complicated)
Pediatric Dose:
  • IV: 40–60 mg/kg/day divided q6h (adjust with TDM); neonates: 10–15 mg/kg q6–24h based on gestational age/renal function
  • PO (C. diff): 40 mg/kg/day divided QID (max 500 mg/dose)

16. Teicoplanin

Class: Glycopeptide
Indications & Clinical Signs/Symptoms:
  • MRSA infections (alternative to vancomycin): bacteremia, endocarditis, bone/joint infections — fever, bacteremia, joint effusion
  • Gram-positive skin/soft tissue infections
Setting: Hospital/ICU; can use IM or once-daily IV (advantage over vancomycin)
Contraindications: Glycopeptide allergy (cross-reactivity with vancomycin ~15%); renal dose adjustment; thrombocytopenia risk; ototoxicity
Adult Dose: Loading: 400–800 mg IV/IM q12h × 3 doses; Maintenance: 400–800 mg once daily
Pediatric Dose: Loading: 10 mg/kg q12h × 3 doses IV; Maintenance: 10 mg/kg once daily (neonates: 8 mg/kg every 48h)

AMINOGLYCOSIDES

17. Gentamicin

Class: Aminoglycoside
Indications & Clinical Signs/Symptoms:
  • Gram-negative sepsis (synergy with β-lactams): E. coli, Pseudomonas, Klebsiella bacteremia — fever, tachycardia, hypotension
  • Enterococcal endocarditis (synergy with ampicillin): fever, murmur, embolic events
  • Plague (Yersinia pestis): high fever, painful lymphadenopathy (bubo), septicemia, pneumonia
  • Pyelonephritis (Gram-negative): flank pain, high fever, rigors, pyuria
Setting: ICU; OPD (single-dose IM for pelvic infections/gonorrhea)
Contraindications: Aminoglycoside allergy; renal impairment (use with great caution — nephrotoxic); avoid concurrent nephrotoxins; ototoxicity (vestibular + cochlear) — irreversible; myasthenia gravis (neuromuscular blockade); pregnancy (ototoxicity to fetus)
Adult Dose:
  • Once-daily (preferred): 5–7 mg/kg IV q24h (monitor 6–14h post-dose level)
  • Traditional: 1–1.7 mg/kg IV q8h with TDM (trough <2 mg/L, peak 5–10 mg/L)
  • Synergy for endocarditis: 1 mg/kg IV q8h
Pediatric Dose:
  • Neonates (0–7 days, <30 weeks): 3.5 mg/kg IV q48h
  • Neonates (0–7 days, ≥35 weeks): 4 mg/kg IV q36h
  • Children: 7.5 mg/kg/day IV divided q8h OR 5–7.5 mg/kg IV q24h
  • Synergy: 2–2.5 mg/kg IV q8h

18. Amikacin

Class: Aminoglycoside (broader resistance profile)
Indications & Clinical Signs/Symptoms:
  • MDR gram-negative infections resistant to gentamicin/tobramycin: fever, organ dysfunction, positive cultures
  • Nontuberculous mycobacteria (NTM): chronic cough, nodular infiltrates, bronchiectasis
  • MDR-TB (as part of combination regimen)
  • Pseudomonas aeruginosa in CF: progressive dyspnea, purulent sputum, declining lung function
Setting: ICU (systemic); inhaled form for NTM in OPD
Contraindications: Same as gentamicin — nephrotoxicity, ototoxicity (primarily cochlear), renal impairment, pregnancy, myasthenia gravis; lower resistance transfer compared to gentamicin/tobramycin
Adult Dose:
  • Once-daily: 15–20 mg/kg IV q24h (max 1.5 g/day)
  • MDR-TB: 15 mg/kg IM/IV 5 days/week
Pediatric Dose:
  • Neonates: 7.5 mg/kg IV q12–36h (GA-dependent)
  • Children: 15–22.5 mg/kg/day IV divided q8h (or 15 mg/kg once daily)

FLUOROQUINOLONES

19. Ciprofloxacin

Class: Fluoroquinolone (2nd gen, best gram-negative activity)
Indications & Clinical Signs/Symptoms:
  • Complicated UTI/pyelonephritis: flank pain, fever, costovertebral angle tenderness, bacteriuria
  • Inhalational anthrax (post-exposure prophylaxis/treatment): fever, mediastinal widening on CXR, dyspnea, septic shock
  • Traveler's diarrhea (Campylobacter, Salmonella, E. coli): watery/bloody diarrhea, cramps, nausea, vomiting
  • Typhoid fever: stepwise fever, rose spots, bradycardia, splenomegaly
  • Bone/joint infections (osteomyelitis): bone pain, soft tissue swelling, draining sinus
  • Prostatitis: perineal pain, dysuria, fever, tender prostate
  • Pseudomonas infections (non-CNS)
Setting: OPD (PO excellent bioavailability ≈85%); ICU (IV for anthrax, severe Pseudomonas)
Contraindications: Fluoroquinolone allergy; children/adolescents <18 years (cartilage damage in growing joints — use only when benefits outweigh risks, e.g., anthrax, CF); pregnancy/breastfeeding; tendon rupture risk (especially Achilles) — elevated in elderly, steroids, renal failure; QT prolongation — avoid with Class IA/III antiarrhythmics; lowers seizure threshold (caution in epilepsy); divalent cation interactions (antacids, iron, dairy reduce absorption — separate by 2h)
Adult Dose:
  • UTI (uncomplicated): 250 mg PO BID × 3 days
  • Complicated UTI/pyelonephritis: 500 mg PO BID × 7–14 days; or 400 mg IV q12h
  • Anthrax: 500 mg PO BID × 60 days; severe: 400 mg IV q12h
  • Bone/joint: 500–750 mg PO BID × 4–8 weeks
Pediatric Dose:
  • Generally avoided in children <18 years
  • Anthrax/CF/specific indications: 15 mg/kg PO q12h (max 500 mg/dose); 10 mg/kg IV q12h (max 400 mg/dose)
  • Inhalational anthrax: 10–15 mg/kg PO BID × 60 days

20. Levofloxacin

Class: Fluoroquinolone (3rd gen, respiratory)
Indications & Clinical Signs/Symptoms:
  • Community-acquired pneumonia: fever, productive cough, consolidation, hypoxia (atypicals: Legionella — high fever, hyponatremia, diarrhea, confusion; Mycoplasma — dry cough, pharyngitis)
  • Exacerbation of chronic bronchitis/COPD: increased dyspnea, purulent sputum, change in sputum color
  • Sinusitis (second-line): facial pressure, purulent nasal discharge
  • UTI/pyelonephritis
  • Tuberculosis (second-line, fluoroquinolone-sensitive MDR-TB)
Setting: OPD (excellent PO bioavailability); ICU (IV when severe pneumonia, Legionella)
Contraindications: Same class warnings as ciprofloxacin — QT prolongation, tendon rupture, seizures, avoid in children <18 (except specific indications), pregnancy; peripheral neuropathy (may be irreversible); dysglycemia (both hypoglycemia and hyperglycemia)
Adult Dose:
  • CAP: 750 mg PO/IV once daily × 5 days (or 500 mg once daily × 7–14 days)
  • Pyelonephritis: 750 mg PO once daily × 5 days
  • MDR-TB: 750–1000 mg once daily
Pediatric Dose:
  • Not routinely recommended in children <18 years
  • Specific indications (plague, anthrax): 8 mg/kg q12h PO/IV (max 250 mg/dose); ≥50 kg: 500 mg once daily

21. Moxifloxacin

Class: Fluoroquinolone (4th gen, anaerobic + atypical coverage)
Indications & Clinical Signs/Symptoms:
  • Community-acquired pneumonia (atypical): fever, dry cough, extrapulmonary findings (Legionella: hyponatremia, diarrhea; Mycoplasma: cold agglutinins, hemolytic anemia)
  • Intra-abdominal infections (anaerobic coverage)
  • Tuberculosis (MDR-TB regimen)
  • Sinusitis/exacerbated COPD
Setting: OPD/hospital (NOTE: no IV available in all markets; no urinary excretion — NOT for UTI)
Contraindications: Same fluoroquinolone class warnings; avoid in UTI (inadequate urinary levels); greater QT prolongation risk than other fluoroquinolones — strict contraindication with other QT-prolonging drugs; caution in cardiac disease; avoid in hepatic failure (Child-Pugh C); not recommended <18 years
Adult Dose: 400 mg PO/IV once daily × 5–10 days
Pediatric Dose: Not approved; use only if no alternatives (MDR-TB, specific indications): 7.5–10 mg/kg once daily

MACROLIDES

22. Azithromycin

Class: Macrolide (azalide)
Indications & Clinical Signs/Symptoms:
  • Community-acquired pneumonia (atypicals): dry/non-productive cough, gradual onset, low-grade fever, myalgia, interstitial pattern on CXR
  • Chlamydia trachomatis: urethral discharge, dysuria, cervicitis, or asymptomatic
  • Pertussis (whooping cough): paroxysmal cough, inspiratory whoop, post-tussive vomiting, cyanosis in infants
  • MAC prophylaxis/treatment in HIV: chronic cough, fever, night sweats, weight loss, lymphadenopathy (CD4 <50 cells/μL)
  • Traveler's diarrhea (Campylobacter — first-line in Asia due to fluoroquinolone resistance)
  • Cholera: rice-water diarrhea, severe dehydration, sunken eyes, skin tenting
Setting: OPD (primarily); ICU (IV azithromycin for severe atypical pneumonia)
Contraindications: Macrolide allergy; QT prolongation risk — avoid with other QT-prolonging agents; CYP3A4 inhibitor — interactions with warfarin, statins, digoxin, tacrolimus; avoid in hepatic dysfunction (excreted in bile); do NOT use as monotherapy for severe CAP (needs β-lactam combination)
Adult Dose:
  • Z-pack (CAP): 500 mg PO day 1, then 250 mg once daily × 4 more days
  • Chlamydia: 1 g PO single dose
  • Pertussis: 500 mg PO day 1, then 250 mg once daily × 4 days
  • MAC prophylaxis (HIV): 1.2 g PO once weekly
Pediatric Dose:
  • CAP: 10 mg/kg PO day 1 (max 500 mg), then 5 mg/kg/day × 4 days (max 250 mg/day)
  • Pertussis: same as CAP regimen; infants <1 month: 10 mg/kg once daily × 5 days
  • Chlamydia (≥45 kg): adult dose; (<45 kg): 20 mg/kg single dose (max 1 g)

23. Clarithromycin

Class: Macrolide
Indications & Clinical Signs/Symptoms:
  • H. pylori eradication: epigastric pain, dyspepsia, peptic ulcer, positive urea breath test
  • CAP (atypicals)
  • MAC treatment (HIV/immunocompromised): disseminated infection, fever, weight loss, bacteremia
  • Pertussis (alternative)
  • Skin/soft tissue infections
Setting: OPD
Contraindications: Macrolide allergy; QT prolongation; significant CYP3A4 inhibitor — interacts with statins (myopathy risk), warfarin (elevated INR), tacrolimus, cyclosporine, colchicine, some antiretrovirals; avoid in hepatic failure; avoid in pregnancy (teratogenic risk in animals); reduce dose with renal impairment
Adult Dose:
  • CAP: 250–500 mg PO BID × 7–14 days
  • H. pylori: 500 mg PO BID × 14 days (with amoxicillin + PPI)
  • MAC: 500 mg PO BID (combination)
Pediatric Dose: 15 mg/kg/day PO divided BID (max 500 mg/dose); H. pylori: 15 mg/kg/day BID × 14 days

24. Erythromycin

Class: Macrolide (original)
Indications & Clinical Signs/Symptoms:
  • Legionnaires' disease: high fever, myalgia, hyponatremia, confusion, bilateral pneumonia, diarrhea
  • Campylobacter enteritis: watery/bloody diarrhea, abdominal cramps, fever
  • Diphtheria: pseudomembrane on pharynx/tonsils, bull-neck appearance, myocarditis, nerve palsies
  • Gastroparesis (prokinetic use): nausea, vomiting, early satiety, abdominal fullness
  • Pertussis carrier eradication
Setting: OPD (largely replaced by azithromycin/clarithromycin due to side effects)
Contraindications: Macrolide allergy; significant GI intolerance (nausea, vomiting, diarrhea — very common); strong QT prolongation risk; CYP3A4 inhibitor; hypertrophic pyloric stenosis in neonates (<6 weeks of age — azithromycin preferred); hepatotoxicity (cholestatic jaundice with estolate salt)
Adult Dose: 250–500 mg PO QID or 500 mg–1 g IV q6h; gastroparesis: 250 mg PO TID before meals
Pediatric Dose: 30–50 mg/kg/day PO divided QID (max 2 g/day); neonates >1 month: 40 mg/kg/day divided q6h; avoid in neonates <1 month (pyloric stenosis risk)

TETRACYCLINES

25. Doxycycline

Class: Tetracycline (2nd gen)
Indications & Clinical Signs/Symptoms:
  • Chlamydia trachomatis: urethral/vaginal discharge, dysuria, pelvic inflammatory disease (PID) — lower abdominal pain, adnexal tenderness, fever
  • Lyme disease (early and late, except CNS): erythema migrans, arthralgia, facial palsy
  • Rocky Mountain Spotted Fever (RMSF): fever, rash starting on wrists/ankles spreading centrally, headache, photophobia — drug of choice at all ages including children
  • Malaria prophylaxis and treatment (combination): fever, chills, rigors, splenomegaly
  • Atypical pneumonia (Mycoplasma, Chlamydophila)
  • Brucellosis: undulant fever, arthralgia, hepatosplenomegaly, orchitis
  • Q fever (Coxiella burnetii): fever, hepatitis, pneumonia
  • Cholera (adjunct to rehydration): profuse rice-water diarrhea, severe dehydration
  • Anthrax (alternative to ciprofloxacin): bioterrorism scenario
Setting: OPD (primarily); ICU (IV for severe RMSF, inhalational anthrax)
Contraindications: Tetracycline allergy; children <8 years (dental staining, enamel hypoplasia, bone growth effects) — EXCEPT for RMSF where benefit outweighs risk; pregnancy (teratogenic — fetal bone/tooth effects, hepatotoxicity); breastfeeding; avoid with antacids, dairy, iron (chelation reduces absorption — separate by 2–3h); avoid in severe hepatic impairment
Adult Dose:
  • STI/PID: 100 mg PO BID × 7–14 days
  • Lyme: 100 mg PO BID × 14–21 days (early); × 28 days (Lyme arthritis)
  • RMSF: 100 mg PO/IV BID × minimum 3 days after fever resolves (typically 7–10 days)
  • Malaria prophylaxis: 100 mg PO once daily starting 1–2 days before travel
Pediatric Dose:
  • <8 years: generally contraindicated — EXCEPT RMSF (use 2.2 mg/kg PO/IV q12h, max 100 mg/dose)
  • ≥8 years: 2.2 mg/kg PO q12h (max 100 mg/dose × 2)
  • RMSF all ages: 2.2 mg/kg q12h IV/PO (max 100 mg/dose); complete 3 days after fever defervescence

26. Minocycline

Class: Tetracycline (2nd gen)
Indications & Clinical Signs/Symptoms:
  • Acne vulgaris: inflammatory papules, pustules, nodules (moderate-severe)
  • MRSA skin infections (oral option): cellulitis, furunculosis
  • Nocardiosis: pulmonary nodules, cavitation, skin/CNS abscesses in immunocompromised
  • Acinetobacter baumannii infections (MDR salvage)
  • Gonorrhea (alternative)
Setting: OPD (acne, MRSA skin); ICU (Acinetobacter salvage)
Contraindications: Same as doxycycline; vestibular side effects (dizziness, vertigo, tinnitus) — unique to minocycline; autoimmune lupus-like syndrome and hepatitis with long-term use; SJS/TEN (rare); drug-induced hyperpigmentation
Adult Dose: 100 mg PO BID (loading: 200 mg); acne: 50–100 mg PO BID
Pediatric Dose: Avoid <8 years; ≥8 years: 4 mg/kg PO (loading), then 2 mg/kg q12h (max 100 mg/dose)

SULFONAMIDES & FOLATE ANTAGONISTS

27. Trimethoprim-Sulfamethoxazole (TMP-SMX / Co-trimoxazole)

Class: Sulfonamide + dihydrofolate reductase inhibitor
Indications & Clinical Signs/Symptoms:
  • Uncomplicated UTI: dysuria, frequency, urgency — first-line where resistance <20%
  • Pneumocystis jirovecii pneumonia (PCP): gradually worsening dyspnea on exertion, dry cough, hypoxia, bilateral ground-glass infiltrates, elevated LDH — in HIV (CD4 <200), transplant recipients, immunocompromised
  • Toxoplasma gondii (CNS): ring-enhancing brain lesions on MRI, focal neurological deficits, seizures, headache (AIDS patient)
  • Nocardiosis: pulmonary/CNS abscesses in immunocompromised
  • MRSA skin/soft tissue infections: abscess, furunculosis, purulent cellulitis
  • Stenotrophomonas maltophilia (MDR organism): drug of choice; pneumonia/bacteremia in immunocompromised
  • Traveler's diarrhea (enteric pathogens)
Setting: OPD (UTI, PCP prophylaxis, MRSA skin, chronic therapy); ICU (high-dose IV for severe PCP)
Contraindications: Sulfonamide allergy (rash, Stevens-Johnson syndrome — SJS); G6PD deficiency (hemolytic anemia); pregnancy (third trimester — kernicterus); neonates <6–8 weeks (displaces bilirubin); renal impairment (adjust dose or avoid); hyperkalemia risk (high doses block tubular potassium secretion); interactions with warfarin (↑ INR), ACE inhibitors/ARBs, methotrexate; folate deficiency
Adult Dose:
  • UTI: 1 DS tab (160/800 mg) PO BID × 3 days
  • PCP treatment: 15–20 mg/kg/day TMP component IV/PO divided q6–8h × 21 days
  • PCP prophylaxis: 1 DS tab PO once daily (or TID 3 days/week)
  • MRSA skin: 1–2 DS tabs PO BID × 7–14 days
Pediatric Dose:
  • UTI: 8–10 mg/kg/day TMP component PO divided BID × 3–10 days
  • PCP treatment: 15–20 mg/kg/day TMP component IV/PO divided q6–8h × 21 days
  • PCP prophylaxis: 150 mg/m²/day TMP component PO divided BID for 3 consecutive days/week
  • Contraindicated <6 weeks of age

NITROIMIDAZOLES

28. Metronidazole

Class: Nitroimidazole
Indications & Clinical Signs/Symptoms:
  • Clostridioides difficile (mild-moderate, or when vancomycin unavailable): watery diarrhea, cramping, low-grade fever, leukocytosis
  • Bacterial vaginosis: thin gray/white vaginal discharge, fishy odor (positive whiff test), clue cells on microscopy
  • Trichomonas vaginalis: frothy yellow-green vaginal discharge, vulvar pruritus, strawberry cervix
  • Amoebic dysentery/liver abscess: bloody diarrhea, right upper quadrant pain, tender hepatomegaly, fever
  • Anaerobic infections: brain abscess, aspiration pneumonia, intra-abdominal abscess, necrotizing fasciitis (anaerobic component)
  • Giardiasis: malodorous fatty diarrhea, bloating, cramping, no blood in stool
  • H. pylori (component of triple therapy)
Setting: OPD (BV, trichomoniasis, Giardia); ICU (IV for anaerobic infections, brain abscess, severe amoebic disease)
Contraindications: Nitroimidazole allergy; alcohol interaction (disulfiram-like reaction — severe nausea/vomiting, flushing, tachycardia) — avoid alcohol during and 48h after treatment; peripheral neuropathy and CNS toxicity with prolonged/high doses; carcinogenic potential (animal studies) — use shortest effective course; warfarin interaction (↑ INR); avoid in first trimester of pregnancy (teratogenic risk — use in 2nd/3rd trimester if benefit outweighs risk)
Adult Dose:
  • BV/Trichomonas: 500 mg PO BID × 7 days; or 2 g PO single dose (Trichomonas)
  • C. diff (mild-moderate): 500 mg PO TID × 10–14 days (3rd-line now per IDSA)
  • Amoebic liver abscess: 750 mg PO TID × 7–10 days + luminal agent
  • Anaerobic infections IV: 500 mg IV q8h
Pediatric Dose:
  • Giardia/amoeba: 35–50 mg/kg/day PO divided TID × 7–10 days (max 750 mg/dose)
  • BV (adolescent): 500 mg PO BID × 7 days
  • Anaerobic IV: 30 mg/kg/day IV divided q6–8h (max 4 g/day)
  • Neonates: 7.5 mg/kg IV q48h (adjust for GA)

LINCOSAMIDES

29. Clindamycin

Class: Lincosamide
Indications & Clinical Signs/Symptoms:
  • Aspiration pneumonia/anaerobic lung abscess: foul-smelling sputum, cavitation on CXR, putrid breath, subacute fever
  • MRSA skin/soft tissue infections (non-purulent cellulitis, osteomyelitis): erythema, induration, bone pain, drainage
  • Bacterial vaginosis (topical/vaginal)
  • Toxoplasmosis (combination with pyrimethamine — penicillin-allergic patients)
  • Malaria (P. falciparum — combination): febrile illness, chills, splenomegaly
  • Streptococcal toxic shock syndrome (TSS) / necrotizing fasciitis (adjunct): suppresses toxin production (Eagle effect prevention)
  • Osteomyelitis (gram-positive)
  • PCP (alternative: clindamycin + primaquine)
Setting: OPD (skin/soft tissue, MRSA, BV); ICU (IV for severe infections, TSS, aspiration pneumonia)
Contraindications: Lincosamide allergy; C. difficile risk (historically among highest-risk antibiotics for C. diff — counsel patients re: diarrhea); avoid in meningitis (poor CNS penetration); neuromuscular blockade (caution in myasthenia gravis); hepatic impairment (adjust dose)
Adult Dose:
  • PO: 300–450 mg TID-QID × 7–14 days
  • IV: 600–900 mg IV q8h (TSS/severe: 900 mg IV q8h)
  • Topical gel (acne/BV): apply BD
Pediatric Dose:
  • PO: 30–40 mg/kg/day divided TID-QID (max 1.8 g/day)
  • IV: 25–40 mg/kg/day divided q6–8h (max 4.8 g/day; TSS: 40 mg/kg/day)
  • Neonates >7 days: 15–20 mg/kg/day divided q6–8h

OXAZOLIDINONES

30. Linezolid

Class: Oxazolidinone
Indications & Clinical Signs/Symptoms:
  • MRSA pneumonia (HAP/VAP): fever, purulent secretions, new infiltrate, high WBC — when vancomycin fails or intolerable
  • VRE (Vancomycin-Resistant Enterococcus) infections: bacteremia, UTI, wound infections in ICU
  • MRSA skin/soft tissue infections: abscess, surgical wound infections, failed β-lactam therapy
  • MDR-TB (component of BPaL regimen): persistent positive sputum cultures, treatment failure
  • Nocardiosis
Setting: ICU (VAP, MRSA bacteremia if vancomycin intolerant); OPD (100% PO bioavailability — step-down option)
Contraindications: MAO inhibitor use (serotonin syndrome — severe); concurrent serotonergic drugs (SSRIs, TCAs, tramadol, meperidine, fentanyl — serotonin syndrome risk); thrombocytopenia (platelets <100K) — monitor CBC weekly; lactic acidosis and peripheral neuropathy with prolonged use (>2 weeks); optic neuritis with long-term use; tyramine-rich foods (aged cheese, cured meats, fermented products) — hypertensive crisis
Adult Dose: 600 mg PO/IV q12h × 10–28 days (MDR-TB: 600 mg once daily, may reduce to 300 mg for tolerability)
Pediatric Dose:
  • <12 years: 10 mg/kg PO/IV q8h (max 600 mg/dose)
  • ≥12 years: 600 mg PO/IV q12h
  • Neonates ≥7 days: 10 mg/kg q8h; preterm neonates <7 days: 10 mg/kg q12h

LIPOPEPTIDES

31. Daptomycin

Class: Lipopeptide
Indications & Clinical Signs/Symptoms:
  • MRSA bacteremia and right-sided endocarditis: persistent bacteremia, fever, positive blood cultures for MRSA — superior to vancomycin for bacteremia (non-inferior for right-sided endocarditis)
  • VRE bacteremia
  • MRSA skin/soft tissue infections (alternative to vancomycin)
Setting: ICU (bacteremia/endocarditis); hospital
Contraindications: Daptomycin allergy; DO NOT USE for pneumonia (inactivated by lung surfactant); eosinophilic pneumonitis (if new cough/dyspnea develops — stop drug); myopathy/rhabdomyolysis (elevated CK) — monitor weekly; discontinue if CK >1000 U/L with symptoms; concurrent statins increase myopathy risk — hold statins if possible; dose adjustment required in renal impairment (CrCl <30 mL/min: q48h)
Adult Dose:
  • Bacteremia/endocarditis: 6–10 mg/kg IV once daily (complex: up to 10–12 mg/kg)
  • Skin/soft tissue: 4 mg/kg IV once daily × 7–14 days
Pediatric Dose:
  • 1–6 years: 12 mg/kg IV once daily
  • 7–11 years: 9 mg/kg IV once daily
  • 12–17 years: 7 mg/kg IV once daily
  • ≥18 years: adult dose

POLYMYXINS

32. Colistin (Polymyxin E)

Class: Polymyxin
Indications & Clinical Signs/Symptoms:
  • Extensively drug-resistant (XDR) Acinetobacter baumannii: VAP, wound infections, bacteremia — multidrug resistance pattern, previous treatment failures
  • XDR Pseudomonas aeruginosa: VAP in ICU
  • Carbapenem-resistant Klebsiella pneumoniae: bacteremia, UTI, HAP
  • Last-resort antibiotic for MDR gram-negative infections
Setting: ICU (almost exclusively — toxicity profile limits outpatient use)
Contraindications: Known allergy; nephrotoxicity (acute kidney injury — dose-dependent) — mandatory renal function monitoring daily; neurotoxicity (paresthesias, perioral numbness, neuromuscular blockade, apnea); avoid or dose-adjust in renal impairment (paradoxically, insufficient dosing leads to resistance); use aerosolized form adjunctively for VAP without systemic toxicity; avoid concurrent nephrotoxins (aminoglycosides, vancomycin); pregnancy risk
Adult Dose:
  • Loading: 9 million IU (MIU) IV, then maintenance based on CrCl
  • Standard maintenance: 4.5 MIU IV q12h (normal renal function)
  • Inhalational (VAP adjunct): 1–2 MIU nebulized q12h
Pediatric Dose:
  • 50,000–75,000 IU/kg/day IV divided q6–8h (max 300,000 IU/kg/day)
  • Inhaled: 1 MIU nebulized q12h (CF, VAP adjunct)

RIFAMYCINS

33. Rifampicin (Rifampin)

Class: Rifamycin
Indications & Clinical Signs/Symptoms:
  • Tuberculosis (first-line, part of RIPE regimen): chronic cough, hemoptysis, night sweats, weight loss, upper lobe cavitation on CXR, positive AFB smear
  • Leprosy (multibacillary, part of MDT): skin patches with sensory loss, thickened peripheral nerves, nodules (lepromatous)
  • Meningococcal prophylaxis (post-exposure): close contacts of confirmed N. meningitidis — chemoprophylaxis
  • Staphylococcal biofilm infections (prosthetic joint/device): fever, implant pain, sinus tracts — combined with other agents (NEVER as monotherapy due to rapid resistance)
  • Brucellosis (combination)
Setting: OPD (TB, leprosy); ICU (prosthetic device infections as adjunct)
Contraindications: Rifamycin allergy; potent CYP450 inducer (CYP3A4, 1A2, 2C9, 2C19) — reduces plasma levels of: oral contraceptives (use alternative contraception), warfarin, HIV antiretrovirals, antifungals, methadone, digoxin, statins, tacrolimus, cyclosporine; hepatotoxicity — monitor LFTs; NEVER monotherapy (rapid resistance develops); orange discoloration of body fluids (urine, tears, sweat — warn patient); avoid during first trimester of pregnancy
Adult Dose:
  • TB: 10 mg/kg/day PO (max 600 mg/day) in RIPE regimen × 6 months
  • Meningococcal prophylaxis: 600 mg PO q12h × 2 days
  • Staphylococcal device infection: 300–450 mg PO BID (combination)
Pediatric Dose:
  • TB: 10–20 mg/kg/day PO once daily (max 600 mg/day)
  • Meningococcal prophylaxis: <1 month: 5 mg/kg q12h × 2 days; >1 month: 10 mg/kg q12h × 2 days (max 600 mg/dose)

NITRОФURANS

34. Nitrofurantoin

Class: Nitrofuran
Indications & Clinical Signs/Symptoms:
  • Uncomplicated lower UTI: dysuria, frequency, urgency, suprapubic pain — caused by E. coli (most common), Enterococcus, Staphylococcus saprophyticus
  • UTI prophylaxis (recurrent UTI in women): frequent recurrences, no anatomical abnormality
Setting: OPD only
Contraindications: Renal impairment (CrCl <30–45 mL/min) — accumulation causes toxicity, loss of efficacy; G6PD deficiency (hemolytic anemia); pulmonary toxicity (acute: fever, cough, dyspnea — rare; chronic: pulmonary fibrosis with long-term use); hepatotoxicity with long-term use; peripheral neuropathy (prolonged use); not for upper UTI/pyelonephritis (inadequate tissue levels); avoid at term of pregnancy (38–42 weeks — risk of hemolysis in newborn); neonates <1 month
Adult Dose:
  • Macrocrystalline: 100 mg PO BID × 5 days (or 50–100 mg QID × 7 days)
  • Prophylaxis: 50–100 mg PO at bedtime
Pediatric Dose:
  • Treatment: 5–7 mg/kg/day PO divided QID (max 400 mg/day)
  • Prophylaxis: 1–2 mg/kg/day PO at bedtime (max 100 mg/day)
  • Contraindicated in neonates <1 month and infants with G6PD deficiency

ANTI-STAPHYLOCOCCAL PENICILLINS

35. Nafcillin / Flucloxacillin (Dicloxacillin — oral)

Class: Penicillinase-resistant penicillin
Indications & Clinical Signs/Symptoms:
  • MSSA (methicillin-susceptible S. aureus) bacteremia: high fever, positive blood cultures, hemodynamic instability
  • MSSA endocarditis: fever, new murmur, embolic lesions, Roth spots, Janeway lesions, Osler's nodes, splinter hemorrhages
  • MSSA osteomyelitis: bone pain, localized tenderness, fever, elevated ESR/CRP, positive bone scan
  • MSSA septic arthritis: hot swollen joint, restricted movement, fever, purulent joint fluid
Setting: ICU (IV for bacteremia/endocarditis); OPD (flucloxacillin/dicloxacillin PO for skin/wound infections)
Contraindications: Penicillin allergy; nafcillin is hepatically eliminated (dose-adjust in severe hepatic failure — unlike most β-lactams); interstitial nephritis; nafcillin causes hypokalemia; use cefazolin or vancomycin for MRSA
Adult Dose:
  • Bacteremia/endocarditis: Nafcillin 1–2 g IV q4h × 4–6 weeks
  • Osteomyelitis: 1.5–2 g IV q4–6h
  • Flucloxacillin PO: 500 mg QID (on empty stomach)
Pediatric Dose:
  • Nafcillin IV: 150–200 mg/kg/day divided q4–6h (max 12 g/day)
  • Neonates: 25–50 mg/kg/day divided q6–12h (GA-dependent)
  • Dicloxacillin PO: 12.5–25 mg/kg/day divided QID (max 500 mg/dose)

ANTI-TB (SECOND-LINE)

36. Isoniazid (INH)

Class: Isonicotinic acid hydrazide (anti-mycobacterial)
Indications & Clinical Signs/Symptoms:
  • Active tuberculosis (first-line RIPE regimen): cough >2–3 weeks, hemoptysis, night sweats, weight loss, fever, upper lobe infiltrates/cavitation
  • Latent TB infection (LTBI): positive TST (≥5–15 mm depending on risk group) or positive IGRA, no symptoms, normal CXR — chemoprophylaxis to prevent reactivation
  • TB meningitis (penetrates CNS well): meningismus, altered consciousness, high-protein/low-glucose CSF, basilar meningeal enhancement on MRI
Setting: OPD (LTBI, active TB continuation phase); ICU (initial intensive phase with other agents for severe TB, meningitis)
Contraindications: Active hepatic disease; previous INH-associated hepatic injury; peripheral neuropathy (B6 deficiency — prescribe pyridoxine 25–50 mg/day concurrently, especially in diabetics, malnourished, HIV+, elderly, pregnancy); hepatotoxicity (asymptomatic transaminase elevation common; stop if ALT >3–5× ULN with symptoms); drug-induced lupus; seizures (pyridoxine-depleting effect); CYP2E1 inhibitor; slow vs. fast acetylators (pharmacogenomics)
Adult Dose:
  • Active TB: 5 mg/kg/day PO (max 300 mg/day) × 6 months (RIPE)
  • LTBI: 300 mg PO once daily × 9 months (or 900 mg twice weekly × 9 months DOT); or INH+rifapentine once weekly × 3 months (3HP)
Pediatric Dose:
  • Active TB: 10–15 mg/kg/day PO (max 300 mg/day)
  • LTBI: 10 mg/kg/day PO (max 300 mg/day) × 9 months
  • TB meningitis: 10–15 mg/kg/day × 12 months (with other agents)
  • Always give pyridoxine 1–2 mg/kg/day alongside

ANTIFUNGAL (ANTIBACTERIAL CONTEXT — POLYENE)

37. Aztreonam

Class: Monobactam
Indications & Clinical Signs/Symptoms:
  • Gram-negative aerobic infections in penicillin/cephalosporin-allergic patients (no cross-reactivity with aztreonam): UTI, pyelonephritis, bacteremia, pneumonia caused by E. coli, Klebsiella, Pseudomonas aeruginosa
  • Febrile neutropenia (alternative in β-lactam allergy)
  • CF exacerbations (inhaled form — Cayston): increased sputum, dyspnea, declining FEV₁, P. aeruginosa colonization
Setting: ICU (IV for gram-negative sepsis); OPD (inhaled form for CF)
Contraindications: Aztreonam allergy (cross-reactivity with ceftazidime and avibactam — avoid concurrent use); NO activity against gram-positive organisms or anaerobes — must combine for polymicrobial coverage; avoid as monotherapy for intra-abdominal infections
Adult Dose:
  • IV: 1–2 g IV q8–12h (serious: 2 g IV q6–8h)
  • Inhaled (CF): 75 mg nebulized TID × 28 days on/28 days off
Pediatric Dose:
  • IV: 90–120 mg/kg/day divided q6–8h (max 8 g/day)
  • Neonates: 60–120 mg/kg/day divided q8–12h (GA-adjusted)
  • Inhaled CF (≥7 years): 75 mg nebulized TID

38. Fosfomycin

Class: Phosphonic acid antibiotic
Indications & Clinical Signs/Symptoms:
  • Uncomplicated lower UTI (women): dysuria, frequency, urgency — single-dose oral convenience; effective against ESBL-producing E. coli
  • Complicated UTI/CAUTI (IV form for MDR organisms): fever, flank pain, catheter-related bacteriuria
  • MDR gram-negative infections (IV, combination therapy): ESBL-Klebsiella, carbapenem-resistant organisms
Setting: OPD (PO single-dose for uncomplicated UTI); ICU (IV for MDR organisms)
Contraindications: Fosfomycin allergy; contains sodium (caution in heart failure/hypertension — IV form especially); renal impairment (reduce dose); PO form NOT recommended for complicated UTI or pyelonephritis; resistance develops rapidly — combination essential for serious infections; ineffective against Pseudomonas as monotherapy
Adult Dose:
  • PO (uncomplicated UTI): 3 g granules in water as a single dose
  • IV (complicated UTI/MDR): 4–6 g IV q6–8h (up to 24 g/day for serious infections)
Pediatric Dose:
  • PO: Not established for children <12 years for granule form
  • IV: 100–200 mg/kg/day divided q6–8h (max 16 g/day); neonatal sepsis (MDR): 100–200 mg/kg/day divided q12h

39. Tigecycline

Class: Glycylcycline (tetracycline derivative)
Indications & Clinical Signs/Symptoms:
  • Complicated skin/soft tissue infections (polymicrobial, MRSA): deep wound infections, cellulitis, abscesses
  • Complicated intra-abdominal infections: peritonitis, abscess, mixed aerobic/anaerobic infections
  • Community-acquired pneumonia (atypicals, broad spectrum)
  • MDR Acinetobacter baumannii (salvage): VAP, bacteremia in ICU
  • ESBL-producing and carbapenem-resistant organisms (combination)
Setting: ICU (hospital use — MDR salvage); no oral form
Contraindications: Tetracycline allergy; FDA Black Box Warning: all-cause mortality increase vs. comparators (particularly for VAP/bacteremia — use only when alternatives unsuitable); pregnancy (fetal toxicity); children <8 years (dental/bone effects); NOT for UTI (inadequate urinary concentrations); pancreatitis (rare association); photosensitivity; hepatic dose adjustment (Child-Pugh C); nausea/vomiting very common (limit dose escalation)
Adult Dose:
  • Loading: 100 mg IV, then 50 mg IV q12h × 5–14 days
  • MDR Acinetobacter (high-dose regimen): 200 mg loading, then 100 mg IV q12h
Pediatric Dose:
  • 8–11 years: 1.2 mg/kg IV q12h (max 50 mg/dose)
  • 12–17 years: 50 mg IV q12h
  • Avoid <8 years (dental staining, bone effects)

40. Ceftazidime-Avibactam

Class: 3rd-generation cephalosporin + novel β-lactamase inhibitor (non-β-lactam)
Indications & Clinical Signs/Symptoms:
  • KPC-producing carbapenem-resistant Klebsiella pneumoniae (CRKP): bacteremia, HAP/VAP, UTI — multidrug-resistant, previous treatment failures
  • OXA-48-producing organisms
  • MDR Pseudomonas aeruginosa (aztreonam-susceptible strains)
  • Carbapenem-resistant Enterobacterales (CRE): fever, positive cultures from blood/urine/respiratory tract, organ dysfunction in critically ill patient
Setting: ICU (exclusively for MDR/XDR gram-negative infections)
Contraindications: Cephalosporin or avibactam allergy; NOT active against MBL (metallo-β-lactamase)-producing organisms (NDM, VIM, IMP) — use aztreonam-avibactam or cefiderocol for these; cross-reactive with aztreonam — caution in aztreonam allergy; renal dose adjustment mandatory; rapid resistance emergence can occur with inadequate dosing (extended infusion preferred); limited data on outpatient use
Adult Dose: 2.5 g (ceftazidime 2 g/avibactam 0.5 g) IV q8h (infused over 2h); renal: adjust based on CrCl
Pediatric Dose:
  • 3 months–18 years: 62.5 mg/kg IV q8h (max 2.5 g/dose) infused over 2h
  • Neonates/infants (<3 months): 50 mg/kg IV q8h (based on limited data)

ICU vs OPD Quick Reference Summary

#AntibioticPrimary SettingKey ICU IndicationKey OPD Indication
1AmoxicillinOPD—Otitis, sinusitis, strep, UTI
2Amoxicillin-ClavOPD/HospitalModerate SSTISinusitis, bite wounds
3AmpicillinICUListeria meningitis, enterococcal endocarditis—
4Pip-TazoICUNosocomial pneumonia, febrile neutropenia, peritonitis—
5CefalexinOPD—Cellulitis, UTI
6CefazolinHospitalMSSA bacteremia, surgical prophylaxis—
7CefuroximeOPD/HospitalModerate CAPSinusitis, Lyme, UTI
8CeftriaxoneICU/HospitalMeningitis, severe sepsisGonorrhea IM, typhoid
9CeftazidimeICUPseudomonas pneumonia/bacteremia—
10CefepimeICUFebrile neutropenia, HAP/VAP—
11CeftarolineHospitalMRSA SSTI—
12MeropenemICUMDR sepsis, meningitis—
13ImipenemICUPolymicrobial severe infections—
14ErtapenemHospital→OPDESBL infectionsOnce-daily outpatient completion
15VancomycinICU/OPDMRSA bacteremia/pneumonia/meningitisC. diff PO
16TeicoplaninHospital/ICUMRSA bacteremia, endocarditis—
17GentamicinICU/OPDGram-neg sepsis, endocarditis synergyPelvic infection (IM)
18AmikacinICUMDR gram-negative, MDR-TB—
19CiprofloxacinOPD/ICUAnthrax IV, PseudomonasUTI, prostatitis, osteomyelitis
20LevofloxacinOPD/ICULegionella pneumonia IVCAP, pyelonephritis
21MoxifloxacinOPD/Hospital—CAP, MDR-TB
22AzithromycinOPDIV atypical CAPChlamydia, pertussis, MAC
23ClarithromycinOPD—H. pylori, MAC, CAP
24ErythromycinOPDIV Legionella (historical)Campylobacter, diphtheria
25DoxycyclineOPD/ICUIV RMSF, anthraxLyme, Chlamydia, malaria
26MinocyclineOPD/ICUMDR Acinetobacter (salvage)Acne, MRSA skin
27TMP-SMXOPD/ICUIV high-dose PCP treatmentUTI, MRSA skin, PCP prophylaxis
28MetronidazoleOPD/ICUIV anaerobic infections, amoebic abscessBV, trichomoniasis, Giardia
29ClindamycinOPD/ICUIV TSS/necrotizing fasciitisMRSA skin, aspiration pneumonia
30LinezolidICU→OPDMRSA VAP, VREStep-down MRSA, MDR-TB
31DaptomycinICUMRSA bacteremia, right-sided endocarditis—
32ColistinICUXDR Acinetobacter/Pseudomonas, CRE—
33RifampicinOPD/ICUDevice biofilm infections (adjunct)TB, leprosy, meningococcal prophylaxis
34NitrofurantoinOPD—Uncomplicated UTI
35Nafcillin/FlucloxHospital/ICUMSSA bacteremia/endocarditisFlucloxacillin for skin infections
36IsoniazidOPD/ICUTB meningitisActive TB, LTBI
37AztreonamICU/OPDIV gram-neg sepsis (β-lactam allergy)Inhaled for CF
38FosfomycinOPD/ICUIV MDR gram-negative (combination)Single-dose UTI
39TigecyclineICUMDR Acinetobacter, polymicrobial SSTI—
40Ceftazidime-AvibactamICUCRE, KPC-Klebsiella, MDR Pseudomonas—

Key Prescribing Principles

Spectrum escalation (OPD → ICU): Narrow-spectrum (amoxicillin, cefalexin) → Broad-spectrum (ceftriaxone, pip-tazo) → Last-resort (colistin, ceftazidime-avibactam)
De-escalation: In ICU, always de-escalate within 48–72h once culture and sensitivity results are available.
TDM (Therapeutic Drug Monitoring) required for: Vancomycin (AUC-guided), aminoglycosides (peak/trough), linezolid (in prolonged courses).
Pediatric special cautions:
  • Fluoroquinolones: avoid <18 years (except anthrax, CF, plague, specific indications)
  • Tetracyclines: avoid <8 years (except RMSF — doxycycline is drug of choice at any age)
  • TMP-SMX: contraindicated <6–8 weeks
  • Nitrofurantoin: contraindicated <1 month
  • Vancomycin: requires neonatal dose adjustment based on gestational age
Pregnancy safety summary:
  • Relatively safer: amoxicillin, ampicillin, cephalosporins, azithromycin (2nd/3rd trimester), clindamycin
  • Avoid: fluoroquinolones, tetracyclines, TMP-SMX (1st & 3rd trimester), metronidazole (1st trimester), aminoglycosides (ototoxicity)
Sources: Goodman & Gilman's The Pharmacological Basis of Therapeutics; Katzung's Basic and Clinical Pharmacology 16e; Jawetz, Melnick & Adelberg's Medical Microbiology 28e; Lippincott Illustrated Reviews: Pharmacology; Harriet Lane Handbook 23e
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