Empirical antimicrobial use in common syndromes

Red Flags

Sepsis with shock (SBP <90 despite fluids, lactate ≥4) — empirical broad-spectrum antimicrobials within 1 hour after blood cultures^[1]
Suspected bacterial meningitis (fever, headache, neck stiffness, altered mental status) — empirical ceftriaxone + vancomycin + ampicillin (if age >50) within 1 hour after CSF/blood cultures^[1]
Necrotising soft tissue infection (pain out of proportion, crepitus, skin necrosis) — emergent surgical exploration plus broad-spectrum antimicrobials^[1]
Healthcare-associated infection in patient with prior carbapenem exposure or MDR colonisation — narrow last-line agents (colistin, polymyxin B) and ID consult^[1]

Stewardship: review at 48–72 h^[1]
De-escalate to narrowest effective agent based on culture results; shorten duration; transition IV to PO; stop on resolution
Source control^[1]
Drain abscesses, remove infected lines/devices, debride necrotic tissue, treat obstruction — antimicrobials alone fail without source control

Drug	Class	Adult	Paediatric	Notes
Amoxicillin-clavulanate^[1]	Aminopenicillin + beta-lactamase inhibitor	625 mg PO TID or 1.2 g IV TDS for 5–7 days	25–45 mg/kg/day divided BD/TID (amoxicillin component)	Community-acquired LRTI, mild SSTI, animal bite, otitis media
Ceftriaxone^[1]	3rd-generation cephalosporin	1–2 g IV daily (2 g BD for meningitis)	50–100 mg/kg/day	Community-acquired pneumonia (severe), pyelonephritis, gonorrhoea, meningitis (with vancomycin)
Piperacillin-tazobactam^[1]	Antipseudomonal beta-lactam-inhibitor combination	4.5 g IV q8h (extended infusion preferred)	300 mg/kg/day divided q6h	Hospital-acquired pneumonia, intra-abdominal infection, sepsis with abdominal source, neutropenic fever
Meropenem^[1]	Carbapenem	1 g IV q8h (extended infusion 3 h preferred)	20–40 mg/kg/dose q8h	Reserve antibiotic — ESBL-producing organisms, severe HAP, septic shock with high MDR risk; de-escalate based on susceptibility
Vancomycin^[1]	Glycopeptide	15–20 mg/kg IV q8–12h, target trough 15–20 mg/L for severe MRSA	10–15 mg/kg q6h	Suspected/confirmed MRSA, VRE-active alternative is linezolid, severe SSTI requiring IV

Amoxicillin-clavulanate^[1]

Aminopenicillin + beta-lactamase inhibitor

Community-acquired LRTI, mild SSTI, animal bite, otitis media

Ceftriaxone^[1]

3rd-generation cephalosporin

Community-acquired pneumonia (severe), pyelonephritis, gonorrhoea, meningitis (with vancomycin)

Piperacillin-tazobactam^[1]

Antipseudomonal beta-lactam-inhibitor combination

Hospital-acquired pneumonia, intra-abdominal infection, sepsis with abdominal source, neutropenic fever

Meropenem^[1]

Carbapenem

Reserve antibiotic — ESBL-producing organisms, severe HAP, septic shock with high MDR risk; de-escalate based on susceptibility

Vancomycin^[1]

Glycopeptide

Suspected/confirmed MRSA, VRE-active alternative is linezolid, severe SSTI requiring IV

Take antibiotics only as prescribed; complete the course only when your clinician advises — many infections need shorter courses than historically given^[1]
Watch for severe diarrhoea, rash, jaundice, or breathing difficulty during antibiotic therapy — same-day medical review^[1]
Worsening symptoms despite 48–72 h of antibiotic — return for review; may need different agent^[1]

Sepsis with shock or end-organ failureICU/HDU; infectious diseases for tailored therapy^[1]
Suspected MDR organism (CRE, XDR-TB, C. auris, VRE)Infectious diseases / clinical microbiology for last-line agent selection^[1]
Recurrent or refractory infection despite appropriate first-lineInfectious diseases for source workup and resistance testing^[1]

ICMR-aligned empirical antimicrobial selection for common adult and paediatric clinical syndromes, with stewardship-based de-escalation.

1.ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2nd Edition, 2019; ICMR ASP Network updates) (2019)