Antimicrobials

Mechanisms

Antimicrobial mechanism of action determines spectrum, resistance pattern, and characteristic adverse effects - see for the detailed mechanism-by-class breakdown (cell wall synthesis inhibitors, protein synthesis inhibitors, nucleic acid synthesis inhibitors, folate synthesis inhibitors)
Bactericidal agents (e.g. beta-lactams, aminoglycosides) directly kill target organisms, while bacteriostatic agents (e.g. macrolides, tetracyclines) inhibit growth/replication, relying on host immune clearance to eliminate the remaining organism burden - this distinction is occasionally clinically relevant (e.g. bactericidal agents generally preferred in immunocompromised hosts or in infections at sites with limited immune access, such as endocarditis)

Amongst the most widely prescribed medication classes globally, with antimicrobial stewardship an increasingly central prescribing consideration given rising resistance rates worldwide

Narrowest effective spectrum should be selected once culture/susceptibility results are available, per antimicrobial stewardship principles (see )
Renal/hepatic function-adjusted dosing is required for several classes (aminoglycosides, vancomycin, several beta-lactams) given predominantly renal clearance

Empirical broad-spectrum therapy pending culture results, followed by de-escalation to targeted narrow-spectrum therapy once organism and susceptibility are known - a core antimicrobial stewardship principle applied across essentially all antimicrobial prescribing

Beta-lactam allergy assessment and cross-reactivity (see ), aminoglycoside/vancomycin therapeutic drug monitoring, antimicrobial stewardship de-escalation principles
Antimicrobial selection should always progress from broad empirical cover (matched to the likely organism and local resistance patterns) to narrow, targeted therapy once culture and susceptibility results are available - continuing broad-spectrum treatment unnecessarily drives resistance selection pressure without added clinical benefit once a specific organism is identified

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