PTCE: The Basics of Medications - Anti-Infective Agents

Tip: Oral antibiotic agents may need to be reconstituted. These agents are mixed by the pharmacist or technician upon dispensing due to their short shelf life. Oral syringes or dosing spoons should also be dispensed with pediatric oral medications.

Table: USAN Stems for Anti-Infective Agents

Anti-infective agents, or antimicrobials, are agents that either kill microorganisms or slow the spread by inhibiting growth. These agents are classified as either bactericidal (kill the microorganisms) or bacteriostatic (inhibit the growth of the microorganisms). Antibiotics are agents produced by microorganisms and, at low concentrations, kill or inhibit the growth of bacteria.
Microorganisms most commonly include bacteria (antibacterial) and viruses (antiviral) but could also refer to fungi (antifungal) and protozoa (antiprotozoal). Selection of an agent depends on the following:
- Pathogen—determined via previous acquisition, antimicrobial testing, or from a disease state
- Drug—attributes to be considered include pharmacokinetics, pharmacodynamics, and toxicity
- Cost—low cost vs. high cost, insurance, and so on
- Administration—oral vs. I.V., hospital or home infusion, and so on
- Host—variables that must be considered include age, liver and/or kidney function, and immune status
Antibacterial agents are categorized by the spectrum of activity (Gram-positive and/or Gram-negative), bacterial effect (bactericidal or bacteriostatic), and mechanism of action.
The tables below provide information on the most commonly prescribed anti-infective drug classifications. Each table provides information on drug classifications, mechanisms of action, bacterial effects, spectrums of action, common indications and side effects, and the duration of therapy.

Table: Penicillins




Table: Cephalosporins




Table: Macrolides




Table: Tetracyclines




Table: Quinolones




Table: Ketolide





Table: Aminoglycosides




Table: Carbapenems and Monobactams



Miscellaneous Anti-Infective Agents
These agents, as outlined below, are used to treat a variety of infections. Proper selection of an agent is determined by an initial accurate diagnosis, the duration of therapy, the need for cost-effective agents, and individual host characteristics, including state of mind. Appropriate selection can maximize the effect of treatment while minimizing side effects and unintended consequences, such as microbial resistance.

Table: Miscellaneous Anti-Infective Agents