Antimicrobial Agents - General Principles

Vocabulary flashcards covering the definitions, concepts, and principles of antimicrobial pharmacology.

Chemotherapy

The treatment of systemic infection with specific drugs that have selective toxicity for the infecting organism with no or minimal effect on the host cell.

Antibiotic

Substances produced by microorganisms which selectively suppress the growth or kill other microorganisms at very low concentrations.

Antimicrobial agent (AMA)

A term used to designate synthetic as well as naturally obtained drugs that destroy or inhibit the growth of microorganisms.

Bacteriostatic

Refers to drugs that can slow microbial growth but do not cause cell death, requiring host immune defenses to ultimately eliminate the bacteria.

Bactericidal

Refers to drugs that are directly lethal to bacteria at clinically achievable concentrations.

Natural resistance

Antimicrobial resistance that occurs because microbes natively lack the target site affected by a particular drug, such as Gram-negative bacteria being unaffected by penicillin G.

Acquired resistance

The process where an organism that was once responsive to an antibiotic becomes less susceptible or completely loses drug sensitivity over time.

Spontaneous mutation

Random changes in microbial DNA that produce a gradual increase in resistance, typically causing resistance to a single drug.

Conjugation

A process mainly in Gram-negative bacteria where extra-chromosomal DNA coding for resistance mechanisms is transferred from one bacterium to another, leading to multiple drug resistance.

Nosocomial infections

Infections acquired within hospital settings where resident organisms can become extremely drug-resistant and difficult to treat.

Superinfection

A new infection that appears during the course of treatment for a primary infection, often caused by broad-spectrum antimicrobials disrupting normal protective flora.

Empiric therapy

The initiation of antimicrobial treatment prior to receiving laboratory test results, based on clinical evaluation and knowledge of likely pathogens.

Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antimicrobial agent that results in the inhibition of visible bacterial growth.

Minimum Bactericidal Concentration (MBC)

The lowest concentration of an antimicrobial agent that kills $99.9\%$ of the original bacterial inoculum.