Key Terms
Chemotherapy
Any use of chemicals or drugs to treat disease; NOT limited to cancer treatment. Antimicrobial drug: a chemical that kil
Bacteriostatic
Reversibly inhibits growth; bacteria resume growing when drug is removed. Bactericidal: kills bacteria; irreversible.
Narrow-spectrum
Targets only specific subsets (e.g., gram-positive only, or gram-negative only).
Broad-spectrum
Targets both gram-positive and gram-negative species.
Use broad-spectrum when
1. Empiric therapy needed (pathogen not yet identified).
Risk of broad-spectrum use
Superinfection.
Superinfection
A secondary infection that develops because broad- spectrum antibiotics kill protective normal microbiota, allowing a re
Dosage
Amount of drug given per time interval; must achieve therapeutic levels at infection site without causing significant si
Synergistic interaction
Combined effect of two drugs is greater than either alone.
Antagonistic interaction
Drugs interfere with each other; outcomes include loss of activity, decreased therapeutic levels, or increased toxicity.
Selective toxicity
Drug harms target microbe but not the host. Bacteria provide more unique targets than fungi, parasites, or viruses becau
EXCEPTION
Human mitochondria have 70S ribosomes; some antibiotics (notably chloramphenicol) can affect them — explains certain sid
Key concept
Antimetabolites are competitive inhibitors of bacterial metabolic enzymes.
Primary fungal target
Ergosterol (main sterol in fungal cell membranes, replaces cholesterol used in human cells).
Atovaquone
Blocks electron transport (see above); also antiprotozoan.