Chapter 20 – Antimicrobial Drugs: Core Vocabulary

A comprehensive set of vocabulary flashcards covering definitions, drug classes, mechanisms, and key terms from Chapter 20 on Antimicrobial Drugs.

Antibiotic

A substance produced by microorganisms that, in small amounts, inhibits the growth of other microbes.

Selective toxicity

The capacity of a drug to harm microbes without damaging the host.

Spectrum of antimicrobial activity

The range of microorganisms a drug can affect.

Broad-spectrum antibiotic

An antimicrobial effective against both Gram-positive and Gram-negative bacteria.

Superinfection

Opportunistic overgrowth of microbes that occurs after normal flora are destroyed by broad-spectrum drugs.

Bactericidal drug

An antimicrobial that kills bacteria outright.

Bacteriostatic drug

An antimicrobial that inhibits bacterial growth without directly killing the organism.

Inhibition of cell-wall synthesis

Drug action that weakens peptidoglycan, leading to bacterial lysis.

Inhibition of protein synthesis

Drug action targeting 70S ribosomes to block bacterial translation.

Injury to plasma membrane

Drug action that increases membrane permeability and causes loss of cell metabolites.

Inhibition of nucleic-acid synthesis

Drug action that blocks DNA replication or transcription in microbes.

Inhibition of essential metabolite synthesis

Drug action by competitive inhibition of enzymatic pathways (e.g., folic-acid synthesis).

β-lactam ring

Common structural feature in penicillins and related antibiotics responsible for cell-wall inhibition.

Penicillin G

Natural penicillin effective against most staphylococci, streptococci, and several spirochetes; destroyed by penicillinase.

Semisynthetic penicillins

Laboratory-modified penicillins such as methicillin, ampicillin, amoxicillin, and carbenicillin.

Penicillinase (β-lactamase)

Bacterial enzyme that breaks the β-lactam ring, inactivating penicillins.

Carbapenems

β-lactam antibiotics (e.g., Primaxin) with very broad activity and resistance to renal degradation.

Bacitracin

Topical polypeptide antibiotic effective against Gram-positive skin infections.

Vancomycin

Toxic glycopeptide used for penicillinase-producing staphylococci and streptococcal endocarditis.

Isoniazid (INH)

Antitubercular drug that blocks synthesis of mycolic acids in Mycobacterium cell walls.

Aminoglycosides

Protein-synthesis inhibitors (e.g., streptomycin) with broad spectrum; can be nephro- and ototoxic.

Tetracyclines

Broad-spectrum antibiotics that penetrate tissues; contraindicated in children and pregnancy due to teeth and liver effects.

Chloramphenicol

Broad-spectrum, bacteriostatic drug that may cause lethal aplastic anemia.

Erythromycin

Macrolide whose spectrum resembles penicillin G; drug of choice for legionellosis, strep, and staph in children.

Rifampin

Drug that inhibits bacterial RNA synthesis; useful for tuberculosis and leprosy, penetrates CSF and abscesses.

Polymyxin B

Polypeptide that disrupts bacterial plasma membranes by binding phospholipids.

Amphotericin B

Polyene antifungal that binds ergosterol, creating pores in fungal membranes.

Imidazoles

Antifungals (miconazole, clotrimazole) that inhibit ergosterol synthesis; used topically.

Fluconazole

Systemic azole antifungal for deep mycoses.

Griseofulvin

Antifungal that binds keratin; treats ringworm of skin, hair, and nails.

Amantidine

Antiviral that blocks viral entry into host cells; limited use in influenza prophylaxis.

Acyclovir

Guanosine analog antiviral for herpesvirus infections; halts viral DNA synthesis.

Ribavirin

Nucleoside analog used to treat severe RSV (rotavirus) pneumonia in infants.

Zidovudine (AZT)

Reverse-transcriptase inhibitor nucleoside analog for HIV/AIDS therapy.

Alpha interferon

Cytokine drug of choice for treating viral hepatitis.

Chloroquine

Synthetic derivative of quinine used against malaria parasites.

Metronidazole (Flagyl)

Antiprotozoan and anaerobic antibacterial that damages DNA.

Niclosamide

Antihelminthic that inhibits ATP production in tapeworms.

Mebendazole

Antihelminthic that disrupts microtubules in Ascaris and pinworms.

Sulfanilamide

PABA analog antimetabolite that blocks folic-acid synthesis in bacteria.

Mechanisms of drug resistance

Destruction/inactivation of drug, prevention of penetration, or alteration of target site.

Synergism

Condition where two drugs together produce a greater effect than either alone.

Antagonism

Condition where combined drugs are less effective than when used separately.