Chemotherapy and Antimicrobial Drugs

Flashcards reviewing vocabulary and key concepts related to chemotherapy, antibiotics, and antimicrobial resistance.

Selective toxicity

Selectively finding and destroying pathogens without damaging the host

Chemotherapy

The use of chemicals to treat a disease

Antibiotic

A substance produced by a microbe that, in small amounts, inhibits another microbe

Antimicrobial drugs

Synthetic substances that interfere with the growth of microbes

Fleming's Discovery (1928)

Discovered penicillin, produced by Penicillium

Spectrum of activity

The range of microbial types a drug affects

Broad-spectrum antibiotics

Antibiotics that affect a broad range of Gram-positive or Gram-negative bacteria

Superinfection

Overgrowth of normal microbiota that is resistant to antibiotics

Bactericidal

Kill microbes directly

Bacteriostatic

Prevent microbes from growing

Penicillins

Prevent the synthesis of peptidoglycan

Chloramphenicol, erythromycin, streptomycin, tetracyclines

Target bacterial 70S ribosomes, inhibiting protein synthesis

Polypeptide antibiotics

Change membrane permeability

Antifungal drugs

Combine with membrane sterols

Sulfanilamide

Competes with para-aminobenzoic acid (PABA), stopping the synthesis of folic acid

Natural Penicillins

Extracted from Penicillium fungi cultures; examples: Penicillin G (injected) and Penicillin V (oral)

Semisynthetic penicillins

Contain chemically added side chains, making them resistant to penicillinases

Extended-spectrum penicillins

Effective against gram-negatives as well as gram-positives; e.g., Aminopenicillins: ampicillin, amoxicillin

Carbapenems

Broad-spectrum antibiotics; e.g., Imipenem, doripenem

Monobactam

Synthetic antibiotic with a single ring; low toxicity; works against only certain gram-negatives; e.g., Aztreonam

Cephalosporins

Work similar to penicillins; grouped according to their generation of development

Vancomycin

Last line against antibiotic-resistant MRSA

Tetracyclines

Interfere with the tRNA attachment to the ribosome; broad spectrum

Sulfonamides

Inhibit the synthesis of folic acid

Nystatin

A polyene antifungal drug most commonly used

Amphotericin B

A polyene antifungal drug used for treatment of systemic fungal infections but is toxic to the kidneys

Echinocandins

Antifungal drugs that inhibit the synthesis of fungal cell walls

Flucytosine

Antifungal drug that is a cytosine analog and interferes with RNA synthesis

Disk-diffusion method (Kirby-Bauer test)

Tests the effectiveness of chemotherapeutic agents; zone of inhibition around the disk determines sensitivity

E test

Determines the minimal inhibitory concentration (MIC)

Persister cells

Microbes with genetic characteristics allowing for their survival when exposed to an antibiotic

Superbugs

Bacteria that are resistant to large numbers of antibiotics

Beta lactamases

Enzymes that break the ring of penicillins and cephalosporins

Therapeutic index

risk versus benefit of using an antibiotic

Synergism

The effect of two drugs together is greater than the effect of either alone

Antagonism

The effect of two drugs together is less than the effect of either alone

Bacteriocins

antimicrobial peptides produced by bacteria

Phage therapy

using bacteriophage to treat infections