Chemotherapeutic Agents - Inside Host Flashcards
synthetic
a drug that is man-made, it is synthesized in the laboratory
semi-synthetic
a drug that is part man-made and part micro-made
2nd/3rd Generation Abx
ABX that have been modified by scientists to increase efficacy, reduce toxicity, or overcome resistance
Prophylaxis
a preventative treatment that is given to people who are at risk
Superinfection
an infxn occurring during antimicrobic therapy that is caused by an overgrowth of drug-resistant microorganisms
Chemotherapeutic Index
the ratio of the dose of the drug that is toxic to host compared with the minimum dose that is toxic to the pathogen. The bigger the number, the better (esp. above one)
if a drug is toxic to humans at 10mg & toxic to pathogen at 10mg, the TI is 1 (equally likely to kill host as well as pathogen)
Paul Ehrlich (1910)
developed synthetic arsenic drug, salvarsan, to treat syphillis
Alexander Fleming (1922)
discovered lysozyme in tears, saliva, and sweat. 1st body secretion proven to have chemotherapeutic properties
Alexander Fleming (1928)
discovered the first microbe-made drug or abx. Fungus penicillium made, made penicillin, which inhibited the bacterium Staphylococcus aureus
Sulfanomides (1930s)
were synthesized - still used today
Florey & Chain (1940s)
clinically tested penicillin and it was mass produced
Waksman (1944)
Soils! Discovered streptomycin (then chloramphenicol, tetracycline, erythromycin)
Phenol Coefficient Test
- Cultures are exposed to dilutions of test chemical for a standard time and the lowest effective dose is compared with that of phenol (carbolic acid). Coefficients >1 = chemical is more effective
uses Staphylococcus aureus and Pseudomonas aeruginosa
Minimum Inhibitory Count (MIC)/Minimum Bacterial Concentration (MBC)
- Dilution test using several test bacteria
- Broth cultures are exposed to dilutions of test chemical for standard time
- MIC: lowest concentration that will stop organism
- MBC: lowest concentration that will kill organism
Disc Diffusion Test (Kirby Bauer Test)
- test bacterium is seeded on plate and filter paper discs with different antimicrobials are placed on surface
- larger zones of inhibition = more effective antimicrobial
- Diameters are compared to standardized values and are classified as Senstivie, Intermediate, Resistant.
Antimicrobial Drugs
- Abx are relased by microbes to STOP growth of other microbes
- Inhibitory chemicals allow antibiotic-producing microbes to out-compete rivals for food and habitat
- Most abx are metabolic products of Molds (Penicillium and Cephalosporin) & Bacteria (Streptomyces and Bacillus)
Antibacterial Drugs
Penicillins
- MOA: Cell wall: blocks synthesis of peptidoglycan
- Originally Narrow spectrum and bactericidal (G+), Now broad spectrum
- All have β-lactam ring, little host toxicity, primary problems are allergies & R
- Ex: Amoxicillin, Ampicillin, Methicillin, Carbenicillin
Antibacterial Drugs
Cephalosporins
- MOA: Cell wall, blocks synthesis of peptidoglycan
- Broad-spectrum
- 1/3 of all abx administered, similar to penicillin, resistant to β-lactamases, fewer toxicity rxns, 2nd, 3rd, 4th gen more effective against G+&-, 6-carbon ring instead of 5
- Ex: Cephalosporin
