Control of Microorganisms and Antimicrobial Chemotherapy
1. Define:
Cidal - Any treatment designed to kill the cells or organisms present is said to be cidal. Examples of cidal substances include insecticides, bactericides and fungicides.
Antiseptic - An antiseptic is a chemical substance used to kill or inhibit the growth of pathogenic microorganisms on living surfaces. Alcohol (isopropanol), betadine and zinc oxide are antiseptics commonly used on skin surfaces.
Disinfectant - A disinfectant is a chemical substance used to kill or inhibit growth of pathogenic microorganisms on non-living surfaces. Disinfectants are often significantly more toxic than antiseptics because they are not designed for use on living surfaces.
Antibiotic - An antibiotic is an antimicrobial agent (i.e., chemical designed to be used systemically to kill or inhibit the growth of pathogenic microorganisms) that was initially produced by microorganisms; usually bacteria or fungi (e.g., penicillin and streptomycin)
Penicillinase - Penicillinase enzymes are a specific type of beta-lactamase enzymes that degrade penicillins and allow organisms producing them to be drug-resistant (penicillin-resistant).
2. cidal/sterilized
3. sterilized
4. static/ freezing (Filtration can also be considered as static.)
5. These processes will kill most vegetative cells, but will not kill stearothermophiles/hyperthermophiles or the endospores formed by such bacteria. If any cells remain viable within a sample of liquid, that liquid cannot be considered sterile.
6. Tyndallization/ autoclave/ bacteristatic
7. ionizing radiation (x-ray or gamma ray)/ poses a hazard to individuals that must apply it.
8. filtration
9. disinfectants/ antimicrobial
10. effective within a reasonable time period/ biodegradable
11. If the chemical was going to be effective in controlling the pathogens present. If or not the chemical might be hazardous to handle, apply or come in contact with. If the chemical was likely to damage the surface or material it was being used on. If the chemical might accumulate in the environment and cause toxic side effects.
12. disinfectant
13. antiseptic/ disinfectant
14. G, I, K, B, J, C, F, E, D, A
15. surfactants/ halogens
16. antimicrobial/ antibiotics
17. Streptomyces and Bacillus
18. therapeutic/ If present in too low a concentration, the drug will not be effective in controlling the pathogens. If present in too high a concentration, the drug may cause toxic side effects that damage host cells, tissues, or organs.
19. narrow spectrum
20. differential toxicity/ broad spectrum/ A broad spectrum drug will kill many of the bacteria making up the normal flora. These bacteria play an important role in defending the body against potential pathogens, and their removal will have a negative impact on immune function.
21. acting as competitive inhibitors of an enzymatic pathway essential for prokaryotic cell growth (the conversion of para-aminobenzoic acid or PABA into folic acid).
22. sulfa drugs/ para-aminobenzoic acid (PABA) into folic acid
23. Penicillins and Cephalosporins (beta-lactam antibiotics)/ inhibiting protein synthesis
24. peptidoglycan cell walls/ differential toxicity
25. inhibit the formation of peptidoglycan, a component necessary to cell wall synthesis./ penicillinase or beta-lactamase
26. Aminoglycosides/ Tetracyclines
27. Tetracyclines and aminoglycosides/ cell membrane
28. tetracyclines/ static/ If these drugs remain within the body for an extended period of time (the recommended treatment period) they can prevent the bacteria from reproducing and give the body a chance to eliminate them. Human WBCs such as monocytes and neutrophils will eliminate the bacteria over time if the bacteria cannot reproduce faster than they are being removed.
29. binding permanently to ribosomes and blocking translation/ Streptomyces
30. Bacillus/ acting on cell membranes (increasing their permeability) and by interfering with the function of the outer membrane of the cell wall.
31. m-RNA synthesis (nucleic acid synthesis)
32. rifampin or actinomycin D
33. If these recommendations are not followed, the concentration of the drug within the body or the length of time the drug is present will not be sufficient to control the pathogen. If the pathogen population is continually exposed to low concentrations of antimicrobial drugs, any drug resistant mutants will be selected for, i.e., if such mutants arise within the population, their competition will be reduced and they will grow more readily. This could ultimately lead to the development of pathogenic strains that are entirely drug resistant.
34. Most antimicrobial drugs are not effective against viruses because their mechanisms of action involve components that viruses do not have (e.g., cell walls, cell membranes, enzymatic pathways and ribosomes).
Copyright 2002 Sierra College Biological Sciences Department
Last updated: 01/18/02.
