1. What are the different
mechanisms of action of antibiotics?
- Inhibition of cell wall synthesis.
- Alteration of cell membrane function.
- Inhibition of protein synthesis.
- Inhibition of nucleic acid synthesis.
2. Name the antibiotics that inhibit cell wall synthesis.
- Penicillins, cephalosporins, vancomycin, bacitracin and
cycloserine.
3. Name the antibiotics that alter cell membrane function.
- Colistin, Polymyxin, Amphotericin B and Nystatin.
4. Name the antibiotics that inhibit protein synthesis.
- Chloramphenicol, Erythromycin, Clindamycin, Tetracycline and
Aminoglycosides.
5. Name the antibiotics that inhibit nucleic acid synthesis.
- Sulphonamide, Trimethoprim, Quinolones and Rifampin.
6. What are the different methods of drug resistance in
bacteria?
- Production of enzymes that inactivate the drug. Eg:
β-lactamase, Chloramphenicol transacetylase.
- Production of new or modified targets with little or no affinity
for the drug. Eg: Resistance to penicillin by MRSA, resistance to
Streptomycin and Erythromycin.
- Decreased membrane permeability and active efflux. Eg:
Resistance to Tetracycline.
7. What is the genetic basis of drug resistance?
- Chromosomal mutations.
- Acquisition of plasmid or transposon, containing gene coding for
drug resistance.
8. What is intrinsic and acquired resistance?
- A bacterium found resistant to an antibiotic since the very
beginning is intrinsically resistant to that antibiotic. Eg:
Novobiocin resistance in S.saprophyticus.
- A bacterium acquiring resistance to an antibiotic through
plasmid, transposon or due to a chromosomal mutation is acquired
resistance. Eg: Penicillin resistance.
9. What are the methods of antibiotic susceptibility testing?
- Micro-broth and Macro-broth dilution method.
- Agar dilution method.
- Disk diffusion method.
- E test
- Automated systems10. What are MIC & MBC?
- MIC is minimum inhibitory concentration. It is the highest
dilution of an antibiotic that inhibits the growth of bacteria.
- MBC is minimum bactericidal concentration. It is the highest
dilution of an antibiotic that kills the bacteria.
11. Name two drugs, when given in combination, are additive or
synergistic.
- Penicillin and Gentamicin; Amoxycillin and Clavulanic acid;
Trimethoprim and sulphamethoxazole. ( Several drugs are given
together in the treatment of tuberculosis to achieve synergistic
killing and to prevent the emergence of drug resistance against
any one of them)
12. Name two drugs, when given in combination, are
antagonistic.
- Penicillin and Tetracycline (since one is bactericidal and
the other is bacteriostatic).
13. Name some bactericidal and bacteriostatic drugs.
- Penicillins, Cephalosporins, Aminoglycosides etc., are
bactericidal while Chloramphenicol and Tetracycline are
bacteriostatic.
14. Which is the enzyme that degrades penicillin ring?
- β-lactamase ( penicillinase )
15. When is a bacterium called “Multi- drug Resistant”?
- When a bacterium develops acquired resistance to three or
more standard antibiotics, it is said to have developed multi drug
resistance. This feature is common in Staphylococcus aureus,
Salmonella typhi and Mycobacterium tuberculosis.
16. Name some B-lactamase inhibitors.
- Clavulanic acid, Sulbactam and Tazobactam.
17. Name antibiotics used for topical application?
- Bacitracin, Neomycin and Mupirocin.
|
