Introduction: This concise introduction covers the history and classification of antibiotics for B. Pharm students. It traces milestones from the early sulfonamides and Fleming’s discovery of penicillin to the “golden age” of antibiotic discovery, highlighting mechanisms of action, major chemical classes (beta-lactams, aminoglycosides, macrolides, tetracyclines, fluoroquinolones, glycopeptides, polymyxins), and classification by spectrum, mechanism, and bactericidal versus bacteriostatic activity. Emphasis is placed on clinical relevance, resistance mechanisms (beta-lactamases, efflux, target modification), pharmacokinetics/pharmacodynamics, and antimicrobial stewardship. This foundation prepares students for applied therapeutics and exam-style questions. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which scientist is credited with the discovery of penicillin?
- Gerhard Domagk
- Alexander Fleming
- Selman Waksman
- Paul Ehrlich
Correct Answer: Alexander Fleming
Q2. Which antibiotic class inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)?
- Aminoglycosides
- Macrolides
- Beta-lactams
- Fluoroquinolones
Correct Answer: Beta-lactams
Q3. Which of the following antibiotics is primarily bacteriostatic and inhibits the 50S ribosomal subunit by blocking the peptidyl transferase center?
- Gentamicin
- Chloramphenicol
- Ciprofloxacin
- Vancomycin
Correct Answer: Chloramphenicol
Q4. The “golden age” of antibiotic discovery refers mainly to which decades?
- 1920s–1930s
- 1940s–1960s
- 1970s–1980s
- 1990s–2000s
Correct Answer: 1940s–1960s
Q5. Which mechanism confers resistance by enzymatic inactivation of beta-lactam antibiotics?
- Efflux pumps
- Beta-lactamase production
- Ribosomal methylation
- Reduced permeability via porin loss
Correct Answer: Beta-lactamase production
Q6. Which antibiotic class is known for concentration-dependent killing and has a significant post-antibiotic effect?
- Beta-lactams
- Aminoglycosides
- Macrolides
- Sulfonamides
Correct Answer: Aminoglycosides
Q7. Which agent inhibits DNA gyrase and topoisomerase IV, interfering with bacterial DNA replication?
- Tetracycline
- Linezolid
- Ciprofloxacin
- Imipenem
Correct Answer: Ciprofloxacin
Q8. Extended-spectrum beta-lactamases (ESBLs) primarily hydrolyze which antibiotics?
- Glycopeptides
- Third-generation cephalosporins
- Macrolides
- Oxazolidinones
Correct Answer: Third-generation cephalosporins
Q9. Vancomycin exerts its action by:
- Inhibiting DNA gyrase
- Blocking peptidoglycan polymerization by binding D-Ala-D-Ala
- Disrupting the outer membrane of Gram-negative bacteria
- Inhibiting 30S ribosomal subunit
Correct Answer: Blocking peptidoglycan polymerization by binding D-Ala-D-Ala
Q10. Which antibiotic is associated with nephrotoxicity and ototoxicity and works by binding the 30S ribosomal subunit causing misreading?
- Tetracycline
- Gentamicin
- Clindamycin
- Rifampicin
Correct Answer: Gentamicin
Q11. Sulfonamides target which bacterial pathway?
- Cell wall synthesis
- Folate synthesis (dihydropteroate synthase)
- Protein synthesis at 50S ribosome
- RNA polymerase
Correct Answer: Folate synthesis (dihydropteroate synthase)
Q12. Which classification groups antibiotics by their chemical structure?
- Pharmacokinetic classification
- Mechanism-based classification
- Chemical class classification
- Therapeutic index classification
Correct Answer: Chemical class classification
Q13. Which antibiotic is contraindicated in children due to tooth discoloration and bone growth inhibition?
- Tetracycline
- Amoxicillin
- Azithromycin
- Linezolid
Correct Answer: Tetracycline
Q14. Time-dependent killing is a key pharmacodynamic feature of which class?
- Aminoglycosides
- Fluoroquinolones
- Beta-lactams
- Polymyxins
Correct Answer: Beta-lactams
Q15. Which antibiotic can cause “red man syndrome” when infused too rapidly?
- Vancomycin
- Ceftriaxone
- Doxycycline
- Metronidazole
Correct Answer: Vancomycin
Q16. Methicillin-resistant Staphylococcus aureus (MRSA) resistance is mainly due to:
- Beta-lactamase hyperproduction
- Acquisition of mecA gene encoding altered PBP (PBP2a)
- Efflux pump overexpression
- Porin loss
Correct Answer: Acquisition of mecA gene encoding altered PBP (PBP2a)
Q17. Which antibiotic class includes drugs that chelate divalent cations and should not be co-administered with milk or antacids?
- Tetracyclines
- Macrolides
- Beta-lactams
- Glycopeptides
Correct Answer: Tetracyclines
Q18. Carbapenems are best described as:
- Narrow-spectrum oral antibiotics
- Broad-spectrum beta-lactams resistant to many beta-lactamases
- Protein synthesis inhibitors targeting 50S ribosome
- Antimetabolites interfering with folate synthesis
Correct Answer: Broad-spectrum beta-lactams resistant to many beta-lactamases
Q19. Which mechanism reduces intracellular antibiotic concentration by actively transporting drugs out of the cell?
- Beta-lactamase activity
- Altered target site
- Efflux pumps
- Porin formation
Correct Answer: Efflux pumps
Q20. Which antibiotic is the drug of choice for treating infections caused by Pseudomonas aeruginosa among the following?
- Amoxicillin
- Piperacillin-tazobactam
- Vancomycin
- Doxycycline
Correct Answer: Piperacillin-tazobactam
Q21. Which class inhibits the 30S ribosomal subunit and prevents tRNA from binding to the A site?
- Macrolides
- Tetracyclines
- Glycopeptides
- Sulfonamides
Correct Answer: Tetracyclines
Q22. Plasmids that carry antibiotic resistance genes and can transfer between bacteria are called:
- Chromosomal integrons
- Transposons
- Conjugative plasmids
- Bacteriophages
Correct Answer: Conjugative plasmids
Q23. Which antibiotic class commonly causes QT interval prolongation as an adverse effect?
- Fluoroquinolones
- Aminoglycosides
- Beta-lactams
- Tetracyclines
Correct Answer: Fluoroquinolones
Q24. Metronidazole is particularly effective against which type of organisms?
- Anaerobic bacteria and some protozoa
- Obligate aerobes
- Mycobacteria
- Atypical intracellular bacteria
Correct Answer: Anaerobic bacteria and some protozoa
Q25. Which of the following tests determines the minimum concentration of antibiotic that inhibits visible bacterial growth?
- Minimal bactericidal concentration (MBC)
- Zone of inhibition test only
- Minimum inhibitory concentration (MIC)
- Serum bactericidal test
Correct Answer: Minimum inhibitory concentration (MIC)
Q26. Macrolides exert antibacterial action by binding to:
- 30S ribosomal subunit preventing initiation
- 50S ribosomal subunit blocking translocation
- DNA gyrase inhibiting replication
- Cell membrane causing depolarization
Correct Answer: 50S ribosomal subunit blocking translocation
Q27. Which antibiotic is commonly used to treat MRSA infections and belongs to the oxazolidinone class?
- Linezolid
- Clindamycin
- Cefazolin
- Amikacin
Correct Answer: Linezolid
Q28. Polymyxins act primarily by:
- Inhibiting protein synthesis at 50S
- Disrupting the bacterial cell membrane by interacting with LPS
- Blocking folate synthesis
- Inhibiting peptidoglycan cross-linking
Correct Answer: Disrupting the bacterial cell membrane by interacting with LPS
Q29. Antimicrobial stewardship programs primarily aim to:
- Increase antibiotic sales
- Optimize antibiotic use to reduce resistance and improve outcomes
- Promote broad-spectrum empiric therapy for all patients
- Replace infection control measures
Correct Answer: Optimize antibiotic use to reduce resistance and improve outcomes
Q30. Which of the following indicates intrinsic resistance?
- Plasmid-encoded beta-lactamase in E. coli
- Natural impermeability of Pseudomonas outer membrane to certain antibiotics
- Mutation-induced rifampicin resistance in Mycobacterium tuberculosis
- Acquisition of mecA gene by Staphylococcus aureus
Correct Answer: Natural impermeability of Pseudomonas outer membrane to certain antibiotics
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com