Q.1 Which of the following antibiotics inhibits bacterial cell wall synthesis?
Tetracycline
Penicillin
Rifampicin
Erythromycin
Explanation - Penicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to cell lysis.
Correct answer is: Penicillin
Q.2 Which class of antimicrobial agents is primarily bacteriostatic rather than bactericidal?
Aminoglycosides
Macrolides
Beta-lactams
Fluoroquinolones
Explanation - Macrolides inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit, generally resulting in bacteriostatic action.
Correct answer is: Macrolides
Q.3 Ciprofloxacin belongs to which class of antibiotics?
Sulfonamides
Fluoroquinolones
Tetracyclines
Glycopeptides
Explanation - Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA gyrase and topoisomerase IV, preventing DNA replication.
Correct answer is: Fluoroquinolones
Q.4 Which of the following is effective against Mycobacterium tuberculosis?
Amoxicillin
Isoniazid
Azithromycin
Ceftriaxone
Explanation - Isoniazid is a first-line anti-tuberculosis drug that inhibits mycolic acid synthesis, essential for the bacterial cell wall of Mycobacterium tuberculosis.
Correct answer is: Isoniazid
Q.5 Which antibiotic is commonly associated with nephrotoxicity and ototoxicity?
Gentamicin
Amoxicillin
Cefalexin
Erythromycin
Explanation - Gentamicin, an aminoglycoside, can accumulate in the kidneys and inner ear, causing nephrotoxicity and ototoxicity.
Correct answer is: Gentamicin
Q.6 Sulfonamides inhibit bacterial growth by interfering with which metabolic pathway?
Folate synthesis
Peptidoglycan synthesis
Protein synthesis
DNA gyrase activity
Explanation - Sulfonamides are structural analogs of PABA and inhibit dihydropteroate synthase, blocking folate synthesis, which is essential for nucleotide formation.
Correct answer is: Folate synthesis
Q.7 Which of the following antibiotics is classified as a glycopeptide?
Vancomycin
Ciprofloxacin
Clindamycin
Doxycycline
Explanation - Vancomycin is a glycopeptide antibiotic that inhibits cell wall synthesis by binding to D-Ala-D-Ala terminus of peptidoglycan precursors.
Correct answer is: Vancomycin
Q.8 Which antimicrobial is known for causing the 'red man syndrome' if infused too quickly?
Vancomycin
Penicillin G
Ceftriaxone
Linezolid
Explanation - Rapid infusion of vancomycin can trigger histamine release, leading to flushing, rash, and hypotension known as 'red man syndrome'.
Correct answer is: Vancomycin
Q.9 Which antibiotic interferes with bacterial 30S ribosomal subunit?
Tetracycline
Erythromycin
Chloramphenicol
Vancomycin
Explanation - Tetracyclines bind to the 30S ribosomal subunit, blocking attachment of tRNA and inhibiting protein synthesis.
Correct answer is: Tetracycline
Q.10 Which antibiotic is primarily used for anaerobic bacterial infections?
Metronidazole
Ciprofloxacin
Gentamicin
Amoxicillin
Explanation - Metronidazole is reduced in anaerobic bacteria and protozoa, generating toxic metabolites that damage DNA.
Correct answer is: Metronidazole
Q.11 Which of the following antibiotics is a beta-lactamase inhibitor?
Clavulanic acid
Cefotaxime
Tetracycline
Erythromycin
Explanation - Clavulanic acid inhibits beta-lactamase enzymes, protecting beta-lactam antibiotics from enzymatic degradation.
Correct answer is: Clavulanic acid
Q.12 Which of the following is a major side effect of chloramphenicol?
Aplastic anemia
Ototoxicity
Peripheral neuropathy
Tendon rupture
Explanation - Chloramphenicol can cause dose-independent aplastic anemia, a rare but potentially fatal condition.
Correct answer is: Aplastic anemia
Q.13 Which antibiotic class is known to cause photosensitivity as a common adverse effect?
Tetracyclines
Aminoglycosides
Macrolides
Beta-lactams
Explanation - Tetracyclines can cause photosensitivity, making the skin more susceptible to sunburn.
Correct answer is: Tetracyclines
Q.14 Which of the following is a broad-spectrum antibiotic effective against both Gram-positive and Gram-negative bacteria?
Ampicillin
Penicillin V
Vancomycin
Rifampicin
Explanation - Ampicillin is a broad-spectrum penicillin that can target both Gram-positive and certain Gram-negative bacteria.
Correct answer is: Ampicillin
Q.15 Which antibiotic is commonly used for prophylaxis in bacterial endocarditis?
Amoxicillin
Metronidazole
Ceftriaxone
Gentamicin
Explanation - Amoxicillin is used prophylactically to prevent bacterial endocarditis in high-risk patients undergoing dental or surgical procedures.
Correct answer is: Amoxicillin
Q.16 Linezolid belongs to which class of antibiotics?
Oxazolidinones
Macrolides
Tetracyclines
Fluoroquinolones
Explanation - Linezolid is an oxazolidinone antibiotic that inhibits protein synthesis by binding to the 50S ribosomal subunit.
Correct answer is: Oxazolidinones
Q.17 Which of the following drugs is effective against Pseudomonas aeruginosa?
Piperacillin
Amoxicillin
Erythromycin
Clindamycin
Explanation - Piperacillin, an extended-spectrum penicillin, is active against Pseudomonas aeruginosa, unlike most other penicillins.
Correct answer is: Piperacillin
Q.18 Which antibiotic inhibits bacterial DNA-dependent RNA polymerase?
Rifampicin
Ciprofloxacin
Tetracycline
Vancomycin
Explanation - Rifampicin binds to the beta-subunit of bacterial RNA polymerase, inhibiting RNA synthesis.
Correct answer is: Rifampicin
Q.19 Which of the following antibiotics is used to treat MRSA infections?
Vancomycin
Penicillin G
Cefalexin
Amoxicillin
Explanation - Vancomycin is effective against methicillin-resistant Staphylococcus aureus (MRSA) by inhibiting cell wall synthesis.
Correct answer is: Vancomycin
Q.20 Which antibiotic can cause tendon rupture as a serious adverse effect?
Levofloxacin
Erythromycin
Amoxicillin
Chloramphenicol
Explanation - Levofloxacin, a fluoroquinolone, has been associated with tendonitis and tendon rupture, particularly in elderly patients.
Correct answer is: Levofloxacin
Q.21 Which antibiotic is effective against atypical organisms like Mycoplasma pneumoniae?
Azithromycin
Penicillin G
Vancomycin
Ceftriaxone
Explanation - Azithromycin, a macrolide, is effective against atypical pathogens that lack a cell wall, such as Mycoplasma pneumoniae.
Correct answer is: Azithromycin
Q.22 Which of the following antibiotics is commonly used to treat urinary tract infections caused by E. coli?
Nitrofurantoin
Vancomycin
Tetracycline
Rifampicin
Explanation - Nitrofurantoin concentrates in the urine and is effective against common uropathogens like E. coli.
Correct answer is: Nitrofurantoin
Q.23 Which antimicrobial class works by inhibiting bacterial topoisomerase enzymes?
Fluoroquinolones
Beta-lactams
Macrolides
Glycopeptides
Explanation - Fluoroquinolones inhibit DNA gyrase (topoisomerase II) and topoisomerase IV, preventing DNA replication.
Correct answer is: Fluoroquinolones
Q.24 Which of the following antibiotics is effective against anaerobic protozoa as well as anaerobic bacteria?
Metronidazole
Ciprofloxacin
Amoxicillin
Gentamicin
Explanation - Metronidazole is reduced under anaerobic conditions, producing toxic metabolites that damage DNA in both anaerobic bacteria and protozoa.
Correct answer is: Metronidazole