Antimicrobials: Classification MCQs With Answer

Antimicrobials: Classification MCQs With Answer

Antimicrobials are vital in B. Pharm education, covering antibiotics, antivirals, antifungals, and antiparasitics. This introduction explores classification by chemical structure, mechanism of action, spectrum of activity, and clinical use — key concepts like β-lactams, macrolides, aminoglycosides, fluoroquinolones, azoles, polyenes, and nucleoside analogues. Understanding pharmacodynamics (MIC, MBC, time- vs concentration-dependent killing), resistance mechanisms (enzymatic degradation, efflux pumps, target modification), and adverse effects is crucial for safe therapy and stewardship. These MCQs test in-depth knowledge of drug classes, targets, lab methods, and therapeutic considerations to prepare B. Pharm students for exams and clinical practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which antibiotic class inhibits bacterial cell wall synthesis by binding penicillin-binding proteins and blocking transpeptidation?

• Macrolides
• Fluoroquinolones
• Beta-lactams
• Aminoglycosides

Correct Answer: Beta-lactams

Q2. Which of the following is a glycopeptide antibiotic primarily used against Gram-positive bacteria including MRSA?

• Vancomycin
• Imipenem
• Ciprofloxacin
• Doxycycline

Correct Answer: Vancomycin

Q3. Which mechanism best describes bacteriostatic activity?

• Rapidly lysing bacterial cells
• Inhibiting bacterial growth and reproduction
• Increasing cell membrane permeability causing death
• Inhibiting mammalian protein synthesis

Correct Answer: Inhibiting bacterial growth and reproduction

Q4. Which class of antimicrobials targets the 30S ribosomal subunit causing misreading of mRNA?

• Macrolides
• Aminoglycosides
• Glycopeptides
• Beta-lactams

Correct Answer: Aminoglycosides

Q5. Time-dependent killing is characteristic of which antibiotic group?

• Aminoglycosides
• Fluoroquinolones
• Beta-lactams
• Polymyxins

Correct Answer: Beta-lactams

Q6. Which parameter measures the lowest concentration of drug that prevents visible bacterial growth?

• Therapeutic index
• Minimum inhibitory concentration (MIC)
• Post-antibiotic effect
• Breakpoint concentration

Correct Answer: Minimum inhibitory concentration (MIC)

Q7. Which resistance mechanism involves bacteria producing enzymes that hydrolyze the antibiotic?

• Efflux pump overexpression
• Enzymatic degradation
• Target modification
• Reduced permeability

Correct Answer: Enzymatic degradation

Q8. Which antibiotic class inhibits DNA gyrase and topoisomerase IV in bacteria?

• Tetracyclines
• Fluoroquinolones
• Macrolides
• Sulfonamides

Correct Answer: Fluoroquinolones

Q9. Which drug is a beta-lactamase-resistant penicillin used for penicillinase-producing staphylococci?

• Ampicillin
• Oxacillin
• Piperacillin
• Ticarcillin

Correct Answer: Oxacillin

Q10. Which antifungal class inhibits ergosterol synthesis by blocking 14-alpha-demethylase?

• Polyenes
• Echinocandins
• Azoles
• Allylamines

Correct Answer: Azoles

Q11. Which antiviral drug is a neuraminidase inhibitor used for influenza treatment?

• Acyclovir
• Oseltamivir
• Zidovudine
• Ribavirin

Correct Answer: Oseltamivir

Q12. Which antiparasitic is commonly used to treat giardiasis and anaerobic bacterial infections by DNA strand breakage?

• Chloroquine
• Metronidazole
• Albendazole
• Pyrimethamine

Correct Answer: Metronidazole

Q13. Which antibiotic class is associated with concentration-dependent killing and a significant post-antibiotic effect?

• Beta-lactams
• Tetracyclines
• Aminoglycosides
• Macrolides

Correct Answer: Aminoglycosides

Q14. Which drug inhibits folate synthesis by competitive antagonism of para-aminobenzoic acid (PABA)?

• Trimethoprim
• Sulfamethoxazole
• Linezolid
• Ceftazidime

Correct Answer: Sulfamethoxazole

Q15. Which class includes drugs that bind to the 50S ribosomal subunit and block translocation?

• Macrolides
• Tetracyclines
• Aminoglycosides
• Fluoroquinolones

Correct Answer: Macrolides

Q16. Which test is a disk diffusion method used to assess bacterial susceptibility to antibiotics?

• Broth microdilution
• Kirby-Bauer test
• E-test strip assay
• PCR resistance assay

Correct Answer: Kirby-Bauer test

Q17. Which antibiotic is known for causing red man syndrome if infused too rapidly?

• Vancomycin
• Ceftriaxone
• Azithromycin
• Daptomycin

Correct Answer: Vancomycin

Q18. Which of the following is a mechanism by which bacteria reduce intracellular antibiotic concentration?

• Target site overproduction
• Efflux pumps
• Ribosomal mutation increasing binding
• Increased membrane porins

Correct Answer: Efflux pumps

Q19. Which drug class interferes with peptidoglycan synthesis by binding to D-Ala-D-Ala termini?

• Glycopeptides
• Tetracyclines
• Macrolides
• Quinolones

Correct Answer: Glycopeptides

Q20. Which antimicrobials are primarily nephrotoxic and ototoxic at high doses?

• Macrolides
• Aminoglycosides
• Penicillins
• Azoles

Correct Answer: Aminoglycosides

Q21. Which antibiotic is a prototypical broad-spectrum tetracycline used in many infections?

• Doxycycline
• Gentamicin
• Linezolid
• Cefazolin

Correct Answer: Doxycycline

Q22. Which antimicrobial inhibits fungal cell wall synthesis by blocking beta-(1,3)-D-glucan synthase?

• Azoles
• Polyenes
• Echinocandins
• Flucytosine

Correct Answer: Echinocandins

Q23. Which antibiotic combination works synergistically by blocking sequential steps in folate synthesis?

• Amoxicillin-clavulanate
• Trimethoprim-sulfamethoxazole
• Piperacillin-tazobactam
• Ampicillin-gentamicin

Correct Answer: Trimethoprim-sulfamethoxazole

Q24. Which enzyme produced by bacteria confers resistance by acetylation of aminoglycosides?

• Beta-lactamase
• Aminoglycoside acetyltransferase
• DNA gyrase
• Transpeptidase

Correct Answer: Aminoglycoside acetyltransferase

Q25. Which antibiotic is least likely to be effective against intracellular pathogens due to poor cell penetration?

• Macrolides
• Tetracyclines
• Aminoglycosides
• Fluoroquinolones

Correct Answer: Aminoglycosides

Q26. Which antitubercular drug inhibits mycolic acid synthesis in Mycobacterium tuberculosis?

• Isoniazid
• Rifampicin
• Ethambutol
• Pyrazinamide

Correct Answer: Isoniazid

Q27. Which antibiotic class commonly causes tendonitis and tendon rupture as an adverse effect?

• Macrolides
• Fluoroquinolones
• Beta-lactams
• Glycopeptides

Correct Answer: Fluoroquinolones

Q28. Which antiviral is a nucleoside reverse transcriptase inhibitor (NRTI) used in HIV therapy?

• Ritonavir
• Efavirenz
• Zidovudine
• Oseltamivir

Correct Answer: Zidovudine

Q29. Which antimicrobial class includes drugs that disrupt bacterial cell membrane integrity by interacting with lipopolysaccharides?

• Polymyxins
• Macrolides
• Beta-lactams
• Tetracyclines

Correct Answer: Polymyxins

Q30. Which laboratory value helps determine therapeutic dosing by measuring drug concentration relative to MIC?

• Area under the curve to MIC ratio (AUC/MIC)
• Prothrombin time
• Serum creatinine clearance only
• White blood cell count

Correct Answer: Area under the curve to MIC ratio (AUC/MIC)

Q31. Which antifungal binds ergosterol creating membrane pores leading to fungal cell death?

• Fluconazole
• Amphotericin B
• Terbinafine
• Voriconazole

Correct Answer: Amphotericin B

Q32. Which oral antibiotic is associated with photosensitivity and discoloration of developing teeth in children?

• Tetracyclines
• Penicillin V
• Ciprofloxacin
• Clindamycin

Correct Answer: Tetracyclines

Q33. Which mechanism leads to methicillin resistance in Staphylococcus aureus (MRSA)?

• Beta-lactamase overproduction only
• Altered penicillin-binding protein (PBP2a) expression
• Increased cell permeability
• Efflux of glycopeptides

Correct Answer: Altered penicillin-binding protein (PBP2a) expression

Q34. Which antibiotic is used as empirical therapy for Pseudomonas aeruginosa and is a fourth-generation cephalosporin?

• Cefepime
• Cefazolin
• Cefuroxime
• Ceftriaxone

Correct Answer: Cefepime

Q35. Which drug class can cause serotonin syndrome when combined with selective serotonin reuptake inhibitors (SSRIs)?

• Macrolides
• Oxazolidinones (e.g., linezolid)
• Aminoglycosides
• Beta-lactams

Correct Answer: Oxazolidinones (e.g., linezolid)

Q36. Which pharmacokinetic property most influences dosing frequency of time-dependent antibiotics?

• Peak plasma concentration (Cmax)
• Half-life and time above MIC (T>MIC)
• Volume of distribution only
• Protein binding exclusively

Correct Answer: Half-life and time above MIC (T>MIC)

Q37. Which antimalarial drug interferes with heme detoxification in Plasmodium species?

• Ivermectin
• Chloroquine
• Albendazole
• Metronidazole

Correct Answer: Chloroquine

Q38. Which antibiotic is most appropriate for treating methicillin-sensitive Staphylococcus aureus (MSSA) bloodstream infection?

• Oxacillin (or nafcillin)
• Vancomycin
• Azithromycin
• Ciprofloxacin

Correct Answer: Oxacillin (or nafcillin)

Q39. Which antifungal is an oral allylamine used to treat dermatophyte infections by inhibiting squalene epoxidase?

• Fluconazole
• Terbinafine
• Amphotericin B
• Flucytosine

Correct Answer: Terbinafine

Q40. Which mechanism of antiviral drug action is exemplified by acyclovir?

• Neuraminidase inhibition
• Viral DNA polymerase chain termination after phosphorylation
• Protease inhibition
• Integrase inhibition

Correct Answer: Viral DNA polymerase chain termination after phosphorylation

Q41. Which antibiotic is commonly used for anaerobic intra-abdominal infections and inhibits DNA synthesis in anaerobes?

• Metronidazole
• Ceftriaxone
• Azithromycin
• Trimethoprim

Correct Answer: Metronidazole

Q42. Which class of antibiotics shows cross-resistance often due to methylation of 23S rRNA?

• Macrolides, lincosamides, and streptogramin B (MLSB)
• Aminoglycosides only
• Beta-lactams only
• Fluoroquinolones only

Correct Answer: Macrolides, lincosamides, and streptogramin B (MLSB)

Q43. Which drug is indicated for serious Gram-negative infections and is a carbapenem with broad-spectrum activity?

• Imipenem
• Vancomycin
• Doxycycline
• Linezolid

Correct Answer: Imipenem

Q44. Which antimicrobial is a topical polyene used for cutaneous candidiasis?

• Clotrimazole
• Amphotericin B oral
• Terbinafine oral
• Fluconazole intravenous

Correct Answer: Clotrimazole

Q45. Which antibiotic inhibits protein synthesis by binding to the 50S subunit and is useful for anaerobic and certain Gram-positive infections but associated with C. difficile risk?

• Clindamycin
• Tetracycline
• Gentamicin
• Ciprofloxacin

Correct Answer: Clindamycin

Q46. Which pharmacodynamic parameter best predicts efficacy for aminoglycosides?

• Time above MIC (T>MIC)
• Peak/MIC ratio (Cmax/MIC)
• Protein binding
• Volume of distribution

Correct Answer: Peak/MIC ratio (Cmax/MIC)

Q47. Which antiprotozoal is the drug of choice for severe malaria due to Plasmodium falciparum in many settings?

• Artemisinin derivatives
• Chloroquine
• Mebendazole
• Metronidazole

Correct Answer: Artemisinin derivatives

Q48. Which antibiotic is a synthetic bacteriostatic oxazolidinone effective against multidrug-resistant Gram-positive cocci?

• Linezolid
• Vancomycin
• Cefotaxime
• Gentamicin

Correct Answer: Linezolid

Q49. Which laboratory method quantitatively determines MIC using serial dilutions in broth?

• Disk diffusion (Kirby-Bauer)
• Broth microdilution
• Gram staining
• ELISA for toxins

Correct Answer: Broth microdilution

Q50. Which strategy is recommended to reduce development of antimicrobial resistance in clinical practice?

• Empiric broad-spectrum therapy for all infections indefinitely
• Appropriate antimicrobial stewardship including targeted therapy and de-escalation
• Use antibiotics as prophylaxis for viral infections
• Avoid susceptibility testing to save resources

Correct Answer: Appropriate antimicrobial stewardship including targeted therapy and de-escalation

G S Sachin

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