Assessment of new antibiotics MCQs With Answer

Assessment of new antibiotics MCQs With Answer

The assessment of new antibiotics MCQs with answer is a focused study tool for B. Pharm students preparing for exams and practical evaluations. This introduction covers key concepts like mechanism of action, antimicrobial spectrum, MIC/MBC determination, pharmacokinetics/pharmacodynamics (PK/PD), susceptibility testing, resistance mechanisms, preclinical assays, and regulatory considerations. These SEO-rich materials help learners master laboratory methods, clinical trial phases, safety profiling, and interpretation of breakpoints for effective antibiotic evaluation. Designed to boost retention and exam performance, this resource aligns academic knowledge with real-world drug development processes. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which assay primarily determines the minimum inhibitory concentration (MIC) of a new antibiotic?

• Disk diffusion method
• Broth microdilution assay
• PCR-based resistance detection
• Time-kill curve

Correct Answer: Broth microdilution assay

Q2. What does MIC represent in antibiotic assessment?

• The concentration that kills 99.9% of bacteria
• The lowest concentration that inhibits visible bacterial growth
• The time taken to reduce bacterial count by half
• The maximum safe plasma concentration in humans

Correct Answer: The lowest concentration that inhibits visible bacterial growth

Q3. Which parameter describes bactericidal activity rather than bacteriostatic effect?

• MIC
• MBC (Minimum Bactericidal Concentration)
• Zone diameter in disk diffusion
• Post-antibiotic effect duration

Correct Answer: MBC (Minimum Bactericidal Concentration)

Q4. Which pharmacodynamic index best predicts the efficacy of concentration-dependent antibiotics?

• Time above MIC (T>MIC)
• Area under the concentration-time curve to MIC ratio (AUC/MIC)
• Peak/MIC (Cmax/MIC)
• Post-antibiotic effect length

Correct Answer: Peak/MIC (Cmax/MIC)

Q5. In checkerboard assays, fractional inhibitory concentration (FIC) index is used to evaluate:

• Bacterial mutation rates
• Synergy or antagonism between two antibiotics
• Pharmacokinetic interactions in plasma
• Rate of spontaneous resistance

Correct Answer: Synergy or antagonism between two antibiotics

Q6. Time-kill studies primarily measure which aspect of an antibiotic?

• Long-term toxicity
• Rate and extent of bacterial killing over time
• Serum protein binding
• Genetic mechanisms of resistance

Correct Answer: Rate and extent of bacterial killing over time

Q7. Which test is standard for determining susceptibility in routine clinical labs due to simplicity?

• Broth microdilution
• Time-kill assay
• Disk diffusion (Kirby-Bauer)
• Checkerboard titration

Correct Answer: Disk diffusion (Kirby-Bauer)

Q8. Which regulatory phase involves initial human dosing to assess safety of a new antibiotic?

• Preclinical toxicology
• Phase I clinical trials
• Phase II clinical trials
• Phase III clinical trials

Correct Answer: Phase I clinical trials

Q9. Which measurement helps determine whether an antibiotic is likely to reach effective concentrations at the infection site?

• MIC alone
• Volume of distribution (Vd) and tissue penetration data
• Disk diffusion zone size
• Bacterial colony morphology

Correct Answer: Volume of distribution (Vd) and tissue penetration data

Q10. What is the main purpose of determining pharmacokinetic/pharmacodynamic (PK/PD) targets for antibiotics?

• To identify mechanisms of resistance
• To guide dosing regimens that maximize efficacy and minimize resistance
• To replace clinical trials
• To measure in vitro zone diameters

Correct Answer: To guide dosing regimens that maximize efficacy and minimize resistance

Q11. In assessing new antibiotics, what does the term “breakpoint” refer to?

• The maximum tolerated dose in animals
• The MIC value that separates susceptible from resistant strains clinically
• The time to first detectable adverse event
• The molecular weight cutoff for renal excretion

Correct Answer: The MIC value that separates susceptible from resistant strains clinically

Q12. Which preclinical model is commonly used to study antibiotic efficacy in a systemic bacterial infection?

• Patch-clamp electrophysiology
• Murine (mouse) septicemia model
• Human cell line MIC testing
• In silico docking only

Correct Answer: Murine (mouse) septicemia model

Q13. Which resistance mechanism involves enzymatic drug modification or degradation?

• Target site mutation
• Efflux pump overexpression
• Enzymatic inactivation (e.g., beta-lactamases)
• Reduced membrane permeability

Correct Answer: Enzymatic inactivation (e.g., beta-lactamases)

Q14. For time-dependent antibiotics, which dosing principle is most important?

• Maximize Cmax relative to MIC
• Prolong time above MIC (T>MIC)
• Minimize AUC
• Administer only once daily regardless of half-life

Correct Answer: Prolong time above MIC (T>MIC)

Q15. Which of the following best describes post-antibiotic effect (PAE)?

• Immediate bacterial regrowth during antibiotic exposure
• Persistent suppression of bacterial growth after antibiotic removal
• Antibiotic-induced mutagenesis
• Increase in MIC over time

Correct Answer: Persistent suppression of bacterial growth after antibiotic removal

Q16. Which laboratory method quantifies whether an antibiotic is bactericidal by comparing CFU before and after exposure?

• Time-kill assay
• Disk diffusion
• Gram staining
• PCR amplification

Correct Answer: Time-kill assay

Q17. Which parameter is critical when assessing the safety margin of a new antibiotic?

• Therapeutic index (ratio of toxic dose to effective dose)
• MIC alone without toxicity data
• Disk diffusion zone only
• Color of the drug formulation

Correct Answer: Therapeutic index (ratio of toxic dose to effective dose)

Q18. Which assay is most appropriate to detect heteroresistance in a bacterial population?

• Standard broth microdilution only
• Agar dilution with population analysis profiling
• Simple disk diffusion without interpretation
• Basic Gram stain

Correct Answer: Agar dilution with population analysis profiling

Q19. Which factor can falsely elevate MIC values in in vitro testing?

• Using standardized inoculum
• Presence of high protein binding in test medium
• Strict control of pH and cation concentration
• Incubation at recommended temperature

Correct Answer: Presence of high protein binding in test medium

Q20. What does AUC/MIC ratio primarily predict for many antibiotics?

• Toxicity profile only
• Overall exposure-related efficacy
• Likelihood of allergic reactions
• Disk diffusion zone size

Correct Answer: Overall exposure-related efficacy

Q21. Which phase of clinical trials provides efficacy data in target patient populations?

• Phase I
• Phase II
• Preclinical toxicology
• Investigational New Drug (IND) filing

Correct Answer: Phase II

Q22. Which method is preferred for detecting extended-spectrum beta-lactamase (ESBL) production?

• Disk diffusion using clavulanate combination tests
• Simple MIC reading without beta-lactamase inhibitors
• Gram staining
• ELISA for cytokines

Correct Answer: Disk diffusion using clavulanate combination tests

Q23. In antibiotic drug development, what is the role of ADME studies?

• Assess antimicrobial potency only
• Characterize absorption, distribution, metabolism, and excretion
• Measure bacterial mutation frequency
• Evaluate disk diffusion reproducibility

Correct Answer: Characterize absorption, distribution, metabolism, and excretion

Q24. Which in vitro test helps to determine if two antibiotics are synergistic?

• MIC alone for each drug without combination testing
• Checkerboard assay or time-kill synergy studies
• Serum protein binding assay
• Pharmacovigilance reporting

Correct Answer: Checkerboard assay or time-kill synergy studies

Q25. Which parameter is important for antibiotics cleared primarily by the kidney?

• Hepatic enzyme induction only
• Renal clearance and dose adjustment in renal impairment
• Inability to penetrate bacterial cell wall
• Photosensitivity reactions

Correct Answer: Renal clearance and dose adjustment in renal impairment

Q26. What is the primary objective of post-marketing surveillance for antibiotics?

• Determine in vitro MICs only
• Monitor safety, rare adverse events, and emerging resistance
• Assess disk diffusion technique variability
• Replace clinical trial data

Correct Answer: Monitor safety, rare adverse events, and emerging resistance

Q27. Which characteristic is typical of a narrow-spectrum antibiotic?

• Active against a wide variety of Gram-positive and Gram-negative organisms
• Targeted activity against a limited group of pathogens
• Universal efficacy regardless of resistance
• Only used in topical formulations

Correct Answer: Targeted activity against a limited group of pathogens

Q28. Which test assesses whether an antibiotic is bactericidal by determining 99.9% kill relative to starting inoculum?

• MBC determination
• Gram stain
• Disk diffusion
• Serum protein binding

Correct Answer: MBC determination

Q29. Which factor contributes to the emergence of antibiotic resistance in clinical settings?

• Appropriate narrow-spectrum prescribing only
• Overuse and misuse of antibiotics
• Strict infection control
• High bacterial susceptibility rates

Correct Answer: Overuse and misuse of antibiotics

Q30. What is the significance of protein binding for an antibiotic’s pharmacokinetics?

• Only influences color of formulation
• Determines free, active drug fraction available for activity
• Has no effect on tissue penetration
• Directly measures MIC

Correct Answer: Determines free, active drug fraction available for activity

Q31. Which approach reduces selection pressure and slows resistance development?

• Prolonged low-dose antibiotic use for all infections
• Antibiotic stewardship with targeted therapy
• Empiric broad-spectrum antibiotics for every patient
• Using antibiotics for viral infections

Correct Answer: Antibiotic stewardship with targeted therapy

Q32. Which animal model measurement helps translate PK/PD targets to humans?

• In vitro MIC only
• Free drug exposure (fAUC, fT>MIC) and PK scaling
• Disk diffusion zone diameters in animals
• Visual assessment of behavior only

Correct Answer: Free drug exposure (fAUC, fT>MIC) and PK scaling

Q33. Which cellular target is common for beta-lactam antibiotics?

• Ribosomal 30S subunit
• DNA gyrase
• Peptidoglycan cell wall synthesis (penicillin-binding proteins)
• Folate synthesis enzymes

Correct Answer: Peptidoglycan cell wall synthesis (penicillin-binding proteins)

Q34. What is heteroresistance and why is it important?

• Uniform resistance across a population, not clinically relevant
• Subpopulations within a strain show variable susceptibility, complicating therapy
• Only seen in viral infections
• A laboratory artifact with no clinical implications

Correct Answer: Subpopulations within a strain show variable susceptibility, complicating therapy

Q35. Which in vitro condition must be standardized for reliable MIC testing?

• Inoculum size, incubation time, medium composition, and temperature
• Only the brand of petri dish
• Only the color of the medium
• Time of day when test is run

Correct Answer: Inoculum size, incubation time, medium composition, and temperature

Q36. Which class of antibiotics targets the 50S ribosomal subunit?

• Aminoglycosides
• Macrolides
• Fluoroquinolones
• Beta-lactams

Correct Answer: Macrolides

Q37. What role does molecular diagnostics play in assessing new antibiotics?

• They have no role; only phenotypic tests matter
• Detect specific resistance genes and inform appropriate use
• Replace clinical trials entirely
• Measure drug solubility only

Correct Answer: Detect specific resistance genes and inform appropriate use

Q38. Which outcome measure is critical in phase III trials of a new antibiotic?

• In vitro potency only
• Clinical cure rates and safety in target patient populations
• Only pharmacokinetic parameters in healthy volunteers
• Disk diffusion reproducibility

Correct Answer: Clinical cure rates and safety in target patient populations

Q39. Which phenomenon describes reduced antibiotic susceptibility due to decreased drug entry into Gram-negative bacteria?

• Porin loss or modification leading to decreased permeability
• Ribosomal methylation
• Beta-lactamase inhibition
• Increased target expression only

Correct Answer: Porin loss or modification leading to decreased permeability

Q40. When interpreting susceptibility testing, why is the protein binding of an antibiotic considered?

• Protein-bound drug is inactive; free drug determines effective concentration
• Protein binding increases MIC directly
• It changes bacterial virulence
• It only affects taste of oral formulations

Correct Answer: Protein-bound drug is inactive; free drug determines effective concentration

Q41. Which safety study assesses potential for cardiac QT prolongation of a new antibiotic?

• hERG channel assay and thorough QT studies
• Disk diffusion assay
• MIC determination
• Checkerboard interaction assay

Correct Answer: hERG channel assay and thorough QT studies

Q42. Which mechanism confers resistance to fluoroquinolones?

• Modification of cell wall peptidoglycan
• Mutations in DNA gyrase and topoisomerase IV
• Beta-lactamase production
• Ribosomal protection proteins

Correct Answer: Mutations in DNA gyrase and topoisomerase IV

Q43. In susceptibility testing, why are quality control strains included?

• To calibrate clinical breakpoints without reference
• To ensure test accuracy and consistency across runs
• To replace patient isolates in trials
• They are optional and rarely necessary

Correct Answer: To ensure test accuracy and consistency across runs

Q44. Which characteristic describes a prodrug antibiotic?

• Active in its administered form without metabolism
• Requires metabolic activation to become active
• Always administered topically
• Cannot cross biological membranes

Correct Answer: Requires metabolic activation to become active

Q45. What is the importance of determining the mutant prevention concentration (MPC)?

• It identifies toxic dose limits only
• Helps define dosing to suppress emergence of resistant mutants
• Measures disk diffusion zone extremes
• Replaces MIC in all settings

Correct Answer: Helps define dosing to suppress emergence of resistant mutants

Q46. Which clinical specimen handling practice affects reliability of microbiological assessment?

• Immediate and appropriate transport and storage conditions
• Storing specimens at room temperature indefinitely
• Deliberate contamination to increase growth
• Using expired culture media

Correct Answer: Immediate and appropriate transport and storage conditions

Q47. Which factor is essential when extrapolating animal efficacy data to humans?

• Ignoring PK differences between species
• Accounting for PK/PD relationships and scaling differences
• Using the same dose by mg/kg without adjustment
• Assuming identical immune response in all species

Correct Answer: Accounting for PK/PD relationships and scaling differences

Q48. Which molecular mechanism allows bacteria to pump out antibiotics and confer resistance?

• Enzymatic breakdown
• Efflux pump overexpression
• Target site overproduction only
• Increased membrane porosity

Correct Answer: Efflux pump overexpression

Q49. Which consideration is crucial when developing antibiotics for intracellular pathogens?

• High plasma protein binding only
• Ability to penetrate host cells and reach intracellular compartments
• Avoiding any cellular uptake
• Rely solely on disk diffusion data

Correct Answer: Ability to penetrate host cells and reach intracellular compartments

Q50. Which outcome demonstrates a successful antibiotic development program prior to approval?

• Only low MICs in vitro with no safety data
• Demonstrated clinical efficacy, acceptable safety, and robust PK/PD justification
• High toxicity but excellent in vitro activity
• Approval based solely on animal studies

Correct Answer: Demonstrated clinical efficacy, acceptable safety, and robust PK/PD justification

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