Antiseptics – evaluation MCQs With Answer

Antiseptics – evaluation MCQs With Answer

This concise, SEO-friendly introduction helps B. Pharm students master antiseptic evaluation through focused MCQs. Covering antiseptic agents, mechanisms of action, spectrum of activity, testing methods (phenol coefficient, suspension tests, MIC/MBC), factors affecting efficacy (organic load, contact time, concentration, pH), and regulatory standards, these questions reinforce practical and theoretical concepts. Ideal for exam prep and clinical formulation understanding, the content emphasizes in vitro/in vivo evaluation, neutralizers, substantivity, biofilm activity, and common antiseptics like chlorhexidine, povidone-iodine, alcohols, quats, and hydrogen peroxide. Clear, targeted practice improves decision-making for antiseptic selection and quality control. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which test is classically used to compare the activity of an antiseptic with phenol under standardized conditions?

• Minimum Inhibitory Concentration (MIC) test
• Phenol coefficient test
• Agar diffusion test
• Carrier test

Correct Answer: Phenol coefficient test

Q2. In antiseptic evaluation, what does MIC measure?

• The lowest antiseptic concentration that kills 99.9% of organisms
• The time required to achieve a 3 log reduction
• The lowest concentration that inhibits visible microbial growth
• The residual activity left on skin after application

Correct Answer: The lowest concentration that inhibits visible microbial growth

Q3. Which factor most commonly reduces the apparent activity of an antiseptic in laboratory tests?

• Low temperature
• Presence of organic matter
• High pH stability
• Use of distilled water as diluent

Correct Answer: Presence of organic matter

Q4. Which antiseptic is known for rapid bactericidal action but poor residual activity?

• Chlorhexidine gluconate
• Povidone-iodine
• 70% Isopropyl alcohol
• Benzalkonium chloride

Correct Answer: 70% Isopropyl alcohol

Q5. Which test assesses antiseptic efficacy on contaminated surfaces or materials rather than in suspension?

• Suspension test
• Agar dilution test
• Carrier test
• MIC determination

Correct Answer: Carrier test

Q6. Substantivity of an antiseptic refers to:

• Its ability to penetrate biofilms
• Residual activity after application to skin or mucosa
• Its resistance to inactivation by organic matter
• Speed of initial kill within 10 seconds

Correct Answer: Residual activity after application to skin or mucosa

Q7. Which antiseptic is a biguanide widely used in surgical scrubs for long-lasting activity?

• Triclosan
• Chlorhexidine
• Povidone-iodine
• Phenol

Correct Answer: Chlorhexidine

Q8. The term “log reduction” in antiseptic testing indicates:

• The logarithm of the antiseptic concentration
• The fold decrease in microbial count expressed logarithmically
• Time in minutes for complete elimination of microbes
• The pH change caused by the antiseptic

Correct Answer: The fold decrease in microbial count expressed logarithmically

Q9. Which method is suitable for testing antiseptic effect on enveloped versus non-enveloped viruses?

• Phenol coefficient test
• Cell culture infectivity assays
• Disk diffusion on agar
• Gram staining

Correct Answer: Cell culture infectivity assays

Q10. A neutralizer in antiseptic testing is used to:

• Enhance antiseptic activity during assay
• Stop antiseptic action at defined contact time
• Reduce microbial growth on control plates
• Increase antiseptic penetration into tissues

Correct Answer: Stop antiseptic action at defined contact time

Q11. Phenolic antiseptics primarily exert antimicrobial action by:

• Disrupting cell membranes and denaturing proteins
• Interfering with DNA replication
• Inhibiting cell wall synthesis
• Acting as competitive enzyme inhibitors

Correct Answer: Disrupting cell membranes and denaturing proteins

Q12. Which antiseptic is commonly formulated as an iodophor with sustained iodine release?

• Chloroxylenol
• Povidone-iodine
• Hydrogen peroxide
• Benzalkonium chloride

Correct Answer: Povidone-iodine

Q13. In antiseptic evaluation, the suspension test primarily measures:

• Surface decontamination efficacy
• Activity in presence of organic load
• Kill rate of microorganisms in a liquid medium
• Residual activity on skin

Correct Answer: Kill rate of microorganisms in a liquid medium

Q14. Which antiseptic shows good activity against Gram-positive bacteria and has limited sporicidal action?

• Alcohols
• Hydrogen peroxide
• Formaldehyde
• Peracetic acid

Correct Answer: Alcohols

Q15. The MBC is defined as:

• The lowest concentration preventing visible growth
• The concentration causing 50% reduction in growth
• The lowest concentration that kills a specified proportion of the inoculum
• The time to achieve microbial inhibition

Correct Answer: The lowest concentration that kills a specified proportion of the inoculum

Q16. Which parameter is most important when selecting an antiseptic for mucous membrane application?

• High phenol coefficient
• Low tissue irritation and toxicity
• Maximum residual activity on skin
• Ability to form foam

Correct Answer: Low tissue irritation and toxicity

Q17. Quaternary ammonium compounds (QACs) like benzalkonium chloride are especially effective against:

• Spores and non-enveloped viruses
• Gram-negative bacteria and enveloped viruses
• Prions
• Mycobacteria

Correct Answer: Gram-negative bacteria and enveloped viruses

Q18. Which antiseptic is an oxidizing agent that can be used for wound irrigation and has bubbling action?

• Chlorhexidine
• Hydrogen peroxide
• Triclosan
• Boric acid

Correct Answer: Hydrogen peroxide

Q19. The “in-use” test for antiseptics evaluates:

• Laboratory potency under ideal conditions
• Field performance of formulation during routine use
• Compatibility with packaging materials only
• Animal toxicity of the antiseptic

Correct Answer: Field performance of formulation during routine use

Q20. Why are neutralizer validation controls necessary in antiseptic assays?

• To confirm neutralizer does not support microbial growth
• To verify the neutralizer effectively stops antiseptic action without toxicity
• To increase antiseptic potency in the test
• To standardize inoculum size across assays

Correct Answer: To verify the neutralizer effectively stops antiseptic action without toxicity

Q21. Which antiseptic is known for strong sporicidal and broad-spectrum activity used in high-level disinfection?

• Isopropyl alcohol 70%
• Glutaraldehyde
• Chlorhexidine
• Benzalkonium chloride

Correct Answer: Glutaraldehyde

Q22. Which standardized body publishes methods like EN and ASTM for antiseptic testing?

• FDA only
• European Committee for Standardization (CEN) and ASTM International
• WHO exclusively
• International Olympic Committee

Correct Answer: European Committee for Standardization (CEN) and ASTM International

Q23. Which property makes alcohols poor antiseptics for treating deep wounds?

• Rapid evaporation and lack of residual activity
• High substantivity on skin
• Ability to denature proteins
• Compatibility with mucous membranes

Correct Answer: Rapid evaporation and lack of residual activity

Q24. Triclosan’s main mode of action at low concentrations is:

• Generalized membrane disruption
• Inhibition of enoyl-acyl carrier protein reductase affecting fatty acid synthesis
• Oxidative damage to DNA
• Alkylation of thiol groups in proteins

Correct Answer: Inhibition of enoyl-acyl carrier protein reductase affecting fatty acid synthesis

Q25. Which parameter is used to express antiseptic potency in phenol coefficient testing?

• Ratio of kill time of test antiseptic to phenol
• Absolute concentration in mg/mL
• pH stability index
• Viscosity compared to water

Correct Answer: Ratio of kill time of test antiseptic to phenol

Q26. Biofilm presence affects antiseptic efficacy primarily because biofilms:

• Increase pH and deactivate antiseptics chemically
• Create a protective matrix reducing antiseptic penetration
• Convert antiseptics into more active metabolites
• Enhance growth rate making cells more susceptible

Correct Answer: Create a protective matrix reducing antiseptic penetration

Q27. For hand antisepsis in hospital settings, which combination is often preferred for both immediate and persistent effect?

• 70% ethanol alone
• Chlorhexidine with an alcohol base
• Povidone-iodine aqueous solution only
• Benzalkonium chloride rinse only

Correct Answer: Chlorhexidine with an alcohol base

Q28. Which antiseptic is contraindicated for use in neonates due to iodine absorption concerns?

• Povidone-iodine
• 70% Isopropyl alcohol
• Chlorhexidine gluconate in low concentration
• Benzalkonium chloride

Correct Answer: Povidone-iodine

Q29. Which analytical endpoint demonstrates bactericidal rather than bacteriostatic action?

• MIC value only
• Zone of inhibition size
• MBC value
• Optical density decrease in growth curve

Correct Answer: MBC value

Q30. High organic load in antiseptic testing mimics which real-world condition?

• Sterile laboratory water
• Clean, dry skin
• Blood, pus, or body fluids on instruments
• High ambient temperature environments

Correct Answer: Blood, pus, or body fluids on instruments

Q31. Which antiseptic is particularly effective against Clostridioides difficile spores when used as per guidelines?

• 70% ethanol
• Sodium hypochlorite (bleach)
• Benzalkonium chloride
• Chlorhexidine

Correct Answer: Sodium hypochlorite (bleach)

Q32. Which antiseptic evaluation method yields quantitative log10 reduction data after contact time?

• Disk diffusion assay
• Time-kill suspension assay
• Gram staining
• pH titration

Correct Answer: Time-kill suspension assay

Q33. Which antiseptic is a halogen-based oxidizer effective against bacteria, viruses, and fungi and used in wound care?

• Peracetic acid
• Silver sulfadiazine
• Povidone-iodine
• Triclosan

Correct Answer: Povidone-iodine

Q34. Antiseptic resistance mechanisms can include which of the following?

• Efflux pumps, membrane modification, and enzymatic degradation
• Increased sensitivity to oxidative stress
• Complete loss of cell wall
• Conversion to eukaryotic cells

Correct Answer: Efflux pumps, membrane modification, and enzymatic degradation

Q35. In antiseptic formulation, which excipient commonly increases substantivity of chlorhexidine?

• High ethanol content above 90%
• Use of polyvinylpyrrolidone carrier
• Inclusion of a suitable surfactant or emollient
• Adding strong oxidizers like hydrogen peroxide

Correct Answer: Inclusion of a suitable surfactant or emollient

Q36. Which antiseptic is least appropriate for use on open, deep surgical wounds due to tissue toxicity?

• Normal saline irrigation
• Hydrogen peroxide 3%
• Povidone-iodine diluted as recommended
• Isotonic chlorhexidine rinses designed for wounds

Correct Answer: Hydrogen peroxide 3%

Q37. Which measure describes the time required for a 90% reduction (1 log) in microbial population at a given antiseptic concentration?

• MIC
• MBC
• D-value (decimal reduction time)
• Phenol coefficient

Correct Answer: D-value (decimal reduction time)

Q38. Which antiseptic class is most likely to be inactivated by anionic detergents?

• Alcohols
• Quaternary ammonium compounds
• Peroxygens
• Biguanides

Correct Answer: Quaternary ammonium compounds

Q39. For regulatory documentation of antiseptic efficacy, which outcome is most persuasive?

• Qualitative color change of solution
• Peer-reviewed, standardized quantitative log10 reduction data
• User testimonials
• Manufacturer’s unpublished notes

Correct Answer: Peer-reviewed, standardized quantitative log10 reduction data

Q40. Which antiseptic is commonly used as a preservative in topical formulations and shows phenolic characteristics?

• Parabens
• Chloroxylenol (PCMX)
• Hydrogen peroxide
• Silver nitrate

Correct Answer: Chloroxylenol (PCMX)

Q41. When evaluating antiseptic activity against biofilms in vitro, which assay adaptation is most relevant?

• Using planktonic cultures only
• Growing microbes on surfaces to form mature biofilms before treatment
• Measuring pH changes only
• Excluding organic load from tests

Correct Answer: Growing microbes on surfaces to form mature biofilms before treatment

Q42. Which antiseptic mechanism primarily involves oxidation of cellular components?

• Alcohol denaturation
• Peroxygen compounds like peracetic acid
• Quaternary ammonium membrane solubilization
• Biguanide protein precipitation

Correct Answer: Peroxygen compounds like peracetic acid

Q43. In designing an antiseptic efficacy study, why include multiple microbial species including gram-positive, gram-negative, fungal and viral representatives?

• To increase experiment complexity only
• Because antiseptics have uniform activity across all microbes
• To evaluate broad-spectrum activity and spectrum limitations
• Because regulatory agencies require viruses only

Correct Answer: To evaluate broad-spectrum activity and spectrum limitations

Q44. Which antiseptic is commonly combined with alcohol in hand rubs to enhance both immediate kill and residual activity?

• Triclosan
• Chlorhexidine gluconate
• Sodium hypochlorite
• Formaldehyde

Correct Answer: Chlorhexidine gluconate

Q45. Which laboratory control demonstrates that the initial microbial inoculum size was correct in an antiseptic assay?

• Neutralizer toxicity control
• Growth control (untreated inoculum)
• Negative sterility control
• Phenol standard curve

Correct Answer: Growth control (untreated inoculum)

Q46. Which antiseptic is effective as a topical agent due to release of silver ions that disrupt microbial enzymes and membranes?

• Silver sulfadiazine
• Povidone-iodine
• 70% ethanol
• Quaternary ammonium compounds

Correct Answer: Silver sulfadiazine

Q47. For antiseptic efficacy against mycobacteria, which characteristic is most relevant?

• Ability to solubilize lipids in mycobacterial cell envelope
• High buffering capacity
• Strong surfactant foaming
• Low molecular weight

Correct Answer: Ability to solubilize lipids in mycobacterial cell envelope

Q48. Which antiseptic is unsuitable for use in presence of heavy organic matter because it is rapidly inactivated by proteins?

• Hypochlorite (bleach)
• 70% ethanol
• Phenolic compounds
• Iodophors like povidone-iodine

Correct Answer: Hypochlorite (bleach)

Q49. During antiseptic formulation testing, compatibility with packaging is assessed primarily to ensure:

• Attractive label appearance
• No chemical interaction that reduces efficacy or causes leachables
• Faster evaporation from container
• Higher manufacturing yield

Correct Answer: No chemical interaction that reduces efficacy or causes leachables

Q50. Which outcome best indicates an antiseptic has both rapid kill and sustained residual activity on skin?

• High phenol coefficient only
• Large zone of inhibition in disk diffusion
• Initial high log10 reduction in time-kill assay plus persistent reduction in simulated skin transfer assays
• Low MIC against a single strain only

Correct Answer: Initial high log10 reduction in time-kill assay plus persistent reduction in simulated skin transfer assays

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