General antibiotic guidelines and surgical prophylaxis MCQs With Answer

Introduction

This collection of MCQs on General antibiotic guidelines and surgical prophylaxis is designed for M.Pharm students preparing for Pharmacotherapeutics II (MPP 202T). The set emphasizes evidence-based perioperative antibiotic strategies, timing and duration of prophylaxis, agent selection according to procedure type and patient factors, redosing criteria, alternatives for beta‑lactam allergy, and principles of antibiotic stewardship such as culture-guided therapy and de‑escalation. Questions focus on pharmacokinetic and pharmacodynamic considerations relevant to surgical prophylaxis, common choice regimens for specific surgeries, and practical decision points encountered in clinical practice. Use these items to test comprehension and apply guidelines to optimize antimicrobial use and minimize resistance and surgical site infections.

Q1. Which statement best describes the ideal timing for administering an intravenous prophylactic antibiotic for most surgical procedures?

• Within 24 hours after skin incision
• Within 120 minutes before incision for all antibiotics
• Within 60 minutes before incision for most agents
• Immediately after wound closure

Correct Answer: Within 60 minutes before incision for most agents

Q2. For patients colonized with MRSA undergoing cardiothoracic or orthopaedic surgery, which perioperative antibiotic strategy is commonly recommended?

• Use ceftriaxone alone
• Add vancomycin to usual beta‑lactam prophylaxis or use vancomycin alone if high MRSA risk
• Use metronidazole alone
• Avoid antibiotics to prevent resistance

Correct Answer: Add vancomycin to usual beta‑lactam prophylaxis or use vancomycin alone if high MRSA risk

Q3. What is the recommended maximum duration for routine postoperative surgical antimicrobial prophylaxis in most clean and clean‑contaminated surgeries?

• Single preoperative dose only; no postoperative doses allowed
• Continue for at least 72 hours postoperatively
• Generally stop within 24 hours after surgery completion
• Continue until drains are removed

Correct Answer: Generally stop within 24 hours after surgery completion

Q4. Which antibiotic is most commonly recommended as first‑line intravenous prophylaxis for many clean procedures, including many orthopaedic and cardiac surgeries?

• Cefazolin
• Gentamicin
• Azithromycin
• Metronidazole

Correct Answer: Cefazolin

Q5. For colorectal surgery (clean‑contaminated), which prophylactic regimen is appropriate to cover both gram‑negative aerobes and anaerobes?

• Cefazolin alone
• Cefazolin plus metronidazole or a single agent like cefoxitin or ertapenem
• Vancomycin alone
• Narrow‑spectrum penicillin alone

Correct Answer: Cefazolin plus metronidazole or a single agent like cefoxitin or ertapenem

Q6. Which principle explains why beta‑lactam antibiotics are commonly administered so that concentrations remain above MIC during surgery?

• They exhibit concentration‑dependent killing
• They act by time‑dependent killing and require time above MIC
• They require once‑daily dosing only
• Their activity is unaffected by time above MIC

Correct Answer: They act by time‑dependent killing and require time above MIC

Q7. When should intraoperative redosing of a prophylactic antibiotic be considered?

• Never; only the initial dose matters
• If procedure duration exceeds two half‑lives of the drug or there is major blood loss (>1500 mL)
• Only if the patient develops an infection intraoperatively
• Only for laparoscopic procedures

Correct Answer: If procedure duration exceeds two half‑lives of the drug or there is major blood loss (>1500 mL)

Q8. For patients with a severe immediate (anaphylactic) penicillin allergy undergoing clean orthopaedic surgery, which prophylactic alternative is commonly recommended?

• Cefazolin with no precautions
• Clindamycin or vancomycin depending on local susceptibility
• Ampicillin
• Ciprofloxacin alone

Correct Answer: Clindamycin or vancomycin depending on local susceptibility

Q9. Which statement about postoperative continuation of antibiotics to prevent surgical site infection is supported by stewardship principles?

• Extended postoperative courses reduce resistance and should be routine
• Continue antibiotics until inflammatory markers normalize
• Limit duration to recommended short course; avoid routine extended prophylaxis
• Give daily oral antibiotics for one week for every surgery

Correct Answer: Limit duration to recommended short course; avoid routine extended prophylaxis

Q10. Which monitoring or adjustment is most important when using aminoglycosides for perioperative prophylaxis in high‑risk patients?

• No monitoring is required for aminoglycosides
• Therapeutic drug monitoring (peak/trough) to avoid toxicity and adjust dosing
• Only monitor liver enzymes
• Reduce dose by half in all patients regardless of renal function

Correct Answer: Therapeutic drug monitoring (peak/trough) to avoid toxicity and adjust dosing

Q11. Which factor is least important when selecting an antibiotic for surgical prophylaxis?

• Expected microbial flora at surgical site
• Pharmacokinetics and tissue penetration
• Cost of the antibiotic as the sole criterion
• Patient allergies and local resistance patterns

Correct Answer: Cost of the antibiotic as the sole criterion

Q12. In what scenario is postoperative therapeutic antibiotics indicated rather than prophylaxis?

• Uncomplicated clean procedure without contamination
• When there is documented infection at the surgical site or positive intraoperative cultures
• Routine implant surgery with no signs of infection
• For every patient with a drain in place

Correct Answer: When there is documented infection at the surgical site or positive intraoperative cultures

Q13. Which agent is typically used for prophylaxis in procedures with significant anaerobic risk (e.g., colorectal) if cefoxitin is unavailable?

• Amoxicillin alone
• Cefazolin plus metronidazole
• Trimethoprim alone
• Vancomycin alone

Correct Answer: Cefazolin plus metronidazole

Q14. What is the primary rationale for de‑escalation of empirical perioperative antibiotics when culture results are available?

• To increase antibiotic spectrum and prevent resistance
• To switch to broader agents once culture is positive
• To minimize toxicity, cost and selection pressure by using the narrowest effective agent
• To prolong therapy to ensure eradication

Correct Answer: To minimize toxicity, cost and selection pressure by using the narrowest effective agent

Q15. Which guideline‑consistent approach applies to prophylaxis for clean urologic procedures without prosthetic implantation?

• No antibiotic prophylaxis is ever needed
• A single preoperative dose targeted to urinary pathogens is usually appropriate
• Prolonged oral antibiotics for 5–7 days postoperatively
• Use vancomycin prophylactically for all urologic cases

Correct Answer: A single preoperative dose targeted to urinary pathogens is usually appropriate

Q16. Which statement reflects the role of local antibiograms in choosing perioperative prophylaxis?

• Local resistance patterns should be ignored for prophylaxis
• Local antibiograms help tailor agent selection to prevalent organisms and resistance
• National guidelines override all local data and should be applied uniformly
• Antibiograms are only useful for outpatient infections

Correct Answer: Local antibiograms help tailor agent selection to prevalent organisms and resistance

Q17. For patients receiving vancomycin for prophylaxis, what is an important practical consideration related to timing?

• Vancomycin can be infused rapidly immediately before incision
• Start vancomycin infusion early, often within 120 minutes before incision, because it requires slow infusion
• Give vancomycin only after surgery
• Timing for vancomycin is not relevant to efficacy

Correct Answer: Start vancomycin infusion early, often within 120 minutes before incision, because it requires slow infusion

Q18. Which of the following is NOT a recognized indication for extended postoperative antibiotic prophylaxis?

• Established postoperative wound infection
• Routine use after clean, uncomplicated procedures
• Documented contaminated surgery requiring therapeutic therapy
• Persistent bacteremia identified postoperatively

Correct Answer: Routine use after clean, uncomplicated procedures

Q19. In antibiotic stewardship metrics for surgical prophylaxis, which measure is most commonly tracked?

• Percentage of patients receiving prophylaxis within recommended timing window
• Number of surgical staff trained in suturing
• Patient satisfaction scores only
• Hospital cafeteria food quality

Correct Answer: Percentage of patients receiving prophylaxis within recommended timing window

Q20. Which statement best describes the use of topical or local antibiotics (e.g., antibiotic irrigation) as a substitute for systemic prophylaxis?

• Topical antibiotics reliably replace systemic IV prophylaxis in all surgeries
• Evidence is limited; topical agents may be adjunctive but do not generally replace appropriately timed systemic prophylaxis
• Topical antibiotics always increase systemic toxicity and are contraindicated
• Topical use prolongs prophylaxis and is preferred over single IV dosing

Correct Answer: Evidence is limited; topical agents may be adjunctive but do not generally replace appropriately timed systemic prophylaxis

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