A 54-year-old man ventilated in a Mumbai ICU has bacteraemia with Klebsiella pneumoniae resistant to meropenem. Meropenem's zone of inhibition increases markedly with EDTA, the isolate is resistant to ceftazidime-avibactam, and aztreonam alone tests resistant. Which regimen is most likely to be effective?

Ceftazidime-avibactam plus aztreonam

High-dose extended-infusion meropenem

A 32-year-old lab technician in Bhopal has a needle-stick injury from an HBsAg-positive patient's sample. She received three doses of hepatitis B vaccine years ago but her antibody response was never tested. Her anti-HBs today is 4 mIU/mL. What should be done for hepatitis B?

One dose of HBIG plus a vaccine dose

No action as she is fully vaccinated

Two doses of HBIG one month apart

A 72-year-old woman in a medicine ward in Pune develops profuse diarrhoea on day 6 of IV ceftriaxone, and her stool is positive for Clostridioides difficile toxin. How should staff clean their hands after caring for her?

Wearing gloves without hand hygiene

Hospital infection control and antimicrobial resistance

26 NEET-PG practice questions on Hospital infection control and antimicrobial resistance, part of Microbiology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A 54-year-old man ventilated in a Mumbai ICU has bacteraemia with Klebsiella pneumoniae resistant to meropenem. Meropenem's zone of inhibition increases markedly with EDTA, the isolate is resistant to ceftazidime-avibactam, and aztreonam alone tests resistant. Which regimen is most likely to be effective?
1. APiperacillin-tazobactam
2. BHigh-dose extended-infusion meropenem
3. CCeftazidime-avibactam alone
4. DCeftazidime-avibactam plus aztreonam
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Answer: D · Ceftazidime-avibactam plus aztreonam
Enhancement of the meropenem zone with EDTA, which chelates zinc, shows a metallo-beta-lactamase such as NDM, common in India. Metallo-enzymes hydrolyse all beta-lactams except aztreonam and are not inhibited by avibactam, so ceftazidime-avibactam fails. Aztreonam alone also fails here because co-produced ESBLs or AmpC enzymes hydrolyse it; adding avibactam protects aztreonam from these enzymes, so the combination works. Results like these should be reported early so that contact precautions can begin.
- A: Piperacillin-tazobactam is hydrolysed by both NDM and ESBLs.
- B: Meropenem is hydrolysed by NDM regardless of dose or infusion time.
- C: Avibactam does not inhibit metallo-beta-lactamases, as the test shows.
Question 2 · Hard
A 32-year-old lab technician in Bhopal has a needle-stick injury from an HBsAg-positive patient's sample. She received three doses of hepatitis B vaccine years ago but her antibody response was never tested. Her anti-HBs today is 4 mIU/mL. What should be done for hepatitis B?
1. ANo action as she is fully vaccinated
2. BA single vaccine booster only
3. COne dose of HBIG plus a vaccine dose
4. DTwo doses of HBIG one month apart
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Answer: C · One dose of HBIG plus a vaccine dose
When a vaccinated worker's response is unknown, anti-HBs is tested at once after the exposure. A level of 10 mIU/mL or more means no treatment; a level below 10, as here, means she may not be protected, so she is given one dose of HBIG together with a vaccine dose, and her revaccination is completed with anti-HBs rechecked later. HBIG should be given as soon as possible, ideally within 24 hours. Two doses of HBIG are kept for known non-responders who have completed two vaccine series.
- A: Vaccination without proof of response does not guarantee protection.
- B: A booster alone does not give immediate passive protection.
- D: Two doses of HBIG are for known non-responders after two series.
Question 3 · Easy
An infection control nurse in a district hospital in Thrissur trains new interns on the WHO technique for hand rubbing with an alcohol-based formulation. For how long should the whole procedure take?
1. A20-30 seconds
2. B40-60 seconds
3. C90-120 seconds
4. D10-15 seconds
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Answer: A · 20-30 seconds
By the WHO guidelines, hand rubbing with an alcohol-based rub covering all surfaces of the hands should take 20-30 seconds, until the hands are dry. Hand washing with soap and water takes longer, about 40-60 seconds. Alcohol rub is preferred for routine hand hygiene when hands are not visibly soiled, because it is faster and better tolerated. Visibly dirty hands, and exposure to spore-formers, need soap and water.
- B: 40-60 seconds is the duration for washing with soap and water.
- C: Ninety seconds or more is far longer than a routine hand rub needs.
- D: Ten to fifteen seconds is too short to cover all hand surfaces.
Question 4 · Medium
A 66-year-old woman in a Jaipur ICU has urosepsis with a BP of 84/50 mmHg. Klebsiella pneumoniae from blood is resistant to ceftriaxone and ceftazidime but sensitive to cefoxitin, and the inhibition zone around ceftazidime increases by more than 5 mm when clavulanic acid is added. Which antibiotic is most appropriate?
1. AMeropenem
2. BAmoxicillin-clavulanate
3. CCeftriaxone in high dose
4. DCefoxitin
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Answer: A · Meropenem
Resistance to third-generation cephalosporins with sensitivity to cefoxitin and a zone increase of 5 mm or more with clavulanic acid confirms an extended-spectrum beta-lactamase (ESBL). ESBLs hydrolyse penicillins and third-generation cephalosporins but not cephamycins or carbapenems, and are inhibited by clavulanate. A carbapenem such as meropenem is the drug of choice for serious ESBL infections such as bacteraemia with shock. Using the cephalosporin in higher doses does not overcome ESBL resistance.
- B: Oral amoxicillin-clavulanate is not adequate for septic shock with bacteraemia.
- C: Higher doses do not overcome ESBL hydrolysis of ceftriaxone.
- D: Cefoxitin is not a reliable treatment for serious ESBL bacteraemia, even if it tests sensitive.
Question 5 · Easy
A 72-year-old woman in a medicine ward in Pune develops profuse diarrhoea on day 6 of IV ceftriaxone, and her stool is positive for Clostridioides difficile toxin. How should staff clean their hands after caring for her?
1. ASoap and water washing
2. BWearing gloves without hand hygiene
3. CAlcohol-based hand rub
4. DChlorhexidine-alcohol hand rub
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Answer: A · Soap and water washing
Clostridioides difficile forms spores, which alcohol does not kill, so alcohol-based hand rubs cannot be relied on after contact with such patients. Washing with soap and running water removes the spores mechanically. Contact precautions with gloves and gowns are added, and surfaces are cleaned with a sporicidal agent such as hypochlorite. Gloves never replace hand hygiene after their removal.
- B: Hands are contaminated when gloves are removed and must still be washed.
- C: Alcohol does not kill C. difficile spores.
- D: Adding chlorhexidine to alcohol does not make the rub sporicidal.
Question 6 · Medium
A 45-year-old man is admitted in Kochi with fever for 2 days and no intravascular device or prosthesis. Two blood culture sets were drawn from separate veins. On day 3, one bottle of one set grows coagulase-negative staphylococci; the other set remains sterile. How should this result be interpreted?
1. ATrue bacteraemia needing vancomycin
2. BInfective endocarditis until proven otherwise
3. CDefinite catheter-related bloodstream infection
4. DProbable contamination from skin flora
Answer and explanation in LearnFree account
Question 7 · Medium
At an orientation session for interns in a medical college in Nagpur, a microbiologist discusses specimen handling: 1. CSF from suspected meningococcal meningitis may be refrigerated if transport is delayed. 2. Urine for culture should be refrigerated at 4 °C if it cannot reach the laboratory within 2 hours. 3. Inoculated blood culture bottles should be refrigerated overnight. 4. Sputum for AFB microscopy may be refrigerated if it cannot be sent the same day. Which statements are correct?
1. A1 and 2 only
2. B2 and 4 only
3. C2, 3 and 4 only
4. D1, 2, 3 and 4
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Question 8 · Medium
A 58-year-old diabetic man in a surgical ward in Delhi has a wound infection. The isolate is Staphylococcus aureus resistant to cefoxitin on disc diffusion. Which mechanism explains its resistance to all beta-lactams?
1. AAltered penicillin-binding protein PBP2a
2. BActive efflux of the antibiotic
3. CProduction of a plasmid penicillinase
4. DLoss of outer membrane porins
Answer and explanation in LearnFree account
Question 9 · Medium
A 30-year-old staff nurse in Hyderabad sustains a needle-stick injury while recapping a needle used on a patient with chronic hepatitis C (HCV RNA positive). Her baseline anti-HCV is negative. What is the recommended approach for hepatitis C?
1. AStart a direct-acting antiviral at once as prophylaxis
2. BGive immunoglobulin within 72 hours
3. CGive hepatitis C vaccine at once
4. DFollow-up testing, with treatment if infection occurs
Answer and explanation in LearnFree account
Question 10 · Medium
Before elective cardiac surgery in a hospital in Bengaluru, a 64-year-old man's nasal swab grows MRSA. He has no active infection. What is the most appropriate step to reduce the risk of a post-operative MRSA infection?
1. AIV linezolid for 7 days before surgery
2. BOral vancomycin for 5 days
3. CNasal mupirocin with chlorhexidine body washes
4. DPostpone surgery until three nasal swabs are negative
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Question 11 · Medium
The infection control committee of a hospital in Lucknow audits central line insertion in its ICU and lists four practices: 1. Skin preparation with chlorhexidine in alcohol. 2. The femoral vein is the preferred site in adults. 3. Maximal sterile barrier precautions during insertion. 4. Routine replacement of central lines every 7 days. Which practices reduce central line-associated bloodstream infection?
1. A1 and 3 only
2. B1 and 4 only
3. C1, 3 and 4 only
4. D3 and 4 only
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Question 12 · Medium
A 26-year-old house surgeon in Chandigarh pricks her finger with a needle used on a patient who is HBsAg-positive. She completed three doses of hepatitis B vaccine as a student, and her anti-HBs level checked after the course was 120 mIU/mL. What should be done for hepatitis B?
1. AGive HBIG and a vaccine booster dose
2. BRepeat the full three-dose vaccine series
3. CGive HBIG alone within 24 hours
4. DNo hepatitis B prophylaxis is needed
Answer and explanation in LearnFree account
Question 13 · Medium
A 50-year-old man in a renal transplant unit in Chennai has a urinary infection with Enterococcus faecium resistant to vancomycin and teicoplanin (VanA phenotype). What change in the bacterial cell wall causes this resistance?
1. AD-Ala-D-Ala replaced by D-Ala-D-Lac
2. BProduction of a vancomycin-hydrolysing enzyme
3. CAltered 30S ribosomal subunit
4. DMutation in DNA gyrase
Answer and explanation in LearnFree account
Question 14 · Easy
Immediately after a needle-stick injury from a used IV cannula in the ward, what should the nurse do first?
1. AScrub the site with povidone-iodine and a brush
2. BSqueeze the wound hard to make it bleed
3. CSoak the finger in sodium hypochlorite
4. DWash the site with soap and running water
Answer and explanation in LearnFree account
Question 15 · Medium
Disc diffusion of a Klebsiella pneumoniae isolate from urine: ceftazidime 30 µg, zone 12 mm; ceftazidime-clavulanate 30/10 µg, zone 21 mm; cefotaxime 30 µg, zone 14 mm; cefotaxime-clavulanate 30/10 µg, zone 23 mm; meropenem, zone 28 mm (susceptible). What does this pattern show?
1. ALoss of outer membrane porins alone
2. BCarbapenemase production
3. CPlasmid-mediated AmpC beta-lactamase
4. DExtended-spectrum beta-lactamase production
Answer and explanation in LearnFree account
Question 16 · Medium
Exposure report: a few drops of blood from an HIV-positive patient splashed onto the intact skin of a ward attendant's forearm while she changed bed linen. There were no cuts, abrasions or dermatitis, and she washed the area with soap and water within a minute. No mucous membrane was involved. What should be done about HIV PEP?
1. AGive PEP and repeat HIV tests for 6 months
2. BStart a two-drug PEP regimen for 28 days
3. CNo PEP is needed; reassure and counsel
4. DStart a three-drug PEP regimen for 28 days
Answer and explanation in LearnFree account
Question 17 · Easy
After emptying a patient's urinary catheter bag while wearing gloves, a ward nurse takes off her gloves. What should she do next?
1. APerform hand hygiene at once
2. BPut on fresh gloves over unwashed hands
3. CGo to the next patient, as gloves were worn
4. DWash her hands at the end of the shift
Answer and explanation in LearnFree account
Question 18 · Medium
A meropenem-resistant Klebsiella pneumoniae grows from an ICU patient's blood. Which test shows whether a carbapenemase causes the resistance?
1. AD-test with erythromycin and clindamycin
2. BCefoxitin disc screening test
3. CModified carbapenem inactivation method
4. DDouble-disc synergy test
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Question 19 · Hard
Urine culture of a non-pregnant woman with 2 days of dysuria and frequency, no fever and no flank pain, grows more than 10^5 CFU/mL Escherichia coli. It is an ESBL producer, resistant to ciprofloxacin, cefixime and co-trimoxazole, and susceptible to nitrofurantoin, fosfomycin and meropenem. Her creatinine is 0.8 mg/dL. She is well and at home. What is the best treatment?
1. AIV meropenem
2. BOral amoxicillin-clavulanate
3. CIV piperacillin-tazobactam
4. DOral nitrofurantoin
Answer and explanation in LearnFree account
Question 20 · Medium
Staphylococcus aureus grows from a post-operative wound swab in the orthopaedic ward. On CLSI disc diffusion, the cefoxitin 30 µg zone is 18 mm (susceptible 22 mm or more; resistant 21 mm or less). Penicillin is resistant and vancomycin MIC is 1 µg/mL. What does the cefoxitin result indicate?
1. AVancomycin-intermediate S. aureus
2. BMethicillin resistance through mecA (MRSA)
3. CPenicillinase production only
4. DInducible clindamycin resistance
Answer and explanation in LearnFree account
Question 21 · Hard
A penicillin-allergic patient with a large thigh abscess grows Staphylococcus aureus. The routine report says erythromycin resistant and clindamycin susceptible, and the physician plans oral clindamycin after drainage. The microbiologist then places erythromycin and clindamycin discs 15 mm apart; the clindamycin zone is flattened on the side facing the erythromycin disc, giving a D shape. Cefoxitin zone is 25 mm (susceptible 22 mm or more). The abscess is in a diabetic man whose HbA1c is 8.4%, and he has had two boils in the past year. What should be reported?
1. AMethicillin-resistant S. aureus
2. BEfflux-mediated macrolide resistance only
3. CClindamycin susceptible, as on the first report
4. DClindamycin resistant: inducible MLSB resistance
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Question 22 · Medium
In a district hospital at 6 pm, a junior resident reports a deep needle-stick sustained 30 hours ago while drawing blood from a patient known to be HIV-positive; she delayed reporting because of a busy night shift. She has had no previous HIV test this year, and her baseline HIV test is sent now. She is not pregnant, is fully vaccinated against hepatitis B and has a protective anti-HBs titre. The source patient has been on ART for 2 years. She asks whether it is now too late to take any medicine. What is the correct advice about PEP?
1. AGive a single dose of the PEP drugs now
2. BStart PEP only if her HIV test is positive
3. CPEP is no longer useful after 24 hours
4. DStart PEP now and continue for 28 days
Answer and explanation in LearnFree account
Question 23 · Medium
Before an NABH audit of a medical college laboratory, the microbiologist checks four rules for specimen handling: 1. CSF for suspected bacterial meningitis is refrigerated if it cannot be processed at once. 2. Urine for culture that cannot be processed within 2 hours is kept at 4°C. 3. Inoculated blood culture bottles awaiting loading are kept at room temperature, not refrigerated. 4. Sputum for AFB is best collected in the early morning. Which rules are correct?
1. A1, 2 and 3 only
2. B2, 3 and 4 only
3. C1, 2, 3 and 4
4. D1 and 4 only
Answer and explanation in LearnFree account
Question 24 · Hard
The infection control committee of a tertiary hospital reviews central line-associated bloodstream infections (CLABSI) for the last quarter, as shown. The intensive care unit reported the largest number of infections, so the administrator wants to start the bundle audit there. The committee decides to rank units by rate per 1,000 central-line days instead. Which unit should be audited first, and with what rate?
Figure: MedExams
1. AMedical ward, 2.0
2. BOncology ward, 5.0
3. CSurgical ward, 4.0
4. DIntensive care unit, 2.5
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Question 25 · Easy
A staff nurse is about to enter the isolation room of a man with sputum smear-positive pulmonary tuberculosis. She will wear the respirator shown. Which step must she do every time she puts it on?
Figure: Photo: Debora Cartagena, Public domain, via Wikimedia Commons
1. APerform a user seal check for leaks
2. BWear it inside out so the clean side faces her
3. CWear it over a surgical mask for added protection
4. DRub alcohol on the outer surface before entering
Answer and explanation in LearnFree account

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Hospital infection control and antimicrobial resistance

A 32-year-old lab technician in Bhopal has a needle-stick injury from an HBsAg-positive patient's sample. She received three doses of hepatitis B vaccine years ago but her antibody response was never tested. Her anti-HBs today is 4 mIU/mL. What should be done for hepatitis B?

An infection control nurse in a district hospital in Thrissur trains new interns on the WHO technique for hand rubbing with an alcohol-based formulation. For how long should the whole procedure take?

A 72-year-old woman in a medicine ward in Pune develops profuse diarrhoea on day 6 of IV ceftriaxone, and her stool is positive for Clostridioides difficile toxin. How should staff clean their hands after caring for her?

A 58-year-old diabetic man in a surgical ward in Delhi has a wound infection. The isolate is Staphylococcus aureus resistant to cefoxitin on disc diffusion. Which mechanism explains its resistance to all beta-lactams?

A 30-year-old staff nurse in Hyderabad sustains a needle-stick injury while recapping a needle used on a patient with chronic hepatitis C (HCV RNA positive). Her baseline anti-HCV is negative. What is the recommended approach for hepatitis C?

Before elective cardiac surgery in a hospital in Bengaluru, a 64-year-old man's nasal swab grows MRSA. He has no active infection. What is the most appropriate step to reduce the risk of a post-operative MRSA infection?

A 26-year-old house surgeon in Chandigarh pricks her finger with a needle used on a patient who is HBsAg-positive. She completed three doses of hepatitis B vaccine as a student, and her anti-HBs level checked after the course was 120 mIU/mL. What should be done for hepatitis B?

A 50-year-old man in a renal transplant unit in Chennai has a urinary infection with Enterococcus faecium resistant to vancomycin and teicoplanin (VanA phenotype). What change in the bacterial cell wall causes this resistance?

Immediately after a needle-stick injury from a used IV cannula in the ward, what should the nurse do first?

Disc diffusion of a Klebsiella pneumoniae isolate from urine: ceftazidime 30 µg, zone 12 mm; ceftazidime-clavulanate 30/10 µg, zone 21 mm; cefotaxime 30 µg, zone 14 mm; cefotaxime-clavulanate 30/10 µg, zone 23 mm; meropenem, zone 28 mm (susceptible). What does this pattern show?

After emptying a patient's urinary catheter bag while wearing gloves, a ward nurse takes off her gloves. What should she do next?

A meropenem-resistant Klebsiella pneumoniae grows from an ICU patient's blood. Which test shows whether a carbapenemase causes the resistance?

Staphylococcus aureus grows from a post-operative wound swab in the orthopaedic ward. On CLSI disc diffusion, the cefoxitin 30 µg zone is 18 mm (susceptible 22 mm or more; resistant 21 mm or less). Penicillin is resistant and vancomycin MIC is 1 µg/mL. What does the cefoxitin result indicate?

A staff nurse is about to enter the isolation room of a man with sputum smear-positive pulmonary tuberculosis. She will wear the respirator shown. Which step must she do every time she puts it on?