Infection Prevention, Sterilisation and Stewardship

Microbiology — Infection Prevention and Control, NMC MBBS licence examination syllabus (Nepal Medical Council).

Infection prevention and control

The interventions here are cheap, proven, and reliably skipped.

Infection prevention is unusual in medicine: the evidence is strong, the measures are inexpensive, and compliance is nonetheless poor. Nobody disputes that hand hygiene works. Observed compliance rates in hospitals worldwide are nonetheless consistently far below what staff believe they achieve — which tells you the problem is behavioural rather than technical.

That matters for a licensing examination because the examinable content is mostly about systems and habits rather than microbiology: when to clean your hands, what precautions to add and when, how instruments are processed, what to do after a needlestick, and why the antibiotic you start today shapes the resistance somebody else faces next year.

🩺 Where this lives: Antimicrobial resistance is a problem created one prescription at a time and paid for collectively. The antibiotic given "just in case" to a patient who did not need it produces no benefit for that individual, and contributes to a resistance pattern that will one day mean a colleague has nothing effective to offer. In settings where antibiotics are available without prescription and courses are frequently incomplete, that pressure is intense. Stewardship is not bureaucratic interference — it is the recognition that antibiotics are a shared resource that can be exhausted.

💡 A note on scope. This chapter gives no doses, no post-exposure prophylaxis regimens, no numerical per-exposure transmission risks and no autoclave temperatures. PEP follows the national guideline; published risk figures vary by source and exposure type; sterilisation parameters are equipment-specific. Antibiotic classes and resistance mechanisms are in the Antibiotics chapter, surgical site infection in the Wounds chapter, outbreak investigation in the Communicable Disease Control chapter, and blood-borne viruses in the HIV and Hepatitis chapter.

Hand hygiene

The point most often missed is that hand hygiene before patient contact matters as much as after. Cleaning your hands after seeing a patient protects you and the next person; cleaning them before protects this patient from whatever you have just been touching. Both directions matter, and the "before" moments are the ones most frequently omitted — precisely because there is no visible reason to bother.

ALCOHOL RUB OR SOAP AND WATER? ALCOHOL HAND RUB is faster, more accessible at the bedside, and better tolerated by the skin — which is why it improves compliance in practice. Use it when hands are not visibly soiled. SOAP AND WATER is required when: Hands are VISIBLY SOILED or contaminated with body fluid Dealing with SPORE-FORMING organisms, where alcohol is not reliably effective and the mechanical action of washing is needed THE PRACTICAL POINTS THAT DEFEAT GOOD INTENTIONS: Rings, wrist watches and long sleeves prevent adequate decontamination Long or artificial nails harbour organisms GLOVES ARE NOT A SUBSTITUTE. Hands must be cleaned after removing them — gloves develop microscopic defects and hands are contaminated during removal. A useful reframing: hand hygiene is not about whether your hands look dirty. It is about the fact that you cannot see what is on them.

Standard and transmission-based precautions

💡 Exam angle: the key principle is that standard precautions apply to every patient, always — not only to those known to be infected. The logic is straightforward: at any moment a proportion of your patients have an undiagnosed transmissible infection, so precautions applied selectively to "known" cases miss exactly the people you did not know about. Transmission-based precautions are then added for specific organisms — contact, droplet or airborne, the last requiring a respirator rather than a surgical mask, as for tuberculosis.

Cleaning, disinfection and sterilisation

Two ideas carry this section. First, cleaning always comes first — organic material shields organisms, so neither disinfection nor sterilisation works reliably on a dirty instrument. Second, the level of processing is decided by where the instrument goes: anything entering sterile tissue or the bloodstream must be sterilised, anything touching mucous membranes needs high-level disinfection, and anything touching only intact skin needs cleaning or low-level disinfection. The distinguishing feature of sterilisation is that it destroys spores.

Sharps and needlestick injury

WHAT TO DO AFTER A NEEDLESTICK IMMEDIATELY Wash the area with soap and running water Encourage bleeding gently Do NOT scrub, and do NOT apply bleach or caustic antiseptics — they damage tissue without reducing risk THEN, AND THIS IS THE PART PEOPLE DELAY REPORT IT AT ONCE through the local procedure. Risk assessment and post-exposure prophylaxis are TIME- CRITICAL, and PEP loses effectiveness with delay. THE RISK RANKING IS WORTH KNOWING: HEPATITIS B carries the highest transmission risk of the three after a percutaneous exposure HEPATITIS C is intermediate HIV carries the lowest — though it attracts the most fear Numerical risks per exposure vary between published sources and by exposure type; take them, and the PEP regimen, from your national guideline. THE PREVENTABLE PART: HEPATITIS B IS VACCINE-PREVENTABLE, and every healthcare worker should be immunised before clinical exposure. This is one of the clearest cases in medicine where the intervention is unarguable — and where students and junior staff are frequently unvaccinated. NEVER RE-SHEATH A NEEDLE. Most needlestick injuries happen during or after use, not during the procedure itself, and re-sheathing is a leading mechanism.

Healthcare-associated infection and stewardship

💡 Exam angle: most healthcare-associated infections are device-associated — urinary catheters, cannulae and central lines, ventilators, and surgical wounds. That gives one high-yield behaviour: ask every day whether the device is still needed, because the most effective prevention is early removal. For antibiotics, the examinable framework is "start smart, then focus": culture before starting where possible, and review at 48–72 hours to stop, narrow the spectrum, or switch to oral.

Clinical reasoning: four scenarios

🔍 Case 1 — gloves instead of hands

ScenarioA doctor moves between four patients on a ward wearing the same pair of gloves, explaining that gloves protect against transmission and that his hands stay clean underneath.

Two errorsGloves worn between patients, and gloves treated as a substitute for hand hygiene.

ReasoningGloves become contaminated exactly as hands do and transfer organisms between patients. They also develop microscopic defects, and hands are contaminated during removal.

AnswerChange gloves between patients where they are indicated at all, and clean hands after removing them — every time.

🔍 Case 2 — the needlestick reported next week

ScenarioA medical student sustains a needlestick from a patient of unknown status. Embarrassed, she washes the site with bleach, tells nobody, and mentions it a week later. She has never been vaccinated against hepatitis B.

Three problemsBleach, delay, and no vaccination.

ReasoningCaustic agents damage tissue without reducing transmission. Risk assessment and PEP are time-critical, and a week's delay removes most of the benefit. Hepatitis B carries the highest transmission risk and is entirely vaccine-preventable.

AnswerAssess and manage per the national guideline even at this stage, arrange hepatitis B vaccination, and address the reporting culture — students conceal these injuries when they fear blame.

🔍 Case 3 — the catheter nobody questioned

ScenarioA patient catheterised on admission for monitoring is now mobile and eating. On day nine the catheter is still in place, and he develops fever with a positive urine culture. Antibiotics are started; the catheter stays.

Missing questionDoes he still need the catheter?

ReasoningCatheter-associated urinary infection risk rises with every day of use, and the most effective intervention is removal. Treating the infection while leaving the device in place addresses half the problem.

AnswerRemove the catheter if there is no continuing indication, treat per local guidance, and build the daily device review into practice.

🔍 Case 4 — day five and nobody has looked

ScenarioA patient started on broad-spectrum intravenous antibiotics for a chest infection is much improved by day three, eating and afebrile. Cultures grew a sensitive organism. On day five the same intravenous broad-spectrum regimen continues unchanged.

Missed stepThe 48–72 hour review.

Reasoning"Start smart, then focus" requires an active review: narrow the spectrum to the cultured organism, switch from intravenous to oral once the patient is improving and absorbing, and set a stop date. Continuing broad-spectrum therapy adds resistance pressure, line risk and cost without benefit.

AnswerReview, narrow, switch to oral and document a duration. The review is the intervention.

Commonly confused

Confusion	The distinction	Why it matters
Gloves vs hand hygiene	Gloves are not a substitute	Hands are contaminated on removal.
Before vs after patient contact	Before protects the patient	The most commonly omitted moments.
Alcohol rub vs soap and water	Soap for soiled hands and spores	Alcohol is unreliable against spores.
Standard vs transmission-based	Standard applies to everyone, always	You do not know who is infected.
Surgical mask vs respirator	Airborne precautions need a respirator	Relevant to tuberculosis.
Disinfection vs sterilisation	Only sterilisation kills SPORES	Decides how instruments are processed.
Cleaning vs processing	Cleaning must come first	Organic matter shields organisms.
Treating infection vs removing the device	The device is the source	Antibiotics alone leave it in place.

Rapid revision

MUST-KNOW FACTS 1. HAND HYGIENE is the single most effective measure — and the least complied with. 2. Clean hands BEFORE as well as AFTER patient contact. 3. BEFORE protects the patient; AFTER protects you and others. 4. ALCOHOL RUB when hands are not visibly soiled. 5. SOAP AND WATER when soiled, and for SPORE-forming organisms. 6. GLOVES ARE NOT A SUBSTITUTE — clean hands after removing them. 7. Change gloves between patients. 8. Rings, watches and long sleeves prevent adequate decontamination. 9. STANDARD PRECAUTIONS apply to EVERY patient, ALWAYS. 10. They exist because you do not know who is infected. 11. TRANSMISSION-BASED precautions are ADDED, not substituted. 12. CONTACT: gloves and apron · DROPLET: surgical mask. 13. AIRBORNE: RESPIRATOR mask and ventilation — as for TB. 14. CLEANING always comes FIRST — organic matter shields organisms. 15. DISINFECTION kills most organisms but NOT reliably spores. 16. STERILISATION destroys ALL organisms INCLUDING SPORES. 17. CRITICAL items (enter tissue or blood) → STERILISE. 18. SEMI-CRITICAL (touch mucosa) → high-level disinfection. 19. NON-CRITICAL (intact skin) → clean or disinfect. 20. NEVER RE-SHEATH A NEEDLE. 21. Dispose of sharps at the point of use; never overfill containers. 22. After a needlestick: WASH with soap and water, encourage bleeding. 23. Do NOT scrub or apply bleach. 24. REPORT IMMEDIATELY — assessment and PEP are TIME-CRITICAL. 25. Transmission risk ranking: HEPATITIS B > HEPATITIS C > HIV. 26. HEPATITIS B IS VACCINE-PREVENTABLE — every health worker should be immunised. 27. Most healthcare-associated infections are DEVICE-ASSOCIATED. 28. Catheters, cannulae, central lines, ventilators, surgical wounds. 29. ASK DAILY whether each device is still needed — REMOVE IT EARLY. 30. STEWARDSHIP: right indication, drug, route and duration. 31. CULTURE BEFORE ANTIBIOTICS where possible. 32. REVIEW AT 48-72 HOURS: stop, narrow, or switch to oral. 33. Every unnecessary course selects resistance that outlives the patient.

💡 Exam angle: almost every question here has the same shape — a plausible shortcut is offered, and the answer is the unglamorous discipline. Gloves instead of handwashing, precautions only for known cases, antibiotics continued because the patient is improving, a catheter left because nobody asked. Recognise the shortcut and you have the answer.

Syllabus points

Why hand hygiene is skipped despite the evidence
The moments for hand hygiene
Alcohol rub versus soap and water
Why gloves are not a substitute
Standard precautions for every patient
Contact, droplet and airborne precautions
Cleaning, disinfection and sterilisation
Critical, semi-critical and non-critical items
Sharps safety and never re-sheathing
Managing a needlestick injury
The risk ranking and hepatitis B vaccination
Device-associated infection and early removal
Antimicrobial stewardship and the 48-72 hour review

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