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HOSPITAL INFECTION CONTROL — COMPLETE EXAM ANSWERS

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PART B: MODIFIED ESSAY QUESTIONS

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1. Hand Hygiene Methods, Steps, Products, and WHO Five Moments

Definition

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Methods of Hand Hygiene

• Used when hands are visibly dirty or soiled with blood/body fluids
• Also used after contact with Clostridium difficile or Bacillus anthracis (spores not removed by alcohol)
• Mechanism: Detergent action + mechanical friction removes transient flora and dirt

1. Wet hands with water; apply enough soap to cover all surfaces
2. Rub palms together
3. Rub back of each hand with the palm of the other hand, fingers interlaced
4. Rub palm to palm with fingers interlaced
5. Rub backs of fingers to opposing palms with fingers interlocked
6. Rotational rubbing of each thumb clasped in opposite hand
7. Rotational rubbing backwards and forwards with clasped fingers of right hand in left palm and vice versa
8. Rinse hands with water; dry thoroughly with single-use towel
9. Use towel to turn off the tap

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• Preferred method when hands are NOT visibly soiled (most efficient and convenient)
• More effective, requires only ~25% of the time compared to soap/water
• Mechanism: Denatures proteins of microorganisms
• 60-95% ethanol (or isopropanol) in aqueous base; ethanol preferred for better antiviral activity
• Effective against: gram-positive bacteria, gram-negative bacteria, lipophilic viruses (HSV, HIV, influenza, RSV), fungi
• NOT effective against: bacterial spores, C. difficile, B. anthracis, hydrophilic viruses (norovirus, Hepatitis A)

1. Apply a palmful of product in a cupped hand
2. Rub hands palm to palm
3. Right palm over left dorsum with interlaced fingers, and vice versa
4. Palm to palm with fingers interlaced
5. Backs of fingers to opposing palms with fingers interlocked
6. Rotational rubbing of left thumb clasped in right palm and vice versa
7. Rotational rubbing backwards/forwards with clasped fingers of right hand in left palm and vice versa
8. Allow to dry completely (do not wipe)

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• Used before performing surgical procedures
• Removes transient flora AND reduces resident flora
• Products: Chlorhexidine gluconate (4%) or Povidone-iodine scrub
• Chlorhexidine preferred - better residual/persistent activity (cationic biguanide, disrupts cell membranes); activity persists >6 hours
• Technique: Scrub hands and forearms up to elbows for minimum 2-5 minutes; use sterile brush for nails

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Products Used

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WHO Five Moments for Hand Hygiene

1. BEFORE touching a patient - To protect the patient against harmful germs carried on healthcare worker (HCW) hands
2. BEFORE a clean/aseptic procedure - To protect the patient against germs, including the patient's own, from entering the body (e.g., IV insertion, catheterization, wound dressing)
3. AFTER body fluid exposure risk - To protect HCW and healthcare environment from patient germs (e.g., after blood draw, urine handling)
4. AFTER touching a patient - To protect HCW and healthcare environment from patient germs
5. AFTER touching patient surroundings - To protect HCW and healthcare environment from patient germs, even if the patient was not touched (e.g., after touching bed rails, monitor)

Source: Barash, Cullen, and Stoelting's Clinical Anesthesia, 9e - Sherris & Ryan's Medical Microbiology, 8th Ed

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2. Major Types of HAIs, CAUTI - Definition, Etiopathogenesis, Risk Factors, Lab Diagnosis, Treatment

Definition of HAI

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Major Types of HAIs (By Site)

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CAUTI - Definition

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Etiopathogenesis of CAUTI

1. Extraluminal route (most common, ~66%): Microorganisms migrate along the outer surface of the catheter from the perineum/meatus. Occurs early and continuously during catheterization.
2. Intraluminal route (~34%): Organisms enter via the catheter lumen - contamination of the drainage bag, breaks in the closed drainage system, or retrograde flow.
3. Biofilm formation: Organisms (especially Staphylococci, E. coli, Proteus) adhere to the catheter surface and form a glycocalyx biofilm that:
   • Protects from antibiotics
   • Protects from host immune defenses
   • Serves as a persistent reservoir
   • Facilitates ascending infection
4. Ascending infection: Bacteria migrate from bladder to kidney causing pyelonephritis; may enter bloodstream causing urosepsis

• Escherichia coli (most common)
• Klebsiella pneumoniae
• Enterococcus spp.
• Candida spp. (common in ICU, prolonged catheterization, antibiotic use)
• Pseudomonas aeruginosa
• Proteus mirabilis
• Staphylococcus aureus

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Risk Factors for CAUTI

• Female sex (shorter urethra)
• Older age
• Diabetes mellitus
• Immunocompromised state
• Colonization of the meatus/rectum with uropathogens
• Severe underlying illness

• Duration of catheterization (single most important risk factor - risk increases ~3-7% per day)
• Breaks in aseptic technique during insertion
• Disconnection of closed drainage system
• Urine reflux from drainage bag
• Catheter material (latex > silicone for encrustation)

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Laboratory Diagnosis of CAUTI

• Leukocyte esterase positive (indicates pyuria)
• Nitrite positive (gram-negative organisms convert nitrate to nitrite)
• Sensitivity ~75%, Specificity ~82%

• Pyuria: >10 WBC/mm³ (or >5 WBC/HPF in centrifuged urine)
• Bacteriuria on Gram stain of uncentrifuged urine (1 organism/OIF ≈ 10⁵ CFU/mL)

• Catheter specimen urine (CSU): Threshold ≥10³ CFU/mL (symptomatic CAUTI)
• Midstream clean catch: ≥10⁵ CFU/mL
• Collect fresh sample from catheter sampling port (not drainage bag)
• Culture on CLED agar or Blood agar + MacConkey agar
• Antibiotic susceptibility testing (AST) mandatory

• If systemic sepsis suspected
• 2 sets from peripheral veins

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Treatment of CAUTI

• Remove or change catheter if possible (reduces organism load, removes biofilm)
• Treat only SYMPTOMATIC CAUTI (not asymptomatic bacteriuria, except pre-procedure)

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3. VAP - Risk Factors, Pathogenesis, Lab Diagnosis, Treatment

Definition

• Early-onset VAP (<5 days): Usually caused by antibiotic-sensitive organisms (MSSA, H. influenzae, S. pneumoniae)
• Late-onset VAP (>5 days): MDR organisms predominate (P. aeruginosa, MRSA, Acinetobacter)

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Risk Factors

• Severe underlying illness (APACHE II score)
• Immunocompromised state, malnutrition
• Prior antibiotic exposure (greatest risk - selects MDR organisms like P. aeruginosa)
• Impaired consciousness (reduces cough/gag reflex)
• Trauma, burns, ARDS
• Advanced age, COPD

• Endotracheal tube (bypasses natural mechanical defenses; main risk factor)
• Duration of mechanical ventilation (1% per day cumulative; up to 70% by day 30)
• Nasogastric tube (promotes aspiration, bacterial colonization)
• Reintubation

• Supine position (promotes aspiration)
• Sedation and neuromuscular blockade (reduces protective reflexes)
• Frequent ventilator circuit changes
• Inadequate hand hygiene

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Pathogenesis

1. Colonization of oropharynx with pathogens - Normal oral flora replaced by gram-negative pathogens, MRSA due to antibiotic pressure, cross-infection from other patients/contaminated equipment, severe illness, malnutrition
2. Aspiration into lower respiratory tract - Microaspiration of secretions pooling above the endotracheal tube cuff occurs in virtually all intubated patients. The endotracheal tube bypasses the epiglottis and cough reflex, facilitating aspiration. Bacteria also form a biofilm on the inner surface of the ETT; fragments are dislodged during suctioning, reseeding the trachea.
3. Compromise of host defenses - Severely ill/septic patients develop "immunoparalysis" days after ICU admission. Hyperglycemia and frequent transfusions further impair immune response. Colony counts rise to overwhelming levels before clinical VAP manifests.

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Laboratory Diagnosis

• New or progressive infiltrate on CXR/CT
• Fever (>38°C) or hypothermia
• Leukocytosis (>10,000) or leucopenia
• Purulent tracheal secretions
• Worsening oxygenation (PaO₂/FiO₂ ratio)

1. Endotracheal aspirate (ETA): Simple, non-invasive; threshold ≥10⁵ CFU/mL; high sensitivity but low specificity (colonization)
2. Bronchoalveolar lavage (BAL): Gold standard; threshold ≥10⁴ CFU/mL; high sensitivity and specificity; requires bronchoscopy
3. Protected specimen brush (PSB): Threshold ≥10³ CFU/mL; best specificity; used when BAL not possible
4. Blind BAL / Mini-BAL: Non-bronchoscopic BAL; useful when bronchoscopy unavailable
5. Gram stain of secretions: Rapid (results within hours); guides initial therapy
6. Blood cultures: Positive in only 10-20%; useful if positive
7. Lung biopsy: Reserved for non-responsive, immunocompromised patients

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Treatment of VAP

• Start empirical therapy promptly (delay worsens outcomes)
• De-escalate based on culture results

• Ceftriaxone, or
• Piperacillin-tazobactam, or
• Levofloxacin/moxifloxacin

• Anti-pseudomonal beta-lactam (Pip-tazo or Cefepime or Imipenem/Meropenem) PLUS
• Anti-pseudomonal fluoroquinolone (Ciprofloxacin) or aminoglycoside (Amikacin/Tobramycin) PLUS
• If MRSA risk: Add Vancomycin or Linezolid

• A = Assess sedation (daily sedation vacation, spontaneous breathing trials)
• B = Bed head elevation 30-45°
• C = Chlorhexidine oral decontamination
• D = Drainage of subglottic secretions
• E = Enteral feeding (avoid gastric overdistension)

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4. Sterilisation and Disinfection - Definitions; Steam Steriliser (Autoclave) - Principle, Uses, Advantages, Disadvantages

Definitions

• High-level disinfection (HLD): Kills all organisms except high numbers of spores (e.g., glutaraldehyde, hydrogen peroxide)
• Intermediate-level disinfection: Kills mycobacteria, vegetative bacteria, most viruses, fungi but not spores (e.g., alcohols, iodophors)
• Low-level disinfection: Kills most vegetative bacteria, some fungi, some viruses (e.g., quaternary ammonium compounds)

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Steam Steriliser (Autoclave)

Principle

• The latent heat of vaporization of steam makes it far more effective than dry heat at the same temperature.
• When steam contacts cooler objects, it condenses and releases large amounts of heat, rapidly raising the object's temperature.

Operating Parameters

Components and Diagram

                    ┌─────────────────────────────────┐
                    │         AUTOCLAVE                │
     Steam Inlet ──►│  ┌─────────────────┐            │
     (from boiler)  │  │   CHAMBER       │◄── Safety  │
                    │  │   (with load)   │    Valve   │
     Pressure ─────►│  │                 │            │
     Gauge          │  └─────────────────┘            │
                    │         │                        │
     Thermometer ──►│    Drain/Vent                   │
                    │  (Air removal port)              │
                    │                                  │
     Door with ─────►  Locking mechanism              │
     gasket         └─────────────────────────────────┘

• Outer cylindrical chamber (withstands pressure)
• Inner sterilization chamber (holds the load)
• Steam supply inlet and steam trap
• Pressure gauge and safety valve
• Thermometer
• Air exhaust valve/drain
• Door with locking mechanism and rubber gasket
• Jacket (in modern autoclaves) maintains temperature

Process

1. Load materials (wrapped instruments, linen, culture media) into chamber
2. Door sealed (airtight)
3. Steam admitted from above/sides; air (heavier) sinks and escapes through bottom drain
4. Chamber reaches desired temperature/pressure
5. Holding time maintained (15-20 min at 121°C)
6. Steam released; vacuum drying cycle (removes moisture)
7. Door opened; materials retrieved

Uses

• Surgical instruments and drapes
• Gloves, gowns, linen
• Culture media preparation
• Dressings and bandages
• Hollow instruments (with proper cycle)
• Pharmaceutical preparations

Advantages

• Most reliable, effective method of sterilization (gold standard)
• No toxic residues
• Penetrates packaging well
• Fast (15-20 minutes)
• Economical and reproducible
• Can sterilize liquids (aqueous solutions, culture media)

Disadvantages

• Cannot be used for heat-labile materials (plastics, rubber goods, electronic equipment, optical instruments, certain drugs)
• May cause rust/corrosion of carbon steel instruments
• Wet load if drying cycle inadequate ("wet packs")
• Complex monitoring required
• Air pockets (if not evacuated) prevent steam penetration → sterilisation failure

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5. Classification of Chemical Sterilants and Their Application in Healthcare

Classification

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• Ethylene oxide (ETO): Alkylating agent; sterilizes heat/moisture-labile items; toxic, explosive, requires long aeration; used for medical devices, plastics, rubber
• Formaldehyde: Alkylating agent; used for OT fumigation, cabinet sterilization; toxic and carcinogenic
• Hydrogen peroxide vapor / Plasma sterilization: Non-toxic, rapid; for heat-labile items

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Applications in Healthcare

• Surgical site skin preparation: Chlorhexidine-alcohol (preferred); Povidone-iodine-alcohol
• Hand hygiene: ABHR (alcohol-based), CHG surgical scrub
• Endoscope disinfection/sterilization: Glutaraldehyde, OPA, peracetic acid (automated)
• Blood spills: 1% hypochlorite (10,000 ppm available chlorine)
• Surface disinfection: Phenolics, QACs, hydrogen peroxide, alcohols
• Drinking water: Chlorination (0.2-0.5 ppm free chlorine)
• Non-critical medical devices: 70% alcohol, QACs
• Heat-labile instruments: ETO gas or plasma sterilization

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6. Biomedical Waste - Definition, Segregation, Treatment and Disposal

Definition

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Segregation of Biomedical Waste (Colour-Coded Bags/Containers)

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Treatment and Disposal Methods

• Destroys waste by high-temperature combustion (800-1000°C)
• Used for anatomical waste, cytotoxics, animal waste, pathological waste
• Types: double-chamber pyrolytic incinerators
• Produces ash (safe for landfill) and flue gases

• Used for microbiology waste, sharps after disinfection
• Autoclave: 121°C at 15 psi for 30-60 min
• Microwave: 95°C for defined time
• After treatment, waste goes to landfill

• Used for liquid wastes, blood, body fluids
• 1% hypochlorite for blood/secretions; 2% glutaraldehyde for reusable equipment
• Treated liquid drained to ETP (effluent treatment plant)

• For anatomical waste when incineration unavailable
• Pit lined with lime, covered with 50 cm soil
• Only permitted in rural/remote areas

• For sharps after autoclaving; destroys to prevent reuse
• Mutilated sharps go to secure landfill

• For non-recyclable, treated solid waste
• Lined pits with leachate collection

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7. Antimicrobial Stewardship Program (AMSP)

Definition

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Need for AMSP in Healthcare Settings

1. Growing antimicrobial resistance - Overuse/misuse selects for resistant organisms (MRSA, ESBL, CRE, VRE); a "post-antibiotic world" is approaching in some geographic areas
2. Pharmaceutical costs - Antibiotics are the largest and fastest-growing drug expenditure in hospitals
3. Adverse effects - Antibiotic-associated diarrhoea, C. difficile colitis, allergic reactions, nephrotoxicity, hepatotoxicity
4. Ecological impact - Broad-spectrum antibiotics disrupt normal flora; promote emergence of resistant organisms
5. Inadequate empirical therapy - Incorrect antibiotic choice/dose increases mortality in sepsis
6. Limited new antibiotic pipeline - Only a few new antibiotics are being developed, making preservation of existing antibiotics critical

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Strategies of AMSP (CDC Core Elements)

1. Leadership commitment - Hospital leadership dedicates human, financial, and IT resources
2. Accountability - Appoint an infectious diseases physician/microbiologist as program leader; co-lead with clinical pharmacist
3. Pharmacy expertise - Pharmacist co-leads implementation to improve antibiotic use

1. Prior authorization (Preauthorization/Formulary restriction):
   • Certain broad-spectrum antibiotics (carbapenems, linezolid, daptomycin, antifungals) require approval from ID physician/microbiologist before prescribing
   • Prevents inappropriate use; most immediately effective strategy
2. Prospective audit and feedback:
   • Review of ongoing antibiotic prescriptions by stewardship team
   • Feedback given to prescribers with recommendations for de-escalation, dose optimization, IV-to-oral switch
   • Best evidence-based strategy
3. De-escalation:
   • Narrow spectrum once culture/sensitivity results available
   • Step down from IV to oral when clinically appropriate
4. Duration of therapy guidelines:
   • Set standard treatment durations to avoid unnecessarily prolonged courses
5. Dose optimization:
   • Correct dosing based on PK/PD principles, renal/hepatic function, therapeutic drug monitoring (e.g., vancomycin, aminoglycosides)
6. IV to oral conversion (IV-to-PO switch):
   • Switch to equivalent oral agents as soon as clinical condition permits; reduces length of stay, costs, and IV-related complications

• Tracking: Monitor antibiotic use (DDDs - Defined Daily Doses, DOT - Days of Therapy), resistance patterns, C. difficile rates
• Reporting: Regular reports on antibiotic use and resistance to prescribers, pharmacists, and hospital leadership
• Hospital Antibiogram: Annual cumulative antibiogram to guide empirical therapy

• Educate prescribers, pharmacists, nurses about adverse reactions, resistance, optimal prescribing
• Regular case-based CME sessions

Source: Goldman-Cecil Medicine, CDC Core Elements of Hospital Antibiotic Stewardship Programs

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PART C: SHORT STRUCTURED QUESTIONS

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C-1. HAI - Definition, Sources, Factors, Organisms

Definition

Sources of HAIs

1. Endogenous (autologous): Patient's own flora (skin, bowel, respiratory tract) - most common in immunocompromised patients
2. Exogenous:
   • Patients (cross-infection): Most important source; organisms transferred between patients
   • Staff: Nasal carriage of S. aureus, throat carriage of Streptococcus, gut carriage of Salmonella
   • Environment: Hospital dust, linen, air, sinks, drains, door handles, medical equipment

Factors Affecting HAIs

Organisms Implicated

• Staphylococcus aureus (MRSA) - wound, skin, BSI, VAP
• Coagulase-negative Staphylococcus - CRBSI, prosthetics
• Enterococcus spp. (VRE) - UTI, BSI, wound
• E. coli, Klebsiella, Proteus - UTI, BSI
• Pseudomonas aeruginosa - VAP, wound, UTI
• Acinetobacter baumannii (MDR) - VAP, BSI
• Clostridioides difficile - antibiotic-associated diarrhoea/colitis
• Candida spp. - CAUTI, CRBSI (immunocompromised)

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C-2. Modes of Transmission, Standard Precautions, Blood Spill Management

Modes of Transmission

1. Contact transmission (most common): Direct (hand-to-patient), indirect (contaminated object/surface), droplet contact
2. Droplet transmission: Large droplets (>5µm) from respiratory tract during coughing, sneezing, talking; travel <1 metre
3. Airborne/aerosol transmission: Small particles ≤5µm that remain suspended in air for prolonged periods; travel >1 metre
4. Common vehicle: Contaminated food, water, medications, blood products
5. Vector-borne: Insects (mosquitoes, flies) - less relevant in healthcare settings

Standard Precautions (Applied to ALL patients, regardless of diagnosis)

1. Hand hygiene - before/after all patient contact
2. Gloves - when contact with blood, body fluids, mucous membranes, non-intact skin
3. Mask, Eye protection, Face shield - when splash/spray of blood/body fluids anticipated
4. Gown - when clothing likely to be soiled with blood/body fluids
5. Safe injection practices - no needle recapping; sharps disposal in puncture-proof containers
6. Respiratory hygiene/cough etiquette - masks for coughing patients
7. Safe handling of potentially contaminated equipment - clean/disinfect/sterilize appropriately
8. Environmental cleaning - regular disinfection of surfaces
9. Handling of linen - contain soiled linen, avoid contamination of clothing/surfaces
10. Waste management - segregate and dispose per BMW rules

Management of Blood Spill

1. Wear PPE - heavy duty gloves, apron, mask, eye protection
2. Contain the spill - pour 1% hypochlorite (10,000 ppm) on/around the spill; leave for 10 minutes
3. Remove the spill - use disposable paper towels/absorbent material to wipe up from outside in; place in yellow waste bag
4. Decontaminate the area - clean with detergent and water; then apply 1% hypochlorite again; leave for 10 minutes; wipe
5. Dispose of PPE and cleaning materials - in appropriate waste stream
6. Wash hands thoroughly with soap and water after glove removal
7. Document - record incident; if HCW exposure occurred, initiate PEP protocol

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C-3. Personal Protective Equipment (PPE) - Types, Donning, Doffing

Types of PPE Used in Healthcare

1. Gloves (non-sterile latex/nitrile/vinyl; sterile surgical gloves)
2. Mask: Surgical/procedure mask (standard), N95 respirator (airborne precautions)
3. Eye protection: Goggles (tight-fitting), face shield (covers eyes, nose, mouth)
4. Gown/apron: Fluid-resistant gown (disposable/reusable), plastic apron
5. Cap/Head cover: Bouffant cap or surgical hood
6. Shoe covers/Boot covers
7. Full-face respirator (PAPR - powered air purifying respirator) for highest-risk procedures

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Steps of Donning PPE (GLOVES LAST)

1. Perform hand hygiene
2. Put on gown (fasten at back)
3. Put on surgical cap
4. Put on mask (mold to nose; secure ties/ear loops; check seal for N95)
5. Put on eye protection (goggles or face shield)
6. Put on gloves (last, pull over gown cuffs)

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Steps of Doffing PPE (GLOVES FIRST - most contaminated; MASK LAST - partially protects face)

1. Remove gloves - Pinch outside of one glove near wrist; pull off inside-out; hold in doffed hand; slide fingers under cuff of other glove; pull inside-out over first glove; discard
2. Perform hand hygiene
3. Remove eye protection - Handle by headband/earpieces, not face; place in disinfectant container
4. Perform hand hygiene
5. Remove gown - Unfasten ties; pull from back; roll outside in; discard
6. Perform hand hygiene
7. Remove mask - Handle by ear loops/ties only, NOT the front; discard
8. Perform hand hygiene
9. Remove cap - From behind, rolling forward; discard

Precautions During Doffing

• Never touch the front/inside of the mask
• Never touch eyes, nose, or mouth during doffing
• Perform hand hygiene between each step
• Doff in a designated area (anteroom)
• Each item immediately disposed of in appropriate waste container
• All doffing steps should be performed with assistance/buddy system for checking

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C-4. Agents Transmitted by Contact and Infection Control Measures

Agents Transmitted by Contact

• MRSA (Methicillin-resistant Staphylococcus aureus)
• VRE (Vancomycin-resistant Enterococcus)
• Clostridioides difficile (also requires soap/water hand hygiene, not ABHR)
• ESBL/CRE producing organisms (Klebsiella, E. coli, Acinetobacter)
• Herpes simplex virus (cutaneous)
• Scabies (Sarcoptes scabiei)
• Pediculosis
• Impetigo (Staphylococcus, Streptococcus)
• RSV (Respiratory Syncytial Virus) - also droplet

Infection Control Measures (Contact Precautions)

1. Private room or cohort with same-organism patients
2. Gloves: Wear on entering the room; change after contact with infective material; remove before leaving
3. Gown: Wear on entering the room; remove before leaving; discard
4. Hand hygiene: After removing gloves; use soap and water (not ABHR alone) for C. difficile
5. Dedicated patient equipment: Stethoscope, BP cuff, thermometer, etc. remain in room; disinfect before removal
6. Limit patient transport - necessary transport only; inform receiving area
7. Environmental cleaning: Daily and terminal cleaning with appropriate disinfectants (10% hypochlorite for C. difficile; phenolics/QACs for MRSA)
8. Signage: Contact precautions sign on room door
9. Visitor education: Instruct on hand hygiene and PPE use
10. Screening and decolonization: Active surveillance cultures for MRSA; nasal mupirocin + CHG body wash for decolonization

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C-5. Agents Transmitted by Droplets and Infection Control Measures

Agents Transmitted by Droplets (>5µm particles, <1 metre range)

• Influenza A and B virus
• Bordetella pertussis (whooping cough)
• Neisseria meningitidis
• Haemophilus influenzae type b
• Group A Streptococcus (invasive)
• Mumps virus
• Rubella virus
• Adenovirus
• SARS-CoV-2 (predominantly droplet + contact)
• Mycoplasma pneumoniae
• Rhinovirus

Infection Control Measures (Droplet Precautions)

1. Private room (preferred) - if unavailable, keep bed distance >1 metre with curtain barrier; cohorting with same pathogen patients acceptable
2. Surgical mask: HCW wears when within 1 metre of patient; patient wears mask when being transported
3. Eye protection: Goggles or face shield when within 1 metre (especially for respiratory secretions)
4. Gloves and gown: Standard precautions
5. Hand hygiene: Before and after patient contact
6. Spatial separation: Keep patient >1 metre from others; avoid crowded areas
7. Limit patient transport - patient wears mask during transport
8. Visitor restriction and education
9. Respiratory hygiene and cough etiquette: Tissues, cover cough, hand hygiene, surgical mask for patients
10. Duration: Maintain precautions for duration of illness

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C-6. Airborne Transmitted Agents and TB Infection Control

Agents Transmitted by Aerosols (<5µm particles, survive in air for hours)

• Mycobacterium tuberculosis (TB)
• Measles virus (Rubeola)
• Varicella zoster virus (Chickenpox/Disseminated zoster)
• Smallpox (Variola)
• Possible: SARS-CoV-2 (aerosol-generating procedures), SARS, MERS
• Histoplasma capsulatum, Coccidioides immitis (environmental aerosols)

Infection Control for Tuberculosis

• Identify and isolate suspect/confirmed TB patients promptly
• Airborne Infection Isolation Room (AIIR): Negative pressure room (≥12 air changes/hour); air exhausted directly outside or HEPA filtered before recirculation; door kept closed
• Triage protocols - separate coughing patients early
• Limit aerosol-generating procedures (intubation, bronchoscopy, sputum induction)
• Signage and visitor restriction

• Maintain negative pressure in isolation rooms (-2.5 Pa relative to corridor)
• HEPA filtration of recirculated air
• UV germicidal irradiation (UVGI) - upper room germicidal lamps
• Adequate ventilation (minimum 12 ACH in isolation rooms)

• HCWs must wear N95 particulate respirators (or equivalent: FFP2/FFP3) - minimum assigned protection factor 10
• Must be fit-tested and seal-checked before each use
• Surgical mask is INSUFFICIENT for airborne precautions
• Patients wear surgical mask when outside isolation room

• Contact tracing and screening of exposed HCWs (TST/IGRA)
• BCG vaccination of HCWs in high-burden countries
• Directly Observed Therapy (DOT) to ensure treatment completion
• Sputum clearance before removing isolation precautions (typically 3 negative AFB smears)
• Case notification to health authorities

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C-7. Hospital Infection Control Committee (HICC)

Constitution

1. Chairperson - Medical Superintendent / Hospital Director
2. Hospital Infection Control Officer (HICO) - Infectious diseases physician or medical microbiologist (secretary and operational head)
3. Infection Control Nurse (ICN) - full-time, trained; key operational role
4. Representative from - Surgery, Medicine, Pediatrics, Obstetrics
5. Microbiologist (if not HICO)
6. Pharmacist (antimicrobial stewardship)
7. Nursing superintendent
8. Hospital administrator
9. CSSD in-charge
10. Housekeeping supervisor
11. Biomedical engineer (sterilization equipment)
12. Environmental services representative
13. Quality/Accreditation coordinator

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Functions of HICC

1. Policy development: Formulate and review infection control policies, guidelines, and standard operating procedures (SOPs)
2. Surveillance: Establish and oversee HAI surveillance programs; analyze data; identify outbreaks
3. Education and training: Organize in-service training for all HCWs on hand hygiene, PPE, isolation precautions, waste management
4. Investigation of outbreaks: Identify source, mode of transmission; implement control measures; report to authorities
5. Antimicrobial stewardship: Oversee appropriate antibiotic use; maintain hospital antibiogram; formulary management
6. Monitoring and audit: Conduct regular audits of infection control practices (hand hygiene compliance, bundle adherence, PPE use)
7. Isolation and precaution protocols: Establish and update standard, contact, droplet, and airborne precaution guidelines
8. Sterilization and disinfection oversight: Monitor CSSD functioning, efficacy testing, equipment maintenance
9. BMW management oversight: Ensure compliance with BMW rules
10. Occupational health: Manage HCW exposures (NSI), vaccinations (HBV, influenza), health surveillance
11. New construction/renovation review: Assess infection control implications of building projects
12. Reporting: Submit reports to hospital administration; contribute to accreditation (NABH, JCI)

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C-8. CRBSI - Risk Factors, Pathogenesis, Lab Diagnosis, Treatment

Definition

Risk Factors

• Type of catheter: Central > peripheral; femoral/jugular > subclavian; multi-lumen > single-lumen
• Duration of catheterization (>4-7 days significantly increases risk)
• Insertion technique (non-sterile, emergency insertion)
• Site preparation (CHG-alcohol preferred)
• Catheter care (dressing changes, hub manipulation)
• Patient factors: extremes of age, TPN, immunosuppression, neutropenia, burns, ICU
• Underlying disease severity

Pathogenesis

1. Skin-to-catheter migration (extraluminal): Skin organisms migrate along outer catheter surface from insertion site - most common mechanism for short-term catheters
2. Intraluminal contamination: Organisms enter through catheter hub during manipulation (most common for long-term catheters)
3. Hematogenous seeding: Distant infection seeds catheter
4. Infusate contamination: Rare
5. Biofilm formation: Organisms (especially CoNS, S. aureus, Candida) form biofilm on catheter surface protected from antibiotics and immune cells → persistent bacteremia

Laboratory Diagnosis

1. Blood cultures: ≥2 sets (1 from catheter + 1 peripheral); preferably before antibiotics
2. Differential time to positivity (DTP): Catheter blood culture positive ≥2 hours earlier than peripheral - highly specific for CRBSI (>120 min DTP has 91% sensitivity, 94% specificity)
3. Catheter tip culture: Remove catheter; roll tip 4 times across blood agar plate (Maki semi-quantitative roll technique); ≥15 CFU = significant colonization
4. Quantitative blood cultures: Catheter:peripheral ratio ≥3:1
5. Gram stain of blood/catheter
6. Fungal cultures if Candida suspected

Treatment

• Remove catheter (essential for MRSA, Candida, Pseudomonas, persistent bacteremia, tunnel/exit site infection, septic emboli)
• Catheter salvage possible only for CoNS infections, if patient stable, catheter necessary - use antibiotic lock therapy (ALT) + systemic antibiotics

• Cover CoNS and S. aureus: Vancomycin (covers MRSA, CoNS)
• Add gram-negative coverage (Pip-tazo or carbapenem) if ICU/immunocompromised
• Add antifungal (Echinocandin - Caspofungin/Micafungin) if Candida risk factors

• CoNS: Vancomycin 5-7 days (if catheter removed)
• MSSA: Nafcillin/Oxacillin (or Cefazolin) 14 days
• MRSA: Vancomycin or Daptomycin 14 days
• Candida: Echinocandin → fluconazole step-down; remove catheter; minimum 14 days after last positive culture

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C-9. SSI - Risk Factors, Pathogenesis, Lab Diagnosis, Treatment

Definition

• Superficial incisional SSI: Skin and subcutaneous tissue only
• Deep incisional SSI: Fascia and/or muscle layers
• Organ/space SSI: Any organ or space opened/manipulated during surgery

Risk Factors

• Obesity (BMI >30)
• Diabetes mellitus (hyperglycemia impairs neutrophil function)
• Malnutrition
• Smoking
• Immunosuppression (steroids, chemotherapy, HIV)
• Remote infection at time of surgery
• Prolonged preoperative hospitalization (>2 days)
• ASA score ≥3
• Advanced age

• Prolonged operative time (>2-4 hours)
• Emergency surgery
• Contaminated or dirty wound classification
• Inappropriate/inadequate antibiotic prophylaxis
• Inadequate skin preparation
• Preoperative shaving (blade shaving - increases micro-cuts)
• Hypothermia during surgery
• Blood transfusions
• Poor surgical technique (dead space, hematoma, inadequate hemostasis)
• Inadequate OT ventilation/air handling

Pathogenesis

• Organisms (endogenous skin flora, bowel flora; exogenous from OT environment/staff) contaminate the wound at time of surgery
• Key organisms: S. aureus (most common), CoNS, E. coli, Klebsiella, Pseudomonas, Enterococcus, Bacteroides (abdominal)
• Once inoculated, organisms evade host defenses (especially if tissue devitalized, foreign body present, hematoma/dead space)
• Biofilm formation on implants leads to persistent infection

Laboratory Diagnosis

1. Wound swab culture: From deep within wound (not surface); Gram stain + culture + AST
2. Pus/fluid aspiration: Collected under aseptic conditions; aerobic and anaerobic culture
3. Tissue biopsy: Most accurate; ≥10⁵ CFU/g tissue is significant
4. Blood cultures: If systemic sepsis/bacteremia suspected
5. Imaging: Ultrasound (collection), CT (deep/organ space SSI) to guide drainage

Treatment

1. Wound opening and debridement: Drain pus, excise necrotic tissue, irrigate with saline
2. Wound cultures before starting antibiotics
3. Antibiotics:
   • Superficial: Often wound care alone (no antibiotics unless cellulitis/systemic signs)
   • Deep/organ space: Antibiotics guided by culture
   • Empirical: Cefazolin (skin organisms); add metronidazole for abdominal/colorectal
   • MRSA suspected: Vancomycin
4. Surgical re-intervention: For deep/organ space SSI (re-exploration, lavage, drainage)
5. Implant removal may be necessary for implant-associated SSI

• Pre-op CHG shower, nasal decolonization (if MRSA carrier)
• Antimicrobial prophylaxis: Cefazolin within 60 min before incision; redose if surgery >4 hours
• Clip (not shave) hair; avoid hair removal if possible
• Maintain normothermia, normoglycemia intraoperatively
• Maintain tissue oxygenation (supplemental O₂)

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C-10. Care Bundle Approach for Prevention of Device-Associated Infections

CLABSI Prevention Bundle (Central Line Bundle)

1. Hand hygiene before insertion and manipulation
2. Maximal sterile barrier precautions during insertion (sterile gown, gloves, large sterile drape, mask, cap)
3. Chlorhexidine-alcohol skin antisepsis (superior to povidone-iodine)
4. Optimal site selection - subclavian vein preferred (avoid femoral); use ultrasound guidance
5. Daily review of catheter necessity - remove promptly when no longer needed
6. Chlorhexidine-impregnated dressing at insertion site
7. Scrub the hub - disinfect catheter connectors before accessing

CAUTI Prevention Bundle

1. Avoid unnecessary catheterization - use alternatives (external catheters, intermittent catheterization)
2. Proper insertion technique - aseptic technique; sterile equipment
3. Closed drainage system - maintain unobstructed, gravity-dependent flow; no dependent loops
4. Daily need assessment - remove catheter as soon as possible (nurse-driven removal protocols)
5. Hand hygiene before/after catheter care
6. Secure the catheter - prevent traction and movement
7. Perineal hygiene - daily cleaning with soap and water

VAP Prevention Bundle

1. Head of bed elevation 30-45° (prevents aspiration)
2. Daily sedation vacation + spontaneous breathing trial (reduces duration of ventilation)
3. Chlorhexidine oral decontamination (reduces oropharyngeal colonization)
4. Subglottic secretion drainage (specialized ETT with suction port)
5. Cuff pressure monitoring (maintain 20-30 cmH₂O to prevent microaspiration)
6. Ventilator circuit management - change only when soiled (not routinely)
7. Early enteral nutrition and glycemic control

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C-11. HAI Surveillance - Objectives and Methods

Objectives

1. Establish baseline infection rates (endemic rate)
2. Identify and monitor HAI trends over time
3. Detect outbreaks (epidemic infections) early
4. Identify risk factors and high-risk areas/patient populations
5. Evaluate effectiveness of infection control interventions
6. Guide resource allocation and priority setting
7. Meet regulatory, accreditation, and reporting requirements
8. Provide data for benchmarking with other institutions
9. Monitor antimicrobial resistance trends

Methods of HAI Surveillance

• Infection control nurses regularly visit wards, review charts, cultures
• Daily review of microbiology reports, fever charts, antibiotic starts
• Device-associated surveillance: Monitor CLABSI, CAUTI, VAP rates per 1000 device-days
• Surgical site infection surveillance: Follow up all surgical patients during admission and post-discharge (30-day follow-up)

• Clinicians/ward staff report infections voluntarily (under-reporting common)
• Used in resource-limited settings; less accurate

• Monitor microbiology lab reports for significant isolates (MRSA, VRE, MDR organisms)
• Easy to implement; misses infections without cultures ordered

• Focus on high-risk areas (ICU, surgical wards) or specific infections (CLABSI, VAP)
• Most cost-effective approach

• Survey all patients in hospital on a single day
• Quick snapshot; useful for establishing baseline and benchmarking

• Outcome: Measure infection rates
• Process: Measure compliance with prevention measures (hand hygiene rates, bundle compliance)

• Device-associated infection rate = (infections/device-days) × 1000
• Device utilization ratio = device-days/patient-days
• SSI incidence = (SSI/surgeries) × 100

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C-12. Plasma Sterilization - Principle and Uses

Principle

1. The chamber is evacuated to low pressure
2. Hydrogen peroxide (H₂O₂) solution (58%) is injected and vaporized - filling the chamber as H₂O₂ vapor
3. Radiofrequency energy is applied to create a plasma - a state of highly ionized gas consisting of reactive species (free radicals: hydroxyl radicals •OH, hydroperoxyl radicals •OOH, superoxide O₂•⁻)
4. These reactive free radicals have broad-spectrum antimicrobial activity - they destroy cell membranes, nucleic acids, and enzymes
5. At end of cycle, plasma recombines into water and oxygen - non-toxic residues
6. Typical cycle: 45-75 minutes at <50°C

• Diffusion phase: H₂O₂ vapor penetrates and contacts all surfaces
• Plasma phase: Radiofrequency energy generates plasma from residual H₂O₂

Uses

• Heat-sensitive and moisture-sensitive medical devices (cannot be autoclaved)
• Endoscopes (rigid and flexible)
• Fiber optic cables and light cords
• Electronic instruments, cameras, power instruments
• Polymers and rubber goods
• Delicate surgical instruments (microsurgery, ophthalmic)

Advantages

• Low temperature (<50°C) - safe for heat-labile items
• Short cycle time (45-75 min)
• Non-toxic residues (water + oxygen) - no aeration required
• No toxic effluents - environmentally safe
• Compatible with most plastics, metals, glass, rubber
• Can be used immediately after cycle

Limitations

• Cannot be used for:
  • Cellulose (absorbs H₂O₂): paper, linen, powders, liquids
  • Long narrow lumens (>1-2mm diameter, >31 cm length) - poor penetration
• High capital cost

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C-13. Hot Air Oven - Functioning, Uses, Advantages, Disadvantages

Principle

• Dry heat has lower penetrability than steam
• Protein coagulation requires higher temperatures without moisture
• Less efficient energy transfer

Construction and Functioning

• Electrically heated oven with thermostatic control
• Double-walled insulated chamber with internal fan (forced air circulation)
• Temperature monitored by thermometer in several positions
• Pufale (1992) design: Motorized fan for uniform heat distribution

Uses

• Glassware: Petri dishes, test tubes, flasks, syringes (glass)
• Metal instruments: Forceps, scissors, scalpels (carbon steel)
• Powders: Talc, zinc oxide, starch (cannot be autoclaved)
• Oils and waxes: Liquid paraffin, petroleum jelly, greasy substances (resist moisture penetration; unsuitable for autoclave)
• Anhydrous substances

Advantages

• Suitable for materials that cannot be penetrated by moisture
• No moisture - no corrosion/rust of instruments
• Suitable for powders, oils, waxes
• Inexpensive
• Materials are dry at end of cycle (no wet packs)
• Good for glass, metal items

Disadvantages

• Cannot be used for rubber, plastics, dressings, fabric (char/melt at high temperatures)
• Longer cycle time (compared to autoclave)
• Penetration is poor - items must be unwrapped/loosely packed
• Uneven heat distribution if convection inadequate
• No indicator (like TST tape) as reliable as autoclaving
• Not suitable for aqueous solutions or culture media

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C-14. Spaulding's Classification of Medical Devices

Three Categories

• Risk: High - directly contact sterile tissues; any microbial contamination causes infection
• Required processing: STERILIZATION (autoclave, ETO, plasma, chemical sterilization)
• Examples:
  • Surgical instruments (scalpels, forceps, clamps, retractors)
  • Cardiac catheters, implants, prostheses
  • Intravenous catheters, needles, syringes
  • Urinary catheters
  • Biopsy forceps

• Risk: Intermediate - mucous membranes resistant to common bacteria but not all organisms
• Required processing: HIGH-LEVEL DISINFECTION (HLD) minimum (glutaraldehyde, OPA, hydrogen peroxide, peracetic acid, chlorine-based); sterilization preferred when feasible
• Examples:
  • Flexible endoscopes (gastroscopes, colonoscopes, bronchoscopes)
  • Laryngoscope blades
  • Respiratory therapy equipment
  • Endotracheal tubes
  • Specula (vaginal, nasal)
  • Thermometers (rectal)
  • Cystoscopes

• Risk: Low - intact skin is an effective barrier; rarely involved in direct transmission
• Required processing: LOW-LEVEL DISINFECTION or CLEANING alone
• Examples:
  • Blood pressure cuffs
  • Stethoscopes
  • Electrocardiograph electrodes
  • Bedpans, urinals
  • Bed linens, furniture
  • Crutches, bed rails, call bells
  • Face masks (outer surface)

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C-15. Central Sterile Supply Department (CSSD)

Definition

Functions

1. Receive, decontaminate, clean, and inspect used instruments
2. Assemble, package, and label instrument sets
3. Sterilize using appropriate methods
4. Store sterile items under controlled conditions
5. Distribute to wards, OT, ICU, outpatient areas
6. Maintain quality control records and sterilization monitoring
7. Train staff in decontamination and sterilization practices

Layout (One-way flow/unidirectional workflow to prevent contamination)

[DIRTY/DECONTAMINATION ZONE]
         ↓
[INSPECTION & PACKAGING ZONE]
         ↓
[STERILIZATION ZONE]
         ↓
[STORAGE/CLEAN ZONE]
         ↓
[DISTRIBUTION TO USERS]

Zones

• Receives used, contaminated instruments
• Manual cleaning (brushing, rinsing) or automated washer-disinfectors (ultrasonic cleaners, washer-sterilizers)
• Staff wear heavy-duty PPE

• Cleaned items inspected for damage, functionality
• Assembled into sets; wrapped in sterilization packaging (crepe paper, non-woven fabric, blister packs)
• Labeled with contents, date, sterilizer, batch number, expiry date

• Contains autoclaves (multiple: gravity, high-vacuum, flash), ETO chambers, plasma sterilizers
• Loading, monitoring, unloading of sterilizers

• Enclosed, clean, temperature/humidity controlled environment
• Shelved and organized for easy retrieval
• FIFO (first in, first out) inventory

Sterilization Monitoring in CSSD

• Mechanical indicators: Temperature, pressure, time printouts from sterilizer
• Chemical indicators: Class 1 (process indicators/autoclave tape), Class 5/6 (integrating indicators) on each pack
• Biological indicators: Weekly (or each load for critical items) using Geobacillus stearothermophilus spore strips (autoclave) or Bacillus atrophaeus (ETO)
• Bowie-Dick test: Daily for pre-vacuum autoclaves (air removal efficacy test)

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C-16. Sterilization Indicators and Chemical Disinfectant Efficacy Tests

Types of Sterilization Indicators (ISO 11140)

• Change color/appearance to show item has been exposed to sterilization process
• Does NOT confirm sterilization achieved
• Examples: Autoclave tape (brown diagonal lines appear), colored dots on packaging
• Use: On outside of every pack/load

• Bowie-Dick test: Daily test in pre-vacuum autoclaves; detects air removal inadequacy; uniform color change = pass; non-uniform = air entrapment present

• Respond to one critical variable (e.g., temperature only)
• Limited utility

• Respond to two or more critical parameters (e.g., time and temperature)
• Examples: Heat-sensitive tapes with multiple variables

• Respond to all critical parameters (time, temperature, steam quality)
• Performance equal to biological indicators
• Use: Inside every pack (intra-pack)
• Example: 3M Comply SteriGage

• Calibrated to respond to specific cycles (e.g., 134°C/3 min high-vacuum)
• Most specific for cycle parameters

• Contain defined number of resistant bacterial spores:
  • Autoclave/Steam: Geobacillus stearothermophilus (formerly Bacillus stearothermophilus) - D-value at 121°C
  • ETO/Dry heat/Plasma: Bacillus atrophaeus (formerly B. subtilis var. niger)
  • Formaldehyde: B. stearothermophilus
• After exposure, incubate at 56°C (steam BI) or 37°C (ETO BI) for 48 hours
• Growth (turbidity) = sterilization failure; No growth = sterilization achieved
• Commercial self-contained BIs (SCBIs): Rapid readout in 1-3 hours
• Frequency: Weekly minimum; each load for implantable devices

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Tests for Efficacy of Chemical Disinfectants

• Compare efficacy of test disinfectant vs. phenol under identical conditions
• Phenol coefficient (PC) = dilution of test agent killing organisms ÷ dilution of phenol killing organisms
• PC >1 = more effective than phenol; PC <1 = less effective
• Chick-Martin test uses organic matter (yeast) to simulate "dirty conditions"

• Stainless steel carriers inoculated with test organisms (Salmonella choleraesuis, S. aureus, Pseudomonas aeruginosa)
• Carriers submerged in disinfectant at use-dilution for specified time
• Then transferred to neutralizing broth and incubated
• Growth = failure; No growth = pass
• Standard for testing surface disinfectants in USA

• Tests capacity of disinfectant to maintain activity in presence of organic load (serial organic challenges)
• Most relevant to real-world use conditions

• Quantitative suspension test (European standards)
• Test organism suspended in disinfectant; quantitative count of survivors

• Samples of disinfectant solution in actual clinical use tested for contamination
• Practical check of whether dilution/storage conditions are adequate

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C-17. Disinfection of Operation Theatre and Membrane Filters

OT Disinfection

• All surfaces cleaned with 1-2% phenolic compound or freshly prepared 1% sodium hypochlorite (for blood/body fluid contamination) after each operating list
• Sequence: Ceiling → walls → equipment → floor (top to bottom, inside to outside)
• Operating table, instrument trolleys, anesthesia machine, monitors wiped down with 70% isopropanol or 1% hypochlorite
• Floor mopped with phenolic disinfectant

• All moveable equipment removed; thorough cleaning of floor, walls, ceiling
• Flush HEPA filters if installed

• Formaldehyde fumigation: Formalin (40% HCHO) 2.5 mL/m³ + potassium permanganate 1.25 g/m³ (exothermic reaction generates formaldehyde gas)
  • Seal OT (tape all openings); leave for 12-24 hours; then neutralize with ammonia 17.5 mL/m³
  • Highly toxic, carcinogenic - avoid in occupied areas
• Hydrogen peroxide vapor (HPV): 6-35% H₂O₂ aerosolized into sealed room; 1-4 hours contact; residue dissipates naturally to water + O₂; preferred modern alternative to formaldehyde

• HEPA (High-Efficiency Particulate Air) filtration: Removes ≥99.97% of particles ≥0.3 µm
• Positive pressure ventilation: OT air pressure positive relative to corridor (prevents outside air ingress)
• Laminar Air Flow (LAF): Unidirectional air flow (vertical or horizontal) over operating field in orthopaedic/cardiothoracic OT; achieves <10 CFU/m³ air
• Minimum 20 air changes per hour (15 fresh air + 5 recirculated through HEPA)
• Air quality monitoring: Settle plates, active air sampling (Andersen sampler)

• Traffic control (minimize entry/exit)
• Staff wear OT-specific attire, masks
• No talking/coughing over sterile field
• Wet mopping (not dry sweeping)

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Membrane Filters

• Sterilization of heat-labile fluids: Serum, vaccines, antibiotic solutions, ophthalmic drops, IV solutions, enzyme preparations
• Removing bacteria from water (water purification)
• Air sterilization (HEPA filters in OT, LAF units, BSCs)
• Laboratory: Preparing sterile media, separating bacteria from viruses
• Counting bacteria in water (membrane filtration technique)

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C-18. Agents Transmitted by NSI, Needle Precautions, PEP Steps

Agents Transmitted by Needle Stick Injury (NSI)

• Hepatitis B virus (HBV): Highest risk per exposure (6-30% if source is HBeAg positive); survives on surfaces up to 7 days
• Hepatitis C virus (HCV): ~1.8% risk per hollow-bore needle stick from HCV+ source
• HIV: ~0.3% risk per hollow-bore needle percutaneous exposure from HIV+ source
• Other (rare): Hepatitis D (requires HBV co-infection), syphilis, malaria, EBV, CMV

Precautions for Handling Needles

1. No recapping of needles (most NSI occur during recapping)
2. If recapping necessary - use one-handed "scoop" technique
3. Immediately discard needles in puncture-proof sharps containers at point of use
4. Sharps containers must be:
   • Never filled beyond 3/4 full
   • Kept upright and stable
   • Sealed and disposed per BMW rules
5. Wear gloves for all procedures involving needles
6. Use safety-engineered devices (retractable needles, needleless systems) where available
7. Never pass needles hand-to-hand; place in tray and allow colleague to pick up
8. Never bend or break needles
9. Hepatitis B vaccination for all HCWs

Steps of Post-Exposure Prophylaxis (PEP) - General Approach

1. First aid immediately:
   • Wash wound with soap and running water for 15 minutes; allow to bleed
   • For eye/mucous membrane: Flush with water/saline for 15 minutes
   • Do NOT use bleach or disinfectant on wound; do NOT suck the wound
2. Report to supervisor/infection control officer
3. Assess source patient:
   • Test source patient for HIV, HBsAg, Anti-HCV (with consent)
4. Assess exposed HCW:
   • HBV vaccination status and anti-HBs titer
   • Baseline HIV, HBsAg, anti-HCV
5. Initiate PEP as indicated (within 72 hours for HIV; within 24 hours for HBV)
6. Follow up: Repeat serological testing at 6 weeks, 3 months, 6 months
7. Counseling: Use barrier contraception during follow-up period; avoid blood/organ donation
8. Document everything in NSI register

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C-19. PEP for HIV

Risk Assessment

• Percutaneous injury: ~0.3% per exposure
• Mucous membrane exposure: ~0.09%
• Intact skin exposure: <0.09%
• Higher risk: Deep injury, hollow-bore needle, visible blood on device, source with high viral load, terminal HIV illness

PEP Regimen (WHO/CDC 2016)

• Tenofovir (TDF) 300mg + Emtricitabine (FTC) 200mg [co-formulated as Truvada] ONCE daily PLUS
• Dolutegravir (DTG) 50mg ONCE daily (or Raltegravir 400mg twice daily)

• TDF/FTC + Lopinavir/ritonavir (LPV/r)

Follow-up Testing

• HIV antibody (4th generation Ag/Ab combo): Baseline, 6 weeks, 3 months, 6 months
• If source HIV-negative AND from low-prevalence area: PEP may be stopped
• If source untestable or unknown status in high-prevalence area: Treat as HIV+

Monitoring

• Side effects of PEP drugs: Nausea (most common), headache, fatigue, renal dysfunction (TDF)
• LFTs at baseline and at 2 weeks
• Adherence counseling

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C-20. PEP for Hepatitis B

Risk by Source Status

• Source HBsAg(+)/HBeAg(+): Risk ~22-31%
• Source HBsAg(+)/HBeAg(-): Risk ~1-6%
• Source unknown: Treat based on risk assessment

PEP Algorithm

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C-21. Monitoring AMSP Compliance; DDT and DOT Definitions

Monitoring Compliance

• DOT (Days of Therapy) and DDD (Defined Daily Doses) - see below
• Proportion of restricted antibiotics used with appropriate pre-authorization
• Time from culture result to antibiotic de-escalation
• Rates of IV-to-oral conversion
• Duration of antibiotic courses compared to guidelines
• Blood culture collection rate before antibiotic initiation

• HAI rates, CLABSI, CAUTI, VAP rates
• Clostridioides difficile infection rates (closely linked to antibiotic use)
• MDR organism rates (MRSA, VRE, ESBL, CRE)
• Hospital-acquired infection mortality

• Pharmacy data: Antibiotic purchase/dispensing records
• Electronic prescribing audits
• Point prevalence surveys (PPS) of antibiotic use
• Antibiogram monitoring (annual)

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Definitions

• The assumed average maintenance dose per day for a drug used for its main indication in adults, as defined by the WHO Collaborating Centre for Drug Statistics Methodology
• A technical unit of measurement for comparing antibiotic consumption between facilities and over time
• Not a prescription recommendation; does not reflect actual patient doses
• Expressed as DDD per 100 patient-days or 1000 patient-days
• Example: DDD for amoxicillin = 1.5g/day

• Counts each day a patient receives at least one antibiotic (regardless of dose or number of agents)
• More patient-centered than DDD; accounts for pediatric and adjusted doses
• Expressed as DOT per 1000 patient-days
• Preferred metric in pediatric settings and in facilities with dose adjustments

DDD is better for cross-facility/international comparisons; DOT is better for within-facility, patient-level monitoring

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C-22. Escalation/De-escalation and Hospital Antibiogram

Escalation Approach

• Start with narrow-spectrum empirical antibiotic based on likely pathogen and local antibiogram
• If patient does not respond (clinical deterioration, no improvement in 48-72 hours), escalate to broader-spectrum agent
• Culture results guide escalation decisions
• Indication: When initial antibiotic is clearly insufficient; resistant pathogen identified; deteriorating sepsis

De-escalation Approach

• Start with broad-spectrum empirical antibiotic (justified in severe sepsis, septic shock, ICU, immunocompromised) to ensure coverage
• Once culture/sensitivity results available (48-72 hours), narrow down to the most targeted, effective agent with the smallest spectrum
• Benefits: Reduces selective pressure for resistance, reduces CDI risk, reduces cost, reduces side effects
• Example: Initial Meropenem + Vancomycin → de-escalate to Cefazolin for MSSA bacteremia once results available

Hospital Antibiogram

• Definition: A compilation of susceptibility data of bacterial isolates obtained from a hospital's own patient population, summarized as percentage of isolates susceptible to each antibiotic
• Generated from clinical culture results over the previous year
• Published annually by the microbiology laboratory
• Uses:
  1. Guide empirical antibiotic therapy for HAIs
  2. Track resistance trends over time
  3. Identify emerging resistance patterns (e.g., increasing carbapenem resistance in Klebsiella)
  4. Inform formulary decisions for antimicrobial stewardship
  5. Benchmark with regional/national data
• Preparation: Only first isolate per patient per year; minimum 30 isolates per species; de-duplicate data
• Standard format: CLSI M39 guidelines

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C-23. Microbial Contamination of Water, Surveillance Methods, Eijkman Test

Classification of Microbial Contamination of Water

• Bacteria: Salmonella typhi, Vibrio cholerae, E. coli O157:H7, Campylobacter, Leptospira, Legionella
• Viruses: Hepatitis A, poliovirus, norovirus, rotavirus
• Protozoa: Giardia, Cryptosporidium (chlorine-resistant), Entamoeba

Methods of Water Surveillance

• Serial dilutions of water inoculated into lactose broth tubes
• Incubate 37°C/48h; gas/acid production = presumptive positive (coliforms)
• Confirmed by inoculation into brilliant green bile broth (BGLB) or EMB agar
• MPN index used to calculate coliforms per 100 mL
• WHO limit: 0 coliforms/100 mL (drinking water)

• 100 mL water filtered through 0.45 µm membrane
• Membrane placed on MacConkey/Endo agar or mFC broth agar
• Incubate; count colonies
• Metal-sheen colonies = coliform; blue colonies on mFC at 44°C = fecal coliforms
• More rapid and sensitive than MPN; gives direct colony count

• Simple screening; for treated water; detects presence of coliforms

Eijkman Test

• Purpose: Distinguishes fecal coliforms from non-fecal coliforms (confirms E. coli)
• Principle: E. coli (fecal) ferments lactose at 44-44.5°C producing acid and gas; environmental coliforms (Enterobacter, Klebsiella) do NOT ferment lactose at this elevated temperature
• Method:
  1. Take positive tubes from MPN presumptive test
  2. Transfer to lactose broth/EC broth
  3. Incubate at 44-44.5°C for 24-48 hours in water bath
  4. Gas production = positive for fecal coliforms (E. coli)
• Significance: Positive Eijkman test confirms fecal origin of contamination (public health significance is higher than non-fecal coliforms)

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C-24. Air Quality Evaluation in the Operation Theatre

Importance

Methods of Air Quality Monitoring

• Expose blood agar/nutrient agar plates (90mm Petri dishes) open in OT for 1 hour
• Incubate at 37°C for 48 hours + at room temperature for 48 hours
• Count colonies (CFU per plate per hour = marker of air contamination)
• Acceptability limits:
  • At rest (empty OT): <1 CFU/plate/hour
  • In operation: <180 CFU/m³ (with LAF) to <200-500 CFU/m³ (conventional ventilation)

• Andersen sampler / RCS (Reuter Centrifugal Sampler) / SAS (Surface Air System)
• Known volume of air (e.g., 1000 L) is drawn through sampler onto culture medium
• Results expressed as CFU per m³ of air
• More quantitative and reproducible than settle plates

• Electronic device counts airborne particles (0.5 µm, 5 µm)
• Used for ISO classification of clean rooms (ISO 14644)
• OT classification: ISO Class 7 (conventional) to ISO Class 5 (LAF)

Acceptability Criteria (OT Air Quality)

Parameters Monitored

1. Bacterial colony count (CFU/m³ or CFU/plate/hour) - settle plates + active sampling
2. Particle count (ISO classification)
3. Temperature and humidity (18-22°C; 40-60% relative humidity)
4. Pressure differential (positive pressure: +2.5 Pa relative to corridor)
5. Number of air changes/hour (minimum 20 ACH for conventional OT; 300-600 ACH for LAF)
6. HEPA filter efficiency testing (DOP/PAO integrity testing)

Organisms Monitored

• Staphylococcus aureus (shed from skin)
• Bacillus spp. (environmental; spore-forming)
• Aspergillus spp. (mold; fungal SSI in immunocompromised)
• Total aerobic count

Air Sampling Timing

• Baseline: After terminal cleaning, before cases
• Routine: Monthly (settle plates); quarterly (active sampling)
• After fumigation or renovation
• During outbreak investigation

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Sources: Sherris & Ryan's Medical Microbiology 8th Ed; Harrison's Principles of Internal Medicine 22nd Ed; Barash Clinical Anesthesia 9th Ed; Goldman-Cecil Medicine; Park's Textbook of Preventive and Social MedicineAll 31 questions have been comprehensively answered. Here is a structured summary of what was covered:

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Summary of Coverage

PART B - Modified Essay Questions (All 7 answered):

1. Hand Hygiene - 3 methods (soap/water, ABHR, surgical scrub), WHO 6-step technique, products with mechanisms, WHO 5 Moments
2. HAIs + CAUTI - Types, definition, etiopathogenesis (biofilm, extraluminal/intraluminal routes), risk factors, lab diagnosis (urine culture ≥10³ CFU/mL), treatment
3. VAP - Pathogenesis (3-factor model), risk factors, organisms (MDR table), lab diagnosis (BAL ≥10⁴ CFU/mL, PSB ≥10³ CFU/mL), treatment, prevention bundle
4. Sterilisation + Autoclave - Definitions, principle (moist heat under pressure), parameters (121°C/15psi/15-20min), labelled diagram, uses/advantages/disadvantages
5. Chemical Sterilants - Classification (high/intermediate/low level; gaseous), agents, mechanisms, healthcare applications
6. Biomedical Waste - Definition, BMW Rules 2016, colour-coded segregation table, all treatment/disposal methods
7. AMSP - Definition, need (resistance, cost, ADRs), CDC 7 core elements, all strategies (pre-authorization, PAF, de-escalation, monitoring)

PART C - Short Structured Questions (All 17 answered):

1. HAI definition, sources, factors, organisms
2. Modes of transmission, standard precautions, blood spill management
3. PPE types, donning and doffing steps, precautions
4. Contact-transmitted agents + infection control
5. Droplet-transmitted agents + infection control
6. Airborne agents + TB-specific infection control (administrative/environmental/personal)
7. HICC constitution and functions
8. CRBSI - complete answer
9. SSI - complete answer
10. Care bundles (CLABSI, CAUTI, VAP)
11. HAI surveillance objectives and methods
12. Plasma sterilization (STERRAD) principle and uses
13. Hot air oven functioning, uses, advantages/disadvantages
14. Spaulding's classification with examples
15. CSSD - definition, layout, zones, functions, monitoring
16. Sterilization indicators (Class 1-6 + BIs) + chemical disinfectant tests
17. OT disinfection + membrane filters 18-20. NSI agents, needle precautions, PEP (general, HIV, HBV)
18. AMSP compliance monitoring, DDD and DOT definitions
19. Escalation/de-escalation + hospital antibiogram
20. Water contamination classification, surveillance methods, Eijkman test
21. OT air quality evaluation - methods, criteria, organisms, frequency

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PART B — Modified Essay Questions

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PART C — Short Structured Questions

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