Microbiology SC036: Protect Yourself And Your Patients: Infection Control

Question 1

Alcohol-based hand rub

Answer 1

WHO formulation:
1.
Ethanol 80% v/v (2 carbon: better virucidal activity)
Glycerol 1.45% v/v
Hydrogen peroxide 0.125% v/v (kill bacteria spore)

2.
Isopropyl alcohol 75% v/v (3 carbon: better bactericidal activity)
Glycerol 1.45% v/v
Hydrogen peroxide 0.125% v/v (kill bacteria spore)

Question 2

Descending order of resistance to germicidal chemicals

Answer 2

Prion
—> Bacterial spores
—> Protozoan oocysts
—> Mycobacteria (Alcohol can kill from here downwards)
—> Non-enveloped viruses (e.g. norovirus, rotavirus)
—> Fungi
—> Vegetative bacteria
—> Enveloped viruses

Question 3

Time course of efficacy of unmediated soap / water and alcohol-based handrub in reducing hand contamination

Answer 3

Alcohol:
- 15 sec: 3 log reduction in bacterial contamination (3ml of alcohol enough (one palmful))

Unmediated soap + water:
- 15 sec: 1 log reduction

Question 4

6 moments for hand hygiene

Answer 4

Protect patient:

1. Before touching a patient
2. Before clean / aseptic procedure

Protect yourself:

3. After body fluid exposure risk
4. After touching a patient
5. After touch patient surroundings
6. Before touching your mucous membranes

Question 5

Exit + Entry control (出入口管制)

Answer 5

Entry control:
1. Direct observed hand hygiene (DOHH) before taking meals / drugs

Exit control:

2. Personal hygiene in toilet
   - wipe toilet seat lid with tissue sprayed with disinfectant
   - wash hands with soap + water, then rub hands with alcohol handrub

Question 6

7 steps of hand hygiene

Answer 6

1. Palm to palm
2. Palm to back
3. Finger interlaced
4. Back of finger
5. Thumb
6. Finger tips
   (7. Wrist)

Question 7

Standard precautions

Answer 7

1. Wear gloves
   - when handling blood, body fluids, secretions, mucous membrane / non-intact skin
2. Wear a mask, protective eyewear and a gown
   - to protect from splashed blood / body fluids
3. No recapping of needle
4. Handle sharps carefully
5. Perform hand hygiene immediately
   - after taking off gloves / handling blood, body fluids, secretions, mucous membrane / non-intact skin

Question 8

Transmission-based precautions

Answer 8

1. Contact precaution (Gloves + PPE + Handwashing; Patient placement: Single / Cohort; Dedicated equipment)
   - Viral haemorrhagic infections
   - Viral haemorrhagic conjunctivitis
   - Skin infections of highly contagious
   - Respiratory: RSV, Parainflueza, Enterovirus
   - GI: Norovirus, Rotavirus, Clostridium difficile infection
   - Colonisation with MDR bacteria
2. Droplet precaution (Surgical mask + Handwashing; Patient placement: Single / Cohort)
   - Influenza
   - Adenovirus
   - Parvovirus B19
   - Mumps, Rubella
   - Pertussis
   - Mycoplasma pneumonia
   - Invasive N. meningitidis
   - Invasive H. influenzae type b
   - Streptoccocal pharyngitis
   - Diphtheria (pharyngeal)
   - Pneumonic plague
3. Airborne precaution (Wear respirator)
   - TB
   - Varicella zoster
   - Measles
   (- Highly pathogenic virus: Avian influenza, SARS, COVID-19)

Airborne Patient placement:

• 12 air exchanges / hour for new construction / renovation
• 6 air exchanges / hour for existing facilities
• Air exhausted directly to the outside / recirculated through HEPA filtration

(4. Isolation precaution
- Influenza A H7N9
- MERS
- Standard + Contact + Droplet + Airborne)

Question 9

Repeat of N95 respirator fit test

Answer 9

1. Sigfinciant increase / decrease in weight (10%)
2. Change in facial structure / scarring due to dental work, cosmetic surgery / accidents
3. When no supply of appropriate model / size of respirator
4. Any other condition that may interfere with face sealing

Question 10

Prevention blood-borne pathogens transmission

Answer 10

Mode of transmission:

1. Percutaneous
2. Mucous membrane
3. Non-intact skin

Standard precaution:
- ∵ Potential for infectivity of any patient’s blood / body fluids cannot be known

Prevention of exposure to blood borne pathogens:

1. Appropriate barrier precaution
   - Gloves for any invasive procedure involving needle (venipuncture, phlebotomy, suturing)
   - Change gloves between patient
   - Perform HH after gloves removed
   - Goggle, mask, protective gown when splashing is likely
   - Cover wound with waterproof dressing before caring of patients
2. Careful handling of sharps
   - Gloves
   - Vacuum system
   - Blue tray with small sharp box
   - Retractable lancet
   - No recapping / One hand scoop technique / Safety device
   - Sterile disposable safety scalpel

Procedures following sharps injury:

• Do not press on wound + Rinse off blood
  1. Apply first aid on site
  2. Report to ward in-charge
  3. Attend staff clinic / A+E for blood screening and treatment (PEP) as required and complete incident report form —> HBV, HCV, HIV serology
  4. Send blood from source patient for HBsAg, HCV, HIV with consent
  5. Report “Injury on duty” to Human Resources via AIRS

Post-exposure prophylaxis:
HBV post exposure:
- Responder to 3 doses of vaccine: No treatment
- Non-responder: HBIG

HIV: Chemoprophylaxis after assessment
- most effective within 2 hours post exposure

Free vaccination of Immune status inventory:

1. Hep B
2. MMR
3. Chickenpox
4. Influenza A + B