Infection Control

Risk of infection

• Depends upon:
  • Route of exposure
  • Concentration of pathogen
  • Infectious virility of pathogen
  • Volume (dose) of infectious material
  • Immunocompetence of exposed individual

Exposure classification (QLD HEALTH)

• Exposure
  • Injection of >1mL of body fluid
  • Parenteral exposure to lab specimens containing high titre of virus
  • Any skin penetrating injury
  • Mucous membrane exposure to blood
  • Human bite or scratch with blood exposure
  • Prior (not fresh) wound or skin lesion contamined with body fluid
• Doubtful exposure
  • Intradermal injury with needle not thought to be contaminated with body fluid
  • Superficial wound without visible bleeding by instrument not thought to be contaminated with body fluid
  • Prior wound or skin lesion contaminated with non-blood body fluid e.g. urine
  • Human bite with no blood exposure e.g. saliva
• Non-exposure
  • Intact skin visibly contaminated with blood or body fluid
  • Needlestick with non-contaminated sharp

Risk of transmission after exposure to blood

Management of potential exposure to HBV/HCV/HIV

• Expedite triage
• Irrigate exposed areas with soap and water
• Hx: Circumstances, source patient and vaccination history of exposed person
  • Type of exposure, type and amount of tissue
  • HPV vaccination and antibody titres
  • HIV Ab, HIV Ag, HBsAb and HCV Ab (+ HBsAg if high risk of HepB transmission)
• Obtain blood samples from exposed person + hCG in women
• Obtain blood samples from source patient if known (with consent and counselling)
  • HBsAg, HCV antibody, HIV antibody (if positive, need viral loads)
  • Consider rapid antigen HIV point of care testing of source to guide PEP if HIV status of source is unknown or the source is assessed as being at risk for HIV
• Determine need for tetanus
• Determine need for HepB PEP
• Determine need for HIV PEP
• Counsel exposed person re: risk of transmission and risks/benefits of PEP
• Arrange follow-up

Management of potential exposure to HBV/HCV/HIV

• HBV
  • Every unvaccinated healthcare worker exposed needs HepB vaccination course
  • Additionally, if source is HBsAg positive, need HBIG x 1
  • If previously vaccinated and known responder – No intervention required
  • If previously vaccinated but non-responder – HBIG x 1 and initiate revaccination unless source HBsAg negative
  • If previously vaccinated but antibody response unknown
    • Test exposed person for anti-HBs
      • If adequate, no treatment
      • If inadequate and source HBsAg Positive – HBIG x 1 and vaccine booster
      • If inadequate and source unknown – Vaccine booster and re-check titre in 1-2 months

Management of potential exposure

• HCV
  • Anti-HCV testing of source patient
  • ALT and HCV RNA of exposed patient and follow-up at 4-6 months (can do at 4-6 weeks if earlier diagnosis desired)
  • Medical personnel exposed to HBV or HCV-infected blood do NOT need to take precautions against secondary transmission during follow-up period but should NOT donate blood, plasma, tissue or semen
• HIV
  • If source is HIV positive, determine CD 4 count, HIV viral load and current/previous ART with history of resistance and prognosis as this helps determine PEP regime
  • If source HIV negative, no further intervention required unless high situational risk of transmission or likely that source was in window period (then re-test at 12 weeks for HCV and HIV +- HBV if not immune)

Management of potential exposure

Management of potential exposure to hiv

• HIV Class I
  • Asymptomatic HIV infection or known viral load <1500 RNA copies/mL
• HIV Class 2
  • Symptomatic, AIDS, acute seroconversion or known high viral load
• If known drug resistance in source patient, get expert advice on PEP regime
• PEP most beneficial <36 hours from exposure but should still be started if presents after this (ideally <2 hours)
• Optimal duration is thought to be 4 weeks
• Can stop PEP if source confirmed HIV negative

Management of potential hiv exposure

• PEP toxicity
  • 50% of patients on PEP stop due to side effects
  • Need monitoring at baseline and at 2 weeks with FBC, U&E and LFT
• Perform HIV antibody testing for at least 6 months post-exposure
• Healthcare workers with potential HIV exposure must prevent secondary transmission for 6- 12 months by:
  • Condoms or sexual abstinence, do not donate blood, plasma, tissue or semen, avoid breastfeeding
  • Advise to seek medical attention for any acute illness in follow-up oeriod as may be acute seroconversion illness
  • Do not need to change care of other patients based purely on exposure

Management of potential exposure

• Basic 2-drug regime
  • Zidovudine + Lamivudine
  • Zidovudine + Emtricitabine
  • Tenofovir + Lamivudine
  • Tenofovir + Emtricitabine (Truvada)
  • Lamivudine + Stavudine
  • Emtricitabine + Stavudine
• Expanded 3-drug regime
  • Above + Raltegravir ( Truvada + Isentress)

Drugs used in PEP

• Zidovudine – Neutropaenia, anaemia, nausea, fatigue, malaise, headache, insomnia, myositis
• Lamuvidine – Headache, abdominal pain, diarrhoea, pancreatitis
• Zidovudine + Lamivudine – Toxicity equal to zidovudine alone
• Indinavir – Nephrolithiasis, crystalluria, haematuria, transaminitis, drug interactions
• Tenofovir – Asthnesia, headache, diarrhoea, nausea, diarrhoea
• Emtricitabine – Lactic acidosis with hepatic steatosis (rare)
• Stavudine – Peripheral neuropathy, pancreatitis, lipodystrophy, rapidly progressive ascending neuromuscular weakness
• Lopinavir/ritonavir – GI upset, asthenia, transaminitis, hyperglycaemia, dyslipidaemia, bleeding

Pep counselling

• Risk of HIV exposure
• Risk of seroconversion despite PEP
• Side effects of PEP
• Use of PEP in pregnancy/breastfeeding
• Risk of infecting others despite PEP
• Appropriate referral

Infection control

• Administrative controls
  • Organise, define and direct infection control activities with written infection control plan
• Equipment engineering
  • Serves to reduce risk of exposure
  • E.g. self-sheathing needles, needless drug delivery devices, sharps containers, disposable equipment, syringe splash guards, PPE
• PPE
  • Specialised clothing or devices that “does not permit blood or potentially infectious substances to pass through or reach worker clothing, skin, eyes, mouth or other mucous membranes”

Infection control

• Work practice controls
  • Modify the performance of a task to minimise exposure
  • Need policies concerning sharps disposal, recapping, disposal of contaminated linens, clothing and infectious waste, disinfection techniques for reusable equipment and restriction of employee activities in work areas e.g. eating/drinking/smoking/makeup application
• Education of the workforce
• Medical management practices
  • Pre-exposure vaccinations, acute post-exposure medical evaluation, infectious disease counselling, disease counselling and medical testing/referral

Airborne precautions

• Utilised for patients known or suspected of being infected with airborne pathogens
• Includes measles, varicella, TB
• Require isolation room, negative pressure, 6-12 air changes per hour, patient must remain in room with door closed
• If movement of patient is unavoidable, patient should wear respiratory protection
• Healthcare workers entering room must wear approved particulate respirators

Droplet precautions

• For patients known or suspected to have serious illnesses transmitted by large droplets (>5micrometres) that can be generated through talking, sneezing, coughing or performance of procedures
• Includes invasive Hib, invasive meningococcus, serious bacterial respiratory infection (Diphtheria, Mycoplasma, Pertussis, Pneumonic plague, Streptococcus pharyngitis/pneumonia/Scarlet fever and serious viral infections including adenovirus, influenza, mumps, parvovirus B19 and rubella
• Private room isolation if possible, do not need negative pressure or door closed, at least 1m between patient and other patients or visitors and patient should don a mask if not in private room
• HCW should wear face masks if within 1m of patient (N95 filtering respirator)

Contact precautions

• For patients known or suspected to have serious illness spread by direct contact with patient or items in their environment
• Includes MDR colonisation, enteric infections with low infective dose or prolonged environmental survival (C. difficile, E. coli 0157:H7, Shigella, HepA, Rotavirus, RSV, Parainfluenza, Enteroviral, HSV, Impetigo, cellulitis, scabies, staphylococcal furunculosis, herpes zoster, viral haemorrhagic conjunctivitis, viral haemorrhagic infections (Ebola, Lassa, Marburg)
• Dedicate equipment to single patient
• Clean stethoscopes before and after each patient
• Single use bathroom

TB EXPOSURE

• Transmission via inhalation of aerosolised bacilli. Only need 1-10 bacilli for infection but only 20% of exposed individuals become infected
• Standard and airborne precautions required
• Patients at high risk of TB (immigrants from high-prevalence countries, HIV, prisoners, prison staff, homeless, alcoholics, IVDU and nursing home patients) with symptoms consist with TB all need isolation
• Generally need prolonged exposure to active pulmonary TB cases for transmission but may be involved in contact tracing

Measles exposure

• Primary transmission is from person-to-person by large respiratory droplets
• Airborne transmission by aerosolised droplet nuclei has been documented in confined areas
• Need to isolate in negative pressure room with standard, contact, droplet and airborne precautions
• In the event of no prior immunity, measles immunisation as PEP can prevent disease and provides permanent subsequent protection
• IG can be used within 7 days

Mumps exposure

• Standard and droplet precautions (not airborne)
• Post-exposure IG not effective but should ensure vaccination up to date

Varicella exposure

• Transmission via respiratory droplet as well as direct contact with infected secretions from wounds
• Standard, airborne and contact precautions required
• If no evidence of immunity, HCW should receive vaccination (PEP vaccine may prevent disease too)
• VZIG within 96 hours of exposure may reduce or prevent clinical varicella in non-immune individuals
  • Indicated if prolonged direct contact and no evidence of immunity
• HCW exposed and not immune are potentially infectious from day 10-21 following exposure and should be kept away from work over that period (despite VZIG/Varicella vaccination)

Influenza exposure

• Aerosolised or droplet spread
• Recommend N95 masks for all HCW in close contact with patients
• Standard, airborne and contact precautions recommended
• Vaccination most effective if given within 2-4 months of exposure
• Chemoprophylaxis with Oseltamivir can be considered in HCW exposed to influenza

Meningococcal exposure

• Only high-risk exposures such as mouth-to-mouth, intubation or suctioning of patient while unprotected by face mask warrants chemoprophylaxis
• Family in household for 24 hours or 4 hours continuously with patient
• Chemoprophylaxis should only be given after case confirmed
• Rifampicin 600mg every 12 hours for 2 days OR ciprofloxacin 500mg single dose
• Vaccination is best prevention

Last Updated on October 2, 2020 by Andrew Crofton