Level 2 of 6Must-remember

Infection control and occupational exposure

Assess, manage and stay safe — enough on its own

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The card — assess, manage, caution

Assessment— look, ask, measure

Ask the containment question before the diagnostic one: when evaluating a patient with a suspected infectious disease you must decide what infection control methods are needed to prevent transmission to other people, and because confirmation takes days, precautions are selected by *syndrome* at the door and de-escalated later, never the other way round.
The four syndromic groupings that capture nearly all transmissible presentations: fever with cough, sore throat or breathlessness; diarrhoea or vomiting; fever with a rash or vesicles; and fever with an epidemiological trigger.
The epidemiological trigger, asked of every febrile patient: travel or contact with a case or outbreak within 21 days; hospitalisation, surgery, dialysis or long-term care within 90 days; or known carriage of a resistant organism.
Decide whether the infection is health care–associated: infections arising within the first 48–72 hours of admission are community-acquired (or attributed to the transferring institution), while those arising thereafter are health care–associated or nosocomial — a nosocomial infection is assumed potentially resistant.
Presentation is often blunted: fever may be absent in the elderly, the malnourished, those on corticosteroids and the critically ill; in the elderly non-specific decline — confusion, falls, immobility, anorexia — is the commonest presentation of infection.
Hunt the pathogen-level red flags actively: fever with travel from a viral haemorrhagic fever area within 21 days, contact with a VHF case or their samples, or organ failure or haemorrhage — treat as high risk of VHF, strict containment, no further phlebotomy until agreed, no aerosol-generating procedures.
Tuberculosis: cough for over 2–3 weeks, weight loss, night sweats, haemoptysis, upper-zone radiographic change or HIV — airborne precautions, because early identification, isolation and testing are the critical steps in tuberculosis control.
The other containment-before-diagnosis flags: measles (fever, coryza, conjunctivitis, cough, Koplik spots); a vesicular rash or zoster crossing three or more dermatomes; membranous pharyngitis with a bull neck (diphtheria); fever with haemoptysis, buboes or rodent or flea exposure (pneumonic plague); and fever with severe respiratory illness plus epidemiological risk (novel influenza A H5/H7, MERS-CoV).
Diarrhoea: *Clostridioides difficile* is considered when there are three or more unformed stools in 24 hours without an alternative explanation and the patient is not on laxatives; norovirus gives explosive vomiting, a short incubation and clusters among patients and staff.
After a sharps injury or splash, grade the exposure at the time — higher risk is percutaneous injury, a hollow-bore needle especially from artery or vein, deep injury and visible blood on the device; lower risk is contact with intact skin (negligible) and a superficial scratch from a solid needle through gloves.
Grade the fluid: blood, semen, vaginal or rectal fluid, breast milk, CSF and other serous fluids, or any visibly bloodstained fluid are high risk; faeces, urine, gastric and respiratory secretions, saliva and sweat not contaminated with blood carry an exceedingly low risk.
Grade the source: advanced untreated HIV, a high viral load or hepatitis B e antigen positivity raise the risk, whereas a source on effective treatment with an undetectable viral load makes HIV risk negligible.
Know the three numbers that anchor the conversation with an injured colleague — risk of transmission from a single percutaneous injury: hepatitis B 6–30% (highest when the source is hepatitis B e antigen positive), hepatitis C 1–3%, HIV 0.3%.
Know your own anti-HBs titre before you need it: anti-HBs of 10 mIU/mL or more indicates protection; staff are tested 1–2 months after the last vaccine dose and reimmunised if the level is below 10 mIU/mL.
Watch for seroconversion illness in an exposed worker: fever, maculopapular rash, pharyngitis, lymphadenopathy and mucosal ulceration 2–6 weeks after exposure suggests acute HIV; malaise, anorexia and jaundice suggest acute hepatitis B; acute hepatitis C is more often silent.
The exposure is an event, not a symptom, and its most important feature is that it is frequently concealed — ask directly, because the determinants of a bad outcome are administrative (concealment, no baseline sample, delay past the window, loss to follow-up) rather than biological.

Management— do this, in order

Hand hygiene, the WHO Five Moments: before and after all patient contacts, including before and after aseptic procedures and after contact with body fluids and the patient environment — either wash for 20 seconds with soap and warm water or clean with an alcohol-based hand rub.
Alcohol rub is the default, but soap and water is mandatory when hands are visibly soiled and whenever patients are vomiting or have diarrhoea, even if gloves were used — alcohol gel does not kill *C. difficile* spores and poorly inactivates norovirus, a non-enveloped virus.
Personal protective equipment: gloves for all invasive procedures including venesection and for contact with sterile sites, mucous membranes, body fluids or non-intact skin; a plastic apron where clothing or skin may be contaminated; a surgical gown where contamination may be extensive; eye protection wherever blood or body fluid may splash.
Respiratory protection: fit-tested particulate respirators (N95 respirators, so called because they filter 95% of airborne particles) for infectious tuberculosis and for high-consequence respiratory pathogens such as avian influenza and MERS; for aerosol-generating procedures WHO recommends a fit-tested N95 mask, gown, gloves and a face shield or goggles.
Source control: put a surgical mask on the coughing patient — the highest-yield single intervention available; hand hygiene and surgical facemasks appear to prevent household transmission of influenza when implemented within 36 hours of symptom recognition in an index patient.
Contact precautions (*C. difficile*, norovirus, undiagnosed diarrhoea, MRSA, VRE, ESBL and carbapenem-resistant organisms, *Candida auris*, scabies, draining wounds): gown and gloves on entry, dedicated equipment, ideally a single room with en-suite toilet, and bleach (sporicidal) cleaning for *C. difficile* and norovirus.
Droplet precautions (influenza and most respiratory viruses, meningococcal disease, pertussis, diphtheria, mumps, rubella, pneumonic plague): gown, gloves, eye protection and a mask or respirator, with a surgical mask on the patient.
Airborne precautions (tuberculosis, measles, varicella, disseminated zoster, COVID-19 and novel respiratory pathogens): a fit-tested respirator for every entrant and a negative-pressure room with a minimum of 12 air changes per hour, exhausting directly outside or through a HEPA filter — varicella and SARS-CoV-2 need contact AND airborne precautions.
When isolation facilities are scarce: risk-assess, house the highest-risk patients in the facilities available, apply basic precautions even where no side room exists, and consider cohort isolation — patients with the same *microbiologically confirmed* infection on the same ward.
Sharps discipline: bring the container to the point of use before the needle is opened, do not resheath needles, do not pass sharps hand to hand, and let the user dispose of the sharp.
Needlestick first aid, immediately: encourage bleeding gently under running water without scrubbing, squeezing hard or sucking, then wash with soap and running water; for a mucous membrane splash irrigate copiously with water or 0.9% sodium chloride, removing contact lenses first and then discarding them; record the time.
Take baseline bloods from the exposed person BEFORE any prophylaxis: HIV antibody/antigen, anti-HBs and HBsAg, hepatitis C antibody, and — if antiretrovirals are to be prescribed — full blood count, renal and liver function, plus a pregnancy test to inform regimen choice.Not available at your setup — Renal function (creatinine/urea), Liver function tests.
Hepatitis B is the most transmissible and most preventable, so address it first: if the exposed person has documented anti-HBs of 10 mIU/mL or more, no prophylaxis is needed; if unvaccinated, incompletely vaccinated or of unknown status, give HBIG plus a full vaccine course at separate sites with separate syringes.Doctor / Nurse
Hepatitis B doses: HBIG 500 IU IM in adults (or 0.06 mL/kg of the alternative preparation; neonatal dose commonly 200 IU IM), ideally within 24 hours and effective up to 7 days from exposure; hepatitis B vaccine 1 mL (20 micrograms) IM into the deltoid in adults and 0.5 mL (10 micrograms) IM in children under 16 years, into the anterolateral thigh under 2 years.Doctor / Nurse
HIV post-exposure prophylaxis must be started within 72 hours and has diminishing efficacy the longer initiation is delayed — give the first dose at once rather than deferring it pending source testing: tenofovir disoproxil fumarate 300 mg plus lamivudine 300 mg (or emtricitabine 200 mg) once daily plus dolutegravir 50 mg once daily, for 28 days.Doctor / Nurse
Paediatric HIV prophylaxis (under 25 kg or unable to swallow tablets): zidovudine 4 mg/kg (maximum 300 mg) orally 12-hourly plus lamivudine 4 mg/kg (maximum 150 mg) orally 12-hourly, with dolutegravir 50 mg once daily as the third agent if 20 kg or more and able to swallow tablets, otherwise a weight-band dispersible formulation; a child of 25 kg or more able to swallow tablets may take the adult regimen.Doctor / Nurse
Support adherence: if only a two-drug backbone is obtainable immediately, start it and add the third agent within 24 hours, and supply an antiemetic — metoclopramide 10 mg orally 8-hourly as required, or ondansetron 4–8 mg orally 8-hourly as required — because nausea, headache, diarrhoea and fatigue are the usual reasons for abandonment.Doctor / Nurse
Finish the package: tetanus booster if the primary course was completed but no booster given in the past 5 years (those with an incomplete primary course are immunised and also receive tetanus immune globulin); hepatitis C has no prophylaxis so surveillance is the intervention; and arrange serial serology for HIV, hepatitis B and hepatitis C at 6 weeks and 3 months, with hepatitis C and HIV again at 6 months if the exposed person is immune to hepatitis B or received immune globulin.Doctor / Nurse

Caution— what harms

Never wait for a laboratory result before isolating: precautions are chosen by syndrome and de-escalated later; a positive screening swab means colonisation, and the response is isolation and hand hygiene, not systemic antibiotics.
Never rely on alcohol hand rub for *C. difficile* or norovirus: spores are not killed by alcohol-based gel or standard hospital cleaners, so hands must be washed mechanically with soap and water and the room cleaned with a sporicidal (bleach) agent.
Gloves are not a substitute for hand hygiene, and an unfit-checked respirator leaks — facial hair defeats the seal, doffing is where most self-contamination occurs, and the respirator comes off last and outside the room.
Never cohort a suspected case with a confirmed one: cohorting requires confirmed identity of the organism, or you infect the patient who did not have it.
Do not treat asymptomatic bacteriuria: apart from pregnant patients, most others need not undergo urine culture or treatment, and in the elderly bacteriuria frequently coexists with confusion that is not related to it — do not collect urine from the drainage bag or a long-standing catheter.
Do not test stool for *C. difficile* without three or more unformed stools in 24 hours and no alternative explanation, never while on laxatives; use a two-step algorithm including toxin detection because PCR alone detects carriage; there is no utility in a test of cure, and avoid repeat testing within 7 days of a negative or 14 days of a positive result.
A positive respiratory viral test may direct isolation but does not necessarily reduce the need for antibacterial therapy, since bacterial coinfection occurs; and unexpected organisms from sites with complex flora may represent colonisation or contamination, so evaluate cultures critically before abandoning best-guess therapy.
Never let stewardship delay antibiotics in sepsis — take blood cultures before antibiotics, but give the antibiotics.Not available at your setup — Blood culture.
Never give hepatitis B vaccine into the buttock, where immunogenicity is reduced; give it into the deltoid (anterolateral thigh under 2 years).Doctor / Nurse
Never delay the first dose of HIV prophylaxis waiting for the source result; if the source refuses, cannot consent, or the result will not arrive within the prophylaxis window, presume the source positive for the purpose of starting prophylaxis.Doctor / Nurse
Never test the source without informed consent, and the injured person must not be the one who takes it — testing without consent is not permissible.
A negative hepatitis C antibody at four weeks means nothing: after an acute exposure HCV RNA is detectable within 2–4 weeks but antibodies may take 6–12 weeks to appear, and the HIV antibody window is prolonged when post-exposure prophylaxis has been used.
Do not apply bleach, alcohol or caustic agents to the wound, and do not scrub, squeeze hard or suck it.
Do not omit the baseline sample: without it a positive result at three months proves nothing, and the exposure cannot be attributed to work; concealment of the injury, a missing baseline, delay past the window and loss to follow-up are the four determinants of a bad outcome.
Maintain confidentiality: hepatitis, HIV and tuberculosis carry social stigma, confidentiality about the diagnosis is maintained at all times, and is broken only when there is an overwhelming individual or public health risk — a statutory notification is a lawful disclosure, a corridor conversation is not.

Refer / escalate

Escalate immediately for suspected viral haemorrhagic fever (strict containment, no further phlebotomy until agreed, no aerosol-generating procedures, transfer to a BSL-4 capable centre, and treat patient samples as extreme biohazard risks), for suspected novel influenza A, MERS-CoV or other high-consequence respiratory pathogen, and notify the public health authority on clinical suspicion rather than on confirmation; for occupational exposure, contact the occupational health or on-call service the same shift so that HIV prophylaxis starts within 72 hours and hepatitis B immune globulin within 24 hours, and always alert a receiving facility about infection control issues before transferring a patient.

The card — assess, manage, caution

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