BMS 118 · Common Core (Tronc commun)Section 6.5 · Environmental, household and hospital hygiene
Section 30 of 31
Hospital hygiene and infection control
Explain how a health-care-associated infection arises, follow the chain of infection through a health facility and name its break points, and apply standard precautions, environmental cleaning, safe waste segregation and isolation precautions in the nurse’s daily work.
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Why this matters
A hospital gathers in one building the people most vulnerable to infection and the micro-organisms most resistant to treatment. Any patient admitted for one problem can acquire a second, new infection from the care itself, and the nurse’s hands, the shared equipment and the handling of waste decide whether that happens. Hospital hygiene is not decoration added to treatment: it is the difference between a place that heals and a place that spreads disease.
What you need to know first
You need the chain of infection from section 3.2 — agent, reservoir, exit, transmission, entry and susceptible host — and the everyday experience of visiting or working in a clinic. No microbiology is required: each organism will be described by the link it occupies.
Words to know (6)
Health-care-associated infection
An infection a patient acquires during care that was neither present nor incubating when they arrived; it is also called a nosocomial infection. A surgical wound that becomes infected five days after an operation is a health-care-associated infection.
Standard precautions
The basic protective measures applied to every patient at every contact, whether or not an infection is known. Hand hygiene, gloves, a gown and safe sharps disposal are standard precautions.
Personal protective equipment (PPE)
The barrier items a health worker wears — gloves, gown, mask and eye protection — chosen according to the risk of contact or splash. You wear a mask and eye protection only when a splash of blood or fluid is likely.
Sharps
Items that can cut or pierce the skin — needles, scalpels, broken glass, lancets — and can carry blood-borne infection. A used needle is a sharp and goes straight into the puncture-proof container.
Isolation precautions
Extra measures added to standard precautions for a known or suspected infection, chosen by how it spreads — contact, droplets or air. A patient with suspected pulmonary tuberculosis is placed under airborne precautions in a single room.
Health-care waste
Every waste produced during care, sorted at the point of generation into general, infectious, sharps, pharmaceutical, chemical or radioactive streams. A blood-soaked dressing is infectious waste; its outer packaging is general waste.
One idea at a timeIdea 1 / 7
In one sentence A health-care-associated infection is a new infection a patient catches from the care itself, not from the illness that brought them in.
Health-care-associated infection
Also called a nosocomial infection, it is an infection that was neither present nor incubating when the patient was admitted. In practice it is recognised when infection appears more than 48 hours after admission, or within 30 days of an operation, or within a year when a surgical implant is involved. The commonest forms are surgical site infection, catheter-associated urinary tract infection, bloodstream infection from a central line, and pneumonia in a patient on a ventilator. Hospitals concentrate risk because the patients are already fragile, because care uses invasive devices that cross the body’s defences, and because micro-organisms travel easily from patient to patient on hands, equipment and surfaces. Some of these organisms, such as meticillin-resistant Staphylococcus aureus and Clostridioides difficile, also resist many antibiotics, which makes the resulting infection harder to treat.
For example
A patient admitted for a fractured hip develops a wound infection and diarrhoea a week after surgery; neither problem was present on admission.
Pause and check yourself
A patient develops a fever 12 hours after admission. Is that a health-care-associated infection?
Show the answer
Usually not, because a health-care-associated infection was neither present nor incubating on arrival; a fever that early more often means the infection was already developing before admission or has another cause. The 48-hour rule is a practical guide, not a law.
Read detailed explanations
Five moments and two techniques: the mechanism behind the hand-hygiene rule
Why does timing matter more than scrubbing? Skin carries two populations of micro-organisms. Transient flora are acquired from patients and the environment, sit loosely on the surface, and are the organisms that cause cross-infection; resident flora live in the deeper layers, are hard to remove, and rarely cause disease except during surgery or when a device is inserted. Hand hygiene is designed to remove or kill the transient population, and an alcohol-based hand rub does this by denaturing microbial proteins and disrupting the lipid envelope of enveloped viruses, which is why a formulation of 60–80% alcohol is effective and why the same product fails against spores and against non-enveloped viruses such as norovirus. Technique is specified because it determines contact: the rub must cover every surface — palms, backs, between the fingers, thumbs, fingertips, wrists — and be rubbed until dry, which takes about 20 to 30 seconds. Soap and water work differently: the detergent lifts dirt and organisms, and friction followed by rinsing physically carries them away, so a wash lasts about 40 to 60 seconds and the hands are dried with a paper towel, because wet hands transfer organisms more efficiently. The five moments are placed where the chain is most likely to be completed: before touching a patient (protects the patient), before a clean or aseptic procedure (protects a portal of entry), after body-fluid exposure (protects the worker), after touching a patient (protects the worker and the next patient), and after touching the patient’s surroundings (protects everyone from the contaminated environment). Measured compliance in busy wards is often well below half, but it rises when rub is available at the point of care, when dermatitis is prevented with emollients, when jewellery is forbidden, and when senior staff are seen to comply — the elements of the WHO multimodal improvement strategy.
Transmission-based precautions: contact, droplet and airborne isolation in practice
Standard precautions are applied to every patient; transmission-based precautions are added when an infection is known or suspected, and their content is decided by the route the organism uses. Contact precautions are used for organisms spread by direct or indirect touch, including meticillin-resistant Staphylococcus aureus, Clostridioides difficile, carbapenemase-producing Enterobacterales and scabies. The patient is placed in a single room when possible, gloves and a gown are worn for every entry, dedicated equipment such as a stethoscope and thermometer stays in the room, and the room is cleaned daily with special attention to the toilet and the high-touch surfaces. Droplet precautions apply to organisms carried in large respiratory droplets that travel about one metre, such as influenza, meningococcal meningitis, mumps and pertussis; a surgical mask is worn within that distance, the door may remain open, and the patient wears a mask when being transported. Airborne precautions are reserved for organisms that remain suspended in the air as fine droplet nuclei and can travel far beyond a metre, and against which a surgical mask is not enough: pulmonary tuberculosis, measles, varicella and disseminated herpes zoster. A single room with the door closed is required, an airborne infection isolation room with negative pressure and a defined number of air changes per hour is preferred when available, staff who enter wear a fitted particulate respirator such as an N95 or FFP2, and only immune staff should care for measles or varicella. Cohorting — placing patients infected or colonised with the same organism together — is used when single rooms are scarce, but it must not mix patients carrying different organisms. Duration matters too: precautions continue until the organism has cleared by defined criteria, which for C. difficile may mean several days after diarrhoea stops. The nurse’s role runs through all of it: recognising the indication, requesting the right room, teaching the patient and family why the barrier is used, keeping the equipment inside, reducing unnecessary transport, and documenting the start and end of precautions so the next shift is not guessing.
Cleaning, disinfection and sterilisation: the Spalding classification and contact time
Not every item needs the same treatment, and the choice is made with a simple scheme called the Spalding classification, which sorts equipment by the body site it touches. Critical items enter sterile tissue or the vascular system — surgical instruments, implants, biopsy forceps, needles — and must be sterile, which in practice means steam sterilisation in an autoclave at the specified temperature, pressure and holding time. Semicritical items contact mucous membranes or non-intact skin without entering sterile tissue — endoscopes, laryngoscopes, respiratory tubing, vaginal speculae — and require at least high-level disinfection, which destroys all micro-organisms except a high concentration of bacterial spores. Non-critical items touch intact skin only — blood-pressure cuffs, stethoscopes, bed rails, crutches — and need low-level disinfection or, often, cleaning alone. Two rules decide whether the process actually works. The first is that cleaning must precede disinfection or sterilisation, because organic material raises the organic load, and a high load consumes the active chemical or shelters the organism inside a biofilm, so the measured concentration no longer matches the contact time. The second is to follow the manufacturer’s instructions exactly: concentration, temperature, contact time and the compatibility of the agent with the material are all specified, and shortening the time or diluting the product invalidates the result. Glutaraldehyde 2% illustrates the arithmetic: about 20 minutes is used for high-level disinfection, while chemical sterilisation requires several hours, commonly three to twelve. Some agents are chosen for the organisms they must defeat: chlorine-releasing products are used for spills and for surfaces contaminated with C. difficile spores or norovirus, and alcohol is avoided on those surfaces. Prions, the infectious proteins responsible for Creutzfeldt-Jakob disease, resist conventional sterilisation and require single-use instruments and specific national protocols. Environmental cleaning has its own schedule: routine surfaces at least daily and after each patient, terminal cleaning when a patient is discharged, and shared equipment cleaned between every patient use, with colour-coded cloths and mops so that the clean area is not recontaminated by the dirty one.
Explore the diagram
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The chain of infection inside a health facility
The six links of the chain mapped onto a hospital, with the break points the nurse controls: hand hygiene, standard precautions, cleaning and disinfection, safe sharps and waste handling, and isolation of the susceptible patient.
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01 / 4The six links mapped onto the hospital
If the drawing is wider than this panel, scroll it sideways. Labels stay readable; the numbered explanations below show the same ideas.
The six links mapped onto the hospital
In a facility the reservoir is often another colonised patient, a contaminated surface or shared equipment such as a stethoscope, and the susceptible host is the patient, made fragile by illness, surgery, age or immunosuppression. The portal of entry is usually a device that bypasses the skin — a catheter, an intravenous line or a surgical incision.
Schematic teaching plate, not to scale. It maps the six links of the chain of infection onto a health facility and shows where nursing measures break them; the named organisms and diseases are examples of each link, not a complete list.
Key points to remember
✓A health-care-associated infection is acquired during care and is usually recognised more than 48 hours after admission.
✓In hospital the reservoir is often another patient, the environment or shared equipment, and the susceptible host is the patient.
✓Hand hygiene at the WHO five moments is the single most effective measure; alcohol rub for routine care, soap and water for visible dirt and spores.
✓Standard precautions apply to every patient; gloves, gown, mask and eye protection are chosen by task, and gloves never replace hand hygiene.
✓Never recap a needle: dispose of it uncapped at the point of use, and sort waste into general, infectious, sharps, pharmaceutical, chemical and radioactive streams.
Go deeper
Worked example
Tracing a hospital-acquired infection to its break points. A 74-year-old patient is admitted with a stroke and a urinary catheter is inserted. On the fifth day she develops a fever, cloudy urine and confusion. The ward team must decide whether this is a health-care-associated infection, and where the chain should have been broken.
First confirm the infection is health-care-associated. The fever began on day five, far more than 48 hours after admission, no urinary infection was documented on arrival, and a urinary catheter is in place. A catheter-associated urinary tract infection is the working diagnosis until another cause is found.
Identify the agent and the reservoir. The organism comes either from the patient’s own perineal flora, carried into the bladder by the catheter, or from the hands of a carer. The drainage bag, the tubing, the tap and the measuring jug are all environmental reservoirs.
Name the route and the open links. Contact transmission along hands and equipment, and the portal of entry created by the catheter, are the links that were left open. The nurse should be able to say which link each measure closes.
Close the links from now on. Hand hygiene at the five moments, aseptic technique at insertion and whenever the closed system is opened, drainage kept below bladder level, gloves to handle the bag, and daily review of whether the catheter is still necessary.
Extend to the environment and to waste. Clean and disinfect the trolley, the jug and the bed rails between patients, and dispose of used gloves and the drainage bag as infectious waste. If a urine sample is taken, the needle is never recapped.
The infection did not appear by chance: a device and a pair of hands completed a chain. The response is not one heroic clean but the consistent closure of several links — hand hygiene, aseptic device care, environmental cleaning and correct waste disposal — for every patient, every time.
Common misconception
The most common wrong model is that infection control means wearing gloves. Gloves protect the wearer’s hands from contact with body fluids, but they are not sterile, they are not a substitute for hand hygiene, and a contaminated gloved hand carries organisms to the next patient exactly as a bare hand does. Wearing gloves for a whole round of care, or washing and reusing them, makes transmission more likely, not less.
Check your reasoning
Think of a care procedure you have seen or performed — a dressing, an injection, a catheter. Trace the six links for that procedure and choose one standard precaution that would break the link you judge most fragile.
Reveal an answer
For a dressing change the agent is often Staphylococcus aureus from the patient’s own skin; the reservoir is the wound and the surrounding skin; the portal of exit is the wound discharge; transmission is by contact on hands and instruments; the portal of entry is the open wound itself; and the host is the patient, whose wound and nutrition decide resistance. The most fragile link is usually transmission, so hand hygiene and clean or sterile instruments close it; if the wound is already colonised, protecting the portal of entry with aseptic technique and an intact dressing matters most.
Where this comes from
BMS 118 Hygiene and Sanitation lecture notes (supplied) · Methods and types of proper hygiene and sanitation — cleaning, disinfection, high-level disinfection and the chemical sterilant exposure times of three to twelve hours, lines 250–268; environmental hygiene and infection control in health-care settings, lines 478–489.
Beyond the supplied notes: standard WHO-aligned infection-control practice · The supplied notes do not cover hospital infection control directly. Health-care-associated (nosocomial) infection, the chain of infection inside a facility, the WHO five moments for hand hygiene, standard precautions and personal protective equipment, sharps safety and recapping, health-care-waste segregation and transmission-based isolation precautions are drawn from standard, uncontroversial WHO-aligned infection prevention and control guidance; the same guidance treats prions as agents that resist conventional sterilisation and require single-use instruments and specific national protocols.
WHO — Infection prevention and control · Standard precautions, the multimodal hand-hygiene improvement strategy, the five moments for hand hygiene and transmission-based precautions.
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About this course and its sources
Bilingual lessons organised from the supplied BMS 118 Hygiene and Sanitation lecture notes (Mme Vusheng Vera & Mr Nfor Clauvis). Diagrams are original educational schematics; sections that go beyond the supplied notes say so in their sources. Nursing and French-language review are pending.