Healthcare-associated infections (HAIs) affect roughly 1 in 31 hospitalized patients in the United States on any given day and contribute to approximately 98,000 preventable deaths per year, according to the CDC. Nurses are the primary line of defense: you implement precautions, enforce hand hygiene, don and doff PPE correctly, and educate patients and families every shift. Infection control knowledge is not optional background information — it is an active clinical skill tested on NCLEX, evaluated by Joint Commission, and directly tied to patient survival.
This reference covers every tier of the CDC precaution hierarchy: standard precautions that apply to all patients, and the three categories of transmission-based precautions used when standard precautions alone are insufficient. It includes PPE selection tables, the hand hygiene algorithm, the critical C. diff and norovirus exception to alcohol-based hand rub, and focused NCLEX tips on the most-tested confusions. Use alongside the MRSA nursing reference, C. diff nursing reference, and tuberculosis nursing reference for disease-specific detail.
Types of isolation precautions at a glance
| Precaution type | Transmission route | PPE required | Room type | Example pathogens |
|---|---|---|---|---|
| Standard | Any patient, any setting | Gloves, gown, mask/eye protection as indicated by task | Any | Applies universally |
| Contact | Direct or indirect contact with patient or environment | Gloves + gown on room entry | Single room preferred; cohorting acceptable | MRSA, C. diff, VRE, norovirus, scabies |
| Droplet | Respiratory droplets >5 microns; travel ≤3–6 feet | Surgical mask within 3 feet (6 feet for influenza, COVID-19 standard care) | Single room preferred; door may remain open | Influenza, pertussis, meningitis, rubella, mumps |
| Airborne | Droplet nuclei ≤5 microns; remain suspended in air | N95 respirator (or higher); eye protection for some procedures | Airborne infection isolation room (AIIR) — negative pressure, ≥6 air changes/hour | TB, measles, varicella, COVID-19 (AGPs) |
Standard precautions: the foundation of infection control
Standard precautions are the baseline tier of CDC infection control guidance, established by the Healthcare Infection Control Practices Advisory Committee (HICPAC). They apply to every patient, every encounter, regardless of diagnosis or perceived infection risk. This is the single most important concept in infection control nursing — standard precautions are not triggered by a positive test result. They are the default.
Standard precautions treat blood, all body fluids (except sweat), non-intact skin, and mucous membranes as potentially infectious for bloodborne pathogens and other microorganisms. The OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030) provides the regulatory framework governing exposure risk to HIV, hepatitis B, and hepatitis C.
Components of standard precautions
Hand hygiene is the single most effective infection control intervention. See the dedicated section below for full detail on timing and product selection.
Personal protective equipment (PPE): Selection is task-based. Gloves are worn whenever contact with blood, body fluids, mucous membranes, or non-intact skin is anticipated. Gowns are worn when clothing or skin contamination with blood or body fluids is likely (wound irrigation, suctioning, surgical procedures). Masks and eye protection (face shield or goggles) are worn when splash or spray of blood or body fluids to the face is possible.
Respiratory hygiene and cough etiquette: Covers the mouth and nose when coughing or sneezing, uses tissues followed by hand hygiene, and offers masks to symptomatic patients in waiting areas. This element of standard precautions was added after the 2003 SARS epidemic.
Safe injection practices: Use a sterile, single-use needle and syringe for each injection. Never recap needles using two hands. Dispose of sharps immediately in a puncture-resistant sharps container. Never use single-dose vials for multiple patients.
Environmental cleaning: High-touch surfaces (bedrails, call lights, IV pumps, doorknobs) require routine cleaning and disinfection between patients and during patient stays. Products must be EPA-registered disinfectants with labeled activity against the target organism.
Sharps safety: Activate safety devices after use. Use needleless IV systems where available. Report all sharps injuries immediately per institutional protocol. Post-exposure prophylaxis (PEP) for HIV must begin within 72 hours of exposure (ideally within 2 hours).
Patient placement: When a patient’s hygiene or behavior increases transmission risk (e.g., uncontained secretions, inability to follow respiratory hygiene), private room placement is preferred even under standard precautions alone.
Transmission-based precautions
Transmission-based precautions are layered on top of standard precautions when a patient is known or suspected to have an infection that requires additional protective measures. The three categories — contact, droplet, and airborne — correspond to the routes by which specific pathogens spread.
Contact precautions
Contact precautions are used when the pathogen spreads through direct contact with the patient or indirect contact with contaminated surfaces and equipment. They are the most commonly used transmission-based precaution in hospital settings.
Indications for contact precautions:
| Pathogen/condition | Clinical notes |
|---|---|
| MRSA (methicillin-resistant Staphylococcus aureus) | Active infection OR colonization; survives on surfaces for months |
| VRE (vancomycin-resistant Enterococcus) | Colonization and infection; highly persistent on environmental surfaces |
| Clostridioides difficile | Spore-forming; requires soap and water hand hygiene (ABHR ineffective against spores) |
| Norovirus | Spore-resistant capsid; ABHR ineffective — soap and water required |
| MDRO organisms (MDR gram-negatives including ESBL, CRE, CRAB) | Drug-resistant pathogens; contact precautions for all confirmed cases |
| Scabies | Mite infestation; spreads via prolonged direct skin contact; treat patient and close contacts |
| Wound infections with uncontained drainage | Major skin, wound, or burn infections not adequately covered by dressing |
| Varicella (chickenpox) — active lesions | Airborne + contact precautions combined (skin lesions are a direct contact risk) |
| Herpes zoster (shingles) — disseminated or immunocompromised host | Airborne + contact precautions; localized zoster in immunocompetent host requires contact only |
PPE required: Gown and gloves on room entry — before touching the patient or any surface in the room. This is non-negotiable under CDC HICPAC guidelines. Gloves are changed after contact with infectious material and before touching clean surfaces within the room.
Room setup: Single-patient room is preferred. When single rooms are unavailable, cohorting (grouping patients with the same organism) is acceptable. Signage must be posted outside the door.
Dedicated equipment: Stethoscope, blood pressure cuff, and thermometer should remain in the room and not be shared between patients. If equipment must be shared, disinfect thoroughly before use on another patient.
Patient transport: Limit transport to medically essential movement. When the patient must leave the room, cover wounds and lesions. Notify the receiving department in advance so they can prepare. The patient should perform hand hygiene before leaving the room.
Discontinuing precautions: Criteria vary by pathogen and institution. For MRSA, three consecutive negative surveillance cultures obtained ≥24 hours apart is a common threshold. For C. diff, most guidelines recommend maintaining contact precautions for the duration of the hospitalization and for at least 48 hours after diarrhea resolves.
Droplet precautions
Droplet precautions apply to pathogens that spread via respiratory droplets larger than 5 microns generated during coughing, sneezing, talking, or procedures such as suctioning. These droplets travel short distances — typically 3–6 feet — and do not remain suspended in the air the way aerosols do.
Indications for droplet precautions:
| Pathogen/condition | Notes |
|---|---|
| Influenza A and B | Droplet + contact for young children and in settings with high aerosol risk |
| Pertussis (Bordetella pertussis) | Highly contagious; droplet until 5 days of effective antibiotic therapy completed |
| Bacterial meningitis (N. meningitidis, H. influenzae) | Droplet until 24 hours of appropriate antibiotic therapy; chemoprophylaxis for close contacts |
| Rubella (German measles) | Droplet until 7 days after rash onset |
| Mumps | Droplet until 5 days after parotid swelling onset |
| Parvovirus B19 | Droplet precautions in immunocompromised and pregnant patients; aplastic crisis is the main risk |
| Adenovirus | Droplet + contact |
| COVID-19 (standard care, non-AGP) | Droplet + contact as minimum; airborne precautions for aerosol-generating procedures |
PPE required: A surgical mask is worn by the healthcare worker when working within 3 feet of the patient (some institutions enforce mask use upon room entry regardless of distance). Eye protection is added when splash or spray is anticipated. A gown is added when direct contact with the patient is expected.
Spatial considerations: The patient should be placed in a single room when available. The door may remain open — negative pressure is not required for droplet precautions. If a single room is not available, maintain a spatial separation of at least 3 feet between the droplet-precaution patient and other patients. A mask should be placed on the patient during transport.
Airborne precautions
Airborne precautions are required when pathogens are transmitted via droplet nuclei — particles of 5 microns or smaller that can remain suspended in the air for extended periods and travel significant distances on air currents. Standard surgical masks are not protective against airborne pathogens.
Indications for airborne precautions:
| Pathogen/condition | Notes |
|---|---|
| Tuberculosis (pulmonary or laryngeal) | Prototype airborne pathogen; negative pressure room required; N95 respirator mandatory for HCW |
| Measles (rubeola) | One of the most contagious pathogens known; only immune personnel should enter the room |
| Varicella (chickenpox) — active | Airborne + contact; susceptible HCWs should not enter the room |
| Herpes zoster — disseminated or immunocompromised | Airborne + contact; localized zoster in immunocompetent host is contact only |
| COVID-19 — aerosol-generating procedures (AGPs) | N95 + gown + gloves + eye protection; AGPs include intubation, bronchoscopy, high-flow O2, nebulizer treatments, BiPAP/CPAP |
| Monkeypox (mpox) — disseminated | Airborne + contact + standard precautions during respiratory procedures |
Room requirements: An airborne infection isolation room (AIIR) is mandatory. Key specifications per CDC and the American Institute of Architects guidelines:
- Negative air pressure relative to the corridor (air flows into the room, not out)
- Minimum 6 air changes per hour for existing construction; 12 air changes per hour for new construction
- Dedicated exhaust to the outdoors or HEPA filtration of recirculated air
- Door must remain closed at all times
- The number of AIIRs an institution maintains is regulated and tracked
PPE required: A fit-tested N95 respirator (or higher — PAPR or elastomeric half-face respirator). Standard surgical masks do not filter particles to the required level. Healthcare workers must be fit-tested for the specific N95 model they use. If a susceptible (non-immune) HCW has no N95 available, they should not enter the room of a patient with measles or varicella.
Patient transport: The patient wears a surgical mask during transport to limit dispersal of droplet nuclei. The destination department must be notified in advance. Procedures on airborne-precaution patients should be performed in the AIIR or, if the patient must leave, in a room with equivalent ventilation.
PPE selection guide
| Condition/pathogen | Gloves | Gown | Mask type | Eye protection | Room type |
|---|---|---|---|---|---|
| Standard precautions (any patient, task-based) | When contact with blood/body fluids expected | When splash/spray to clothing expected | Surgical mask when splash to face expected | When splash/spray to eyes expected | Any |
| MRSA | On room entry | On room entry | Not required (unless splash risk) | Not required (unless splash risk) | Single room preferred |
| C. diff | On room entry | On room entry | Not required (unless splash risk) | Not required (unless splash risk) | Single room preferred; ABHR ineffective — use soap and water |
| VRE | On room entry | On room entry | Not required | Not required | Single room preferred |
| Influenza | Yes | Yes | Surgical mask within 6 feet | If splash risk | Single room; door may remain open |
| Meningococcal meningitis | Yes | Yes | Surgical mask | If splash risk | Single room; door may remain open |
| Tuberculosis | Not required (contact not a risk for TB) | Not required | N95 fit-tested respirator | If splash risk (hemoptysis, bronchoscopy) | AIIR — negative pressure, ≥6 ACH |
| Measles | Not required unless contact risk | Not required unless contact risk | N95 (immune HCWs only in room) | Not required | AIIR — negative pressure |
| Varicella (active) | On room entry | On room entry | N95 (immune HCWs only in room) | Not required unless splash risk | AIIR — negative pressure |
| COVID-19 (non-AGP) | On room entry | On room entry | Surgical mask minimum; N95 preferred | Yes | Single room; AIIR preferred |
| COVID-19 (AGP — intubation, bronchoscopy, high-flow O2) | On room entry | On room entry | N95 minimum | Full face shield or goggles | AIIR required |
Hand hygiene
Hand hygiene is the most evidence-based, highest-impact infection control intervention available to nurses. The WHO “Five Moments of Hand Hygiene” framework, adopted by the CDC and Joint Commission, defines the five critical junctures:
- Before touching a patient
- Before a clean or aseptic procedure (e.g., inserting an IV, drawing blood cultures, accessing a central line)
- After exposure risk — after contact with blood, body fluids, mucous membranes, or non-intact skin
- After touching a patient
- After touching patient surroundings — even if you did not touch the patient directly
Alcohol-based hand rub vs. soap and water
Alcohol-based hand rub (ABHR) — ethanol or isopropanol-based gel or foam — is the preferred hand hygiene method in most clinical situations. It is faster than soap and water, causes less skin irritation with repeated use, and achieves greater log reduction against most healthcare pathogens within 15–30 seconds of correct technique.
However, ABHR does NOT kill spores. This is the most clinically important exception in infection control:
- C. difficile: Produces heat- and alcohol-resistant endospores. ABHR does not eliminate C. diff spores. Soap and water is required — the mechanical friction of lathering and rinsing physically removes spores from the hands.
- Norovirus: Has an alcohol-resistant non-enveloped capsid. ABHR is significantly less effective; soap and water is preferred, especially after direct patient contact or contact with contaminated surfaces.
When soap and water is required (not just preferred):
- After caring for a patient on C. diff contact precautions
- After caring for a patient with known or suspected norovirus
- When hands are visibly soiled or contaminated with blood or body fluids
- Before eating, after using the restroom
Correct ABHR technique: apply enough product to cover all surfaces of both hands, rub together for 20–30 seconds until hands are dry. Do not wipe off — allow to air dry completely.
Correct soap and water technique: wet hands, apply soap, lather and scrub for at least 20 seconds covering all surfaces including fingertips and between fingers, rinse thoroughly, dry with a single-use towel, use the towel to turn off the faucet.
NCLEX tips and common confusions
Infection control consistently appears on NCLEX-RN and NCLEX-PN. The following areas produce the most wrong answers.
The TB vs. droplet confusion
Tuberculosis requires airborne precautions — not droplet. This is the most common wrong answer on NCLEX isolation questions. TB (Mycobacterium tuberculosis) is transmitted via droplet nuclei that are small enough to remain suspended in air and travel beyond 6 feet. A surgical mask does not provide protection. An N95 fit-tested respirator is required. The patient requires an AIIR with negative pressure.
Meningitis caused by Neisseria meningitidis requires droplet precautions (surgical mask), not airborne. Students frequently confuse these two because both are serious infections — but the transmission routes are completely different.
The C. diff ABHR exception
NCLEX frequently tests this: alcohol-based hand rub does not kill C. diff spores. When the question stem describes a patient with C. diff or contact precautions for C. diff, the correct hand hygiene answer is soap and water. The same applies to norovirus, though C. diff appears more frequently.
Standard precautions are always active
Standard precautions apply to all patients, including those with no known infection. NCLEX questions sometimes ask about a patient with no listed diagnosis — the correct answer still includes standard precautions. Transmission-based precautions are added on top, not instead.
Varicella requires two precaution types
Active varicella (chickenpox) and disseminated herpes zoster require both airborne AND contact precautions. Students often select only airborne (because the virus is airborne-transmitted) and miss the contact component for skin lesions. Both types must be in place simultaneously.
PPE donning and doffing order
NCLEX tests the correct sequence. Donning order: gown first, then mask/respirator, then eye protection, then gloves. Doffing order (most contaminated items removed first): gloves first, then eye protection, then gown, then mask/respirator. Hand hygiene is performed after removing gloves and again after all PPE is removed.
When to discontinue airborne precautions for TB
A patient with suspected pulmonary TB may be removed from airborne precautions when:
- Three consecutive sputum AFB smears collected on separate days are negative, AND
- A clinician determines an alternative diagnosis is likely OR the patient is responding to appropriate TB therapy
Negative smears alone are not automatically sufficient — clinical judgment is required. A single negative smear is not enough to discontinue precautions.
Related references
For disease-specific infection control detail, see the dedicated reference pages on this site:
- MRSA nursing reference — contact precaution management, vancomycin monitoring, decolonization
- C. diff nursing reference — severity classification, IDSA treatment guidelines, the soap-and-water rule
- Tuberculosis nursing reference — RIPE regimen, DOT, AFB smear interpretation, airborne isolation management
- COVID-19 nursing reference — PPE guidance, aerosol-generating procedure definitions, current precaution tiers
- Influenza nursing reference — droplet precaution timing, antiviral therapy, chemoprophylaxis
- Sepsis nursing reference — HAI as a leading cause of sepsis, source control, 1-hour bundle
- Wound assessment guide — systematic assessment of wounds requiring contact precautions
- Vital signs by age — fever thresholds that trigger infection workup across age groups