The chain of infection

Every precaution breaks a link in the chain.

ChainInfectious agentBacteria, virus, fungusReservoirPeople, surfacesPortal of exitSecretions, bloodMode of transmissionContact, droplet, airPortal of entryMucosa, wounds, linesSusceptible hostOlder, immunocompromised, devices
Chain of infection. Hand hygiene breaks the transmission link and is the single most important prevention measure.

Transmission-based precautions

Add these to standard precautions based on how the organism spreads.

PrecautionExamplesPPE and room
ContactMRSA, VRE, C. difficile, scabies, lice, RSV, draining woundsGown and gloves; private room or cohort; dedicated equipment (stethoscope, BP cuff)
DropletInfluenza, pertussis, N. meningitidis, mumps, rubellaSurgical mask when near the client; private room or spatial separation; client masks for transport
AirborneTuberculosis, measles, varicella, disseminated zosterFit-tested N95 (or higher); negative-pressure airborne infection isolation room; door closed

Varicella and disseminated zoster need airborne and contact precautions together. Follow facility policy for each organism.

Which precaution?ContactMRSA, VRE, C. diffDropletFlu, pertussis,meningococcusAirborneTB, measles, varicella
Precaution categories. When unsure, the more protective precaution is the safer answer until the diagnosis is known.

Personal protective equipment

The sequence prevents contaminating yourself when removing PPE.

Putting on (donning)1. Hand hygiene2. Gown3. Mask or N954. Goggles or face shield5. Gloves (over gown cuffs)Taking off (doffing)1. Gloves (most contaminated)2. Goggles or face shield3. Gown4. Mask or N95 (outside the room forairborne)5. Hand hygienevs
PPE sequence. Some protocols remove gown and gloves together. Perform hand hygiene whenever hands become contaminated during removal.
  • Use soap and water for C. difficile and norovirus: alcohol does not reliably inactivate C. difficile spores; clean surfaces with a sporicidal agent.
  • Never recap used needles; dispose of sharps immediately in a puncture-resistant container.
  • After a needlestick, wash the area with soap and water, report immediately, and follow the post-exposure protocol.

Room assignment and protective precautions

Room and assignment decisions protect both infected and vulnerable clients.

SituationBest choice
Two clients with the same organism (e.g., both MRSA)May share a room (cohorting) per policy
Client with neutropeniaPrivate room; avoid ill visitors and staff; strict hand hygiene; report fever immediately
Pregnant staff memberAvoid assignment to clients with infections risky in pregnancy (for example, rubella, CMV), per policy
Client with suspected TB awaiting resultsAirborne precautions now, before confirmation

Do not place an immunocompromised client in a room with a client who has an infection.

NGN-style case

Precaution selection and soap-and-water rules appear together.

functions Clinical judgment case — new diarrhea

A client receiving clindamycin develops frequent watery diarrhea and a fever. Stool testing is pending. Which actions are appropriate? (1) Contact precautions; (2) clean hands with soap and water after care; (3) use alcohol rub only; (4) dedicated stethoscope; (5) notify the provider.

  1. Recognize cues: antibiotic exposure, watery diarrhea, fever.
  2. Analyze: suspected C. difficile infection.
  3. Start contact precautions now, before results.
  4. Alcohol rub does not reliably remove spores; use soap and water.

Answer. Appropriate: 1, 2, 4, and 5. Not appropriate: 3.