Editing Infection Control and Safety (section)

== Transmission-Based Precautions ==

Transmission-based precautions are used '''in addition to''' standard precautions when the route of transmission is not fully interrupted by standard precautions alone. Begin them empirically on clinical suspicion. Do not wait for culture confirmation.

=== Contact Precautions ===

'''PPE:''' gown and gloves donned before entering the room and removed before exiting. '''Placement:''' single room preferred; cohort patients with the same organism if a single room is unavailable, keeping at least three feet of separation and a privacy curtain. Use dedicated or single-use equipment (stethoscope, blood pressure cuff, thermometer); disinfect any shared equipment before it leaves the room. Limit transport, and cover the infected or colonized area during transport.

'''Common indications:''' multidrug-resistant organisms (MRSA, vancomycin-resistant enterococci, extended-spectrum beta-lactamase producers, carbapenem-resistant Enterobacterales), ''C. difficile'', norovirus and other infectious diarrhea in an incontinent or diapered patient, respiratory syncytial virus, scabies and lice, impetigo, draining wounds or abscesses that cannot be contained by a dressing, herpes simplex in a neonate, and viral conjunctivitis.

'''''C. difficile'' specifics.''' Soap and water for hand hygiene, gown and gloves, private room with dedicated equipment, EPA-registered sporicidal disinfectant for the room, and continuation of precautions for at least 48 hours after diarrhea resolves (many facilities continue until discharge). Do not treat with antimotility agents such as loperamide, which can precipitate toxic megacolon. Antibiotic stewardship is the primary prevention strategy.

=== Droplet Precautions ===

'''PPE:''' surgical mask donned on entry to the room; add eye protection if splash or spray is likely. A respirator is not required. '''Placement:''' single room preferred; if cohorting, keep at least three to six feet between beds with a privacy curtain. The door may remain open. During transport, the '''patient''' wears a surgical mask.

'''Common indications:''' influenza, pertussis (until 5 days of effective therapy), ''Neisseria meningitidis'' meningitis and meningococcemia (until 24 hours of effective therapy), ''Haemophilus influenzae'' type b invasive disease, mumps, rubella, group A streptococcal pharyngitis or pneumonia or scarlet fever (until 24 hours of therapy), diphtheria (pharyngeal), ''Mycoplasma'' pneumonia, and adenovirus and rhinovirus (which are often contact plus droplet).

'''Application note.''' Close contacts of a patient with meningococcal disease, including staff who performed unprotected mouth-to-mouth resuscitation, intubation, or suctioning, require antimicrobial prophylaxis. Simply being in the room with a mask on does not.

=== Airborne Precautions ===

'''PPE:''' a fit-tested N95 filtering facepiece respirator or higher level respiratory protection (powered air-purifying respirator), donned before entering and removed '''after''' leaving the room. Perform a user seal check every time. Fit testing is required before first use and at least annually. '''Placement:''' an airborne infection isolation room (AIIR), meaning a negative-pressure room with at least 6 air changes per hour in existing facilities and at least 12 in new or renovated construction, air exhausted directly outdoors or through a HEPA filter, with the '''door kept closed''' and negative pressure monitored daily when in use. During transport, the '''patient''' wears a surgical mask, not an N95, and skin lesions are covered.

'''Common indications:''' pulmonary or laryngeal tuberculosis, measles (rubeola), varicella (chickenpox) and disseminated herpes zoster (both airborne '''plus''' contact), and smallpox. Localized herpes zoster in an immunocompetent patient requires only standard precautions with the lesions covered.

'''Application note.''' For measles and varicella, only immune staff should enter when possible. After an infectious patient leaves an AIIR, the room must remain vacant long enough for adequate air exchanges, roughly one hour at 6 air changes per hour and about 35 minutes at 12, before an unprotected person enters. Emphasize that the N95 protects the wearer, while the surgical mask on the patient protects everyone else by containing source droplets.

'''Tuberculosis specifics.''' Suspect active pulmonary tuberculosis with cough longer than three weeks, hemoptysis, night sweats, unintentional weight loss, and fever. Place in an AIIR immediately on suspicion, collect three sputum specimens for acid-fast bacilli, and teach adherence to multidrug therapy, since nonadherence drives resistance. A positive tuberculin skin test or interferon-gamma release assay indicates infection, not necessarily active disease; a chest radiograph and sputum are needed to distinguish latent from active disease.

=== Protective Environment ===

A protective environment is used for severely immunocompromised patients, classically allogeneic hematopoietic stem cell transplant recipients. It is '''positive-pressure''' relative to the corridor with HEPA-filtered incoming air, at least 12 air changes per hour, and sealed room construction. Keep the door closed, avoid fresh flowers, potted plants, standing water, and construction dust, and screen visitors for illness. This is not a transmission-based precaution; it protects the patient from the environment rather than protecting others from the patient.

'''Application note.''' A patient who needs both a protective environment and airborne precautions (for example, a transplant patient with varicella) requires an anteroom so the airflow requirements can both be met.

=== Precaution Combinations to Memorize ===

{| class="wikitable"
! Condition !! Precautions
|-
| ''C. difficile'' || Contact plus soap-and-water hand hygiene and sporicidal cleaning
|-
| MRSA, VRE, other MDROs || Contact
|-
| Norovirus, rotavirus || Contact
|-
| Scabies, lice, impetigo || Contact
|-
| Respiratory syncytial virus || Contact (droplet added by many facilities)
|-
| Influenza, pertussis, mumps, rubella || Droplet
|-
| Meningococcal disease || Droplet until 24 hours of effective antibiotics
|-
| Tuberculosis (pulmonary or laryngeal) || Airborne
|-
| Measles || Airborne
|-
| Varicella, disseminated zoster || Airborne plus contact
|-
| Neutropenia or stem cell transplant || Protective environment
|}