This patient comes from a country with a high prevalence of tuberculosis and is at increased risk for infection with Mycobacterium tuberculosis. Her symptoms of fever, cough, decreased appetite, night sweats, and weight loss, as well as the location of chest infiltrates in the apical area of the upper lobes, are characteristic of pulmonary tuberculosis. M. tuberculosis spreads by airborne particles known as droplet nuclei, which are 5 µm or smaller in size. These airborne particles are expelled when an infected patient sneezes or coughs. Transmission of infection can occur when these airborne particles are inhaled into the lung alveoli. Consequently, this patient should be placed in empiric negative-pressure airborne isolation while further evaluation is pursued. Negative-pressure isolation prevents airborne droplets from escaping the room, and at least 6 to 12 air changes of the room air are provided per hour. Doors to isolation rooms must remain closed, and all persons entering must wear a respirator that has a filtering capacity of 95% and a tight seal over the nose and mouth. Patients in airborne isolation who require transport outside of their isolation room for medical procedures should wear surgical masks that cover their nose and mouth during transport.
Contact isolation is instituted for patients who have a suspected or known illness transmitted by direct contact (such as Clostridium difficile, vancomycin-resistant enterococci, Shigella species, hepatitis A virus).
Droplet isolation is instituted for patients who have a suspected or known illness transmitted by large-particle droplets (>5 µm in size) (for example, Neisseria meningitidis, influenza virus, adenovirus, Bordetella pertussis, Mycoplasma pneumoniae). Droplet precautions involve a face mask without high-level respirator masks or special air handling.
Standard precautions, which include hand hygiene, respiratory hygiene, injection safety measures, use of personal protective equipment (gloves, gowns, face masks/shields, respirators), and appropriate environmental and disinfection measures, are instituted for all patients in a health care setting regardless of illness.