Airborne infections in health care facilities were discussed. Historical beliefs about the transmission of nosocomial infections were summarized. Within hospitals, infective dusts and aerosols, infected or colonized patients, staff, or visitors, and ventilation or air conditioning are major sources of airborne nosocomial infections (ANI). Outside the hospital, soil, dusts from construction and renovation projects, decaying organic materials, and water from cooling towers are important sources of ANI. Airborne nosocomial pathogens derived from inanimate environments generally have been less virulent than those derived from animate sources. A significant number of viruses, bacteria, and fungi can spread by way of airborne mechanisms in hospitals. Viruses that can be spread through the air include rhinoviruses, influenza and parainfluenza viruses, respiratory syncytial virus, and adenoviruses. Bacterial pathogens that can cause ANI originating from humans include the group-A streptococci, Staphylococcus-aureus, and Mycobacterium- tuberculosis. Bacteria that can be spread in infective aerosols in ventilation and air conditioning systems include Pseudomonads, Acinetobacter, Clostridia, and Legionellae. Fungal pathogens that can cause ANI include Aspergillus and Zygomyces species. The relative importance of airborne transmission of infection in the overall problem of nosocomial infection was discussed. Studies of nonepidemic nosocomial infection in hospitals have indicated that 10 to 24% of the infections were spread through the air. Epidemic outbreaks appear to account for 2 to 3.7% of all ANI.
Proceedings of the Workshop on Engineering Controls for Preventing Airborne Infections in Workers in Health Care and Related Facilities, July 14-16, 1993, Cincinnati, Ohio