Reducing the aspiration risks of waterborne pathogens

During the past 5-10 years healthcareacquired infections have been the subject of very high levels of public, media, and government attention. Unacceptable levels of sickness and death have become associated with poor hand hygiene and inadequate cleaning. In many countries, initiatives addressing education, cleaning, and audit, together with compulsory reporting of infections, have brought about benefits, leading (in some cases) to the reduction of headline rates of infections, such as methicillinresistant Staphylococcus aureus (MRSA), Clostridium difficile, and Legionnaires’ Disease. It is readily accepted now that a common mode of transmission is contact between the patient, the staff, and the environment. A number of studies have shown that outbreaks can be reduced via improved hand hygiene compliance and better cleaning of the environment. However, transmission of infection via the air has often been less well investigated, sometimes leading to complacency over this mode of transmission.

Airborne transmission

It is clearly understood now that tuberculosis (TB; Mycobacterium tuberculosis) is transmitted through the air, and can be a source of outbreak in hospitals. Healthcare workers infected with TB can spread the infection widely. Similarly, norovirus can be transmitted by aerosol, and is difficult to contain in a hospital ward without sufficient single rooms with en-suite toilets. Historically, natural ventilation was seen to be beneficial in hospital wards, and was part of hospital design. With the advent of sealed, high-rise buildings and forced ventilation, expensive negative pressure rooms have sometimes been introduced to house patients with infections thought likely to be transmitted by aerosol.