Legionella Pneumophila Airway Colonisation in Patients Admitted to Hospital

Nosocomial infections are often caused by the opportunistic pathogen Legionella pneumophila which may cause a life-threatening disease in immuno-compromised individuals. Infection may occur either by inspiration of contaminated aerosol, or by aspiration of contaminated water. A large number of nosocomial infections, community infections, or travel-related infections have been reported. For nosocomial infections the most frequent route of transmission is aspiration, often from water taps and showerheads, while travel-related infection is more often aerosolborne. Person-to-person transmission has not been demonstrated. Diagnosis of Legionella can be confirmed in the laboratory by a variety of techniques including evidence of urinary antigen, direct immunofluorescence, PCR, evidence of an elevated specific antibody titre or best of all culture. Transplant patients are at particular risk during an outbreak and if infected may not survive. An outbreak at the Institute for Clinical and Experimental Medicine lead to remedial action to remove the organism from the hot water supply system and now superheating and disinfection is regularly carried out together with monitoring for Legionella. To examine a possible role for oropharyngeal colonisation in disease transmission to patients undergoing immunosuppressive therapy aspirates from the upper airways of patients have been examined. A number of patients monitored before surgery for kidney, liver, and pancreas transplantation have shown a Legionella DFA positive reaction. Over the study period 24/324 kidney, 16/95 liver and 6/36 pancreas transplant candidates have been tested positive.