Clusters of infectious diseases in German nursing homes – observations from a prospective infection surveillance study, October 2008 to August 2009

A prospective infection surveillance study was carried out among residents of seven nursing homes in and around Berlin, Germany, from October 2008 to August 2009. A considerable number of infections were found to occur in clusters. Active surveillance was carried out using pre-established case definitions of infections in nursing homes (McGeer criteria). Case finding was based on routine nursing files. Infection rates were calculated per 1,000 resident days. Clusters were identified using a pre-established definition. In total 511 residents were observed during 74,626 resident days (rd), and 393 infections occurred in 243 participants, giving an overall incidence of infection of 5.3 per 1,000 rd. The most common infections were gastrointestinal infections (n=122; 1.6/1,000 rd), acute respiratory disease (n=86; 1.2/1,000 rd) and urinary tract infections (n=71; 1.0/1,000 rd). Seven clusters involving 74 infections in 57 residents were observed: three of acute respiratory disease, three of acute gastrointestinal disease and one of conjunctivitis. Attack rates varied between 11% and 61%. Clusters occurred frequently in the observed nursing homes and could be detected by infection surveillance based on routine documentation.