The presence of a specific genotype of Legionella pneumophila serogroup 1 in a hospital and municipal water distribution system over a 12-year period.

The genotypic distribution of Legionella pneumophila serogroup 1 was investigated in the water distribution system of a 450-bed Swedish hospital and the surrounding community. A single genotype identified by amplified fragment length polymorphism (AFLP) analysis, was found in all 34 hospital isolates and in 18 out of 20 community isolates over a 12-y surveillance period. All isolates were either monoclonal antibody subtypes Benidorm or Bellingham.

A hospital-associated outbreak of Legionnaires' disease caused by Legionella pneumophila serogroups 4 and 10 with a common genetic fingerprinting pattern.

An outbreak of eight cases of pneumonia caused by Legionella pneumophila non-serogroup 1 (non-sg 1) occurred at a Swedish university hospital in 1993. Including previous and subsequent sporadic cases, the total number of culture-positive patients was 13. Twelve available non-sg1 isolates from patients were compared to 50 environmental water isolates using a monoclonal antibody test for serogrouping and amplified fragment length polymorphism analysis (AFLP).

A hospital-associated outbreak of Legionnaires' disease caused by Legionella pneumophila serogroup 1 is characterized by stable genetic fingerprinting but variable monoclonal antibody patterns.

An outbreak of 18 pneumonia cases caused by Legionella pneumophila serogroup 1 occurred at a Swedish university hospital 1996 to 1999. Eight clinical isolates obtained by culture from the respiratory tract were compared to 20 environmental isolates from the hospital and to 21 epidemiologically unrelated isolates in Sweden, mostly from patients, by using pulsed-field gel electrophoresis (PFGE), amplified fragment length polymorphism analysis (AFLP), and monoclonal antibody (MAb) typing. All patients and most environmental isolates from the outbreak hospital belonged to the same genotypic cluster in both PFGE and AFLP.