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

Abstract

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). Of the 12 hospital-associated Legionella non-sg 1 patient isolates, 4 were serogrouped as sg 4, 7 as sg 10, and one as sg 6. Using AFLP fingerprinting all serogroup (sg) 4 and 10 isolates were genetically related except for minor variations. Furthermore, sg 4 isolates were identical in AFLP to sg 10 isolates. Patient isolates were also identical to isolates found in the water system of several hospital buildings, but quite unrelated to isolates obtained in a subsequent outbreak at the same hospital caused by L. pneumophila sg 1. Serogroup variations in outbreaks may occur despite a common molecular fingerprinting pattern. Evidently, the L. pneumophila sg 4 and 10 strains were closely related genetically, which raises the question whether this variation in phenotype is due to a genetic event or to a variable phenotypic expression. Genetic fingerprinting should be used in conjunction with serogrouping in epidemiological investigations.

Legionella anisa , a Possible Indicator of Water Contamination by Legionella pneumophila

“…Legionella species are ubiquitous in many water systems (6,8,9,17,22,27)-including hospital water systems (30,31,39)-with Legionella pneumophila and Legionella species other than L. pneumophila isolated together (3,11) or alone (19,37). The most frequent species are L. pneumophila and L. anisa (5,12,16,18,36).…”

Hospital-wide Eradication of a NosocomialLegionella pneumophilaSerogroup 1 Outbreak

“…Human infection is by inhalation of aerosol droplets, with infection of pulmonary alveolar macrophages causing Legionnaires' disease [1]. Nosocomial legionellosis is typically caused by L. pneumophila serogroup 1 (LPSG1) infection, although occasional outbreaks due to other L. pneumophila serogroups and nonpneumophila Legionella species [2] have been reported [3,4]. Nosocomial Legionnaires' disease outbreaks can be either intermittent or continue for years [5].…”

Effects of Japan Sea Proper Water on the growth ofLegionella pneumophila, Escherichia coli, andStaphylococcus aureus

“…Legionella usually does not harm healthy people, but can seriously infect immunocompromised patients in hospitals or elderly people. Legionnaires' disease has been recognized in many countries throughout the world (16)(17)(18)(19). In addition, a large outbreak of Legionnaires' disease caused by an inadequate circulating and filtration system for communal bath water has been reported in Japan (20).…”