RESUMO
We used gene sequencing to determine whether clinical (sporadic, epidemic, and endemic) and environmental isolates of Legionella pneumophila serogroup (sg) 1 belong to specific lineages. A total of 178 clinical and environmental L. pneumophila sg 1 isolates, defined by pulsed-field gel electrophoresis and epidemiological data as sporadic, epidemic, or endemic, were analyzed for polymorphisms in five gene fragments. The fragments belonged to three housekeeping genes (coding for aconitase [acn], aspartate-beta-semialdehyde dehydrogenase [asd], and RNA polymerase beta subunit [rpoB]) and two surface protein genes (coding for the macrophage infectivity potentiator [mip] and the major outer membrane protein [mompS]). The phylogenetic tree inferred from sequence polymorphisms of the five genes identified two large clusters, one consisting of 133 poorly differentiated strains and containing two smaller clusters (10 and 2 strains) unrelated to each other and the other consisting of 42 strains. Clinical and environmental isolates could not be distinguished on this basis, and no link between genetic background and epidemiological type was found, suggesting that other factors are responsible for differences in pathogenicity.
Assuntos
Proteínas de Bactérias/genética , Legionella pneumophila/classificação , Doença dos Legionários/microbiologia , Análise de Sequência de DNA , Microbiologia da Água , Proteínas de Bactérias/química , Técnicas de Tipagem Bacteriana , Sequência de Bases , Hospitais , Humanos , Legionella pneumophila/genética , Legionella pneumophila/isolamento & purificação , Dados de Sequência Molecular , Filogenia , Abastecimento de ÁguaRESUMO
A new method for the rapid and sensitive detection of Legionella pneumophila in hot water systems has been developed. The method is based on an IF assay combined with detection by solid-phase cytometry. This method allowed the enumeration of L. pneumophila serogroup 1 and L. pneumophila serogroups 2 to 6, 8 to 10, and 12 to 15 in tap water samples within 3 to 4 h. The sensitivity of the method was between 10 and 100 bacteria per liter and was principally limited by the filtration capacity of membranes. The specificity of the antibody was evaluated against 15 non-Legionella strains, and no cross-reactivity was observed. When the method was applied to natural waters, direct counts of L. pneumophila were compared with the number of CFU obtained by the standard culture method. Direct counts were always higher than culturable counts, and the ratio between the two methods ranged from 1.4 to 325. Solid-phase cytometry offers a fast and sensitive alternative to the culture method for L. pneumophila screening in hot water systems.
Assuntos
Contagem de Colônia Microbiana/métodos , Legionella pneumophila/isolamento & purificação , Microbiologia da Água , Contagem de Colônia Microbiana/estatística & dados numéricos , Imunofluorescência , Temperatura Alta , Legionella pneumophila/imunologia , Sensibilidade e Especificidade , Especificidade da Espécie , Coloração e Rotulagem/métodosRESUMO
In France, the clinical distribution of Legionella species and serogroups does not correspond to their environmental distribution. Legionella pneumophila serogroup 1 is more prevalent among clinical isolates (95.4%) than in the environment (28.2%), whereas L. anisa is more frequent in the environment (13.8%) than in the clinical setting (0.8%).
Assuntos
Legionella/isolamento & purificação , França , Humanos , Legionella/classificação , Sorotipagem , Microbiologia da ÁguaRESUMO
An analysis of 691 French clinical Legionella isolates showed that the endemic L. pneumophila serogroup 1 strain Paris was responsible for 12.2% of all cases of legionellosis and had a specific pulsed-field gel electrophoresis pattern. We also demonstrated the presence of this endemic clone throughout Europe.
