Regrowth of Legionella pneumophila in a heat-disinfected plumbing system.
We examined the factors involved in the occurrence of Legionellaceae in a hospital water system and the recontamination by Legionella pneumophila after a thermal disinfection procedure was studied.
Three months after the heat treatment (70°C), the regrowth of the two prevalent Legionella strains (L. pneumophila serogroup 1 [Oxford-like] and L. pneumophila serogroup 2) reached the original level of cell numbers.
Genomic analysis (pulsed-field gel electrophoresis) revealed the strains to be survivors of the decontamination.
Temperature tolerance experiments showed that the serogroup 1 strain exhibited a higher tolerance to 60°C than the serogroup 2 strain, which could account for the order of reappearance of the strains after the heat treatment.
Potential host amoebae, including Acanthamoeba spp. and Vahlkampfia spp., which are known to play a critical role in the amplification process of Legionella, were isolated from the plumbing system.
In-vitro studies demonstrated both Legionella strains for a similar rate of multiplication in A. castellanii.
In competitive coinfections, however, the serogroup 1 strain achieved a higher rate of multiplication if compared with the serogroup 2 strain.
Mots-clés Pascal : Legionella pneumophila, Legionellaceae, Bactérie, Milieu hospitalier, Eau potable, Canalisation eau potable, Contamination biologique, Récidive, Traitement eau potable, Traitement thermique, Désinfection, Pollution eau
Mots-clés Pascal anglais : Legionella pneumophila, Legionellaceae, Bacteria, Hospital environment, Drinking water, Drinking water pipe, Biological contamination, Relapse, Drinking water treatment, Heat treatment, Disinfection, Water pollution
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0133221
Code Inist : 002B30A02C. Création : 16/11/1999.