Abstract
Background: Legionnaires' disease (LD) is a potentially fatal pneumonia predominantly caused by infection due to Legionella pneumophila although more than 50 other Legionella species are described. Water systems contaminated with Legionella spp. are the implicated sources of Legionnaires' disease. In this study, we aimed to assess Legionella contamination in the water sources of a tertiary care hospital and to determine the virulence properties and molecular characteristics of L. pneumophila environmental isolates.Methods: During May 2015 through August 2018, a total of 201 hospital water samples were tested for L. pneumophila by standardized culture procedures; environmental isolates were examined for the presence of two virulence genes: Legionella vir homolog (lvh) and repeats in structural toxin (rtxA) by PCR. The genotyping of isolates was performed by sequence-based typing (SBT) according to the protocol of the European Study Group for Legionella Infections (ESGLI).Results: L. pneumophila was isolated from 38/201 (18.9%) water samples; among the 46 isolates, the lvh locus was present in 45 (97.8%), the rtxA locus was found in 45 (97.8%), and both loci were found in 44 (95.7%) isolates. A total of 23 sequence types (STs) were identified among the 44 isolates (index of discrimination [IOD] of 0.929), and 11/23 (47.8%) STs were new to the ESGLI database.Conclusions: The study results showed genetic diversity in L. pneumophila isolates from the hospital environment along with a high percentage of pathogenicity loci. Besides, certain STs may have an increased ability to cause legionellosis, thus requires specific infection control and prevention strategies whenever identified.
Highlights
Legionella pneumophila, the etiological agent of atypical pneumonia known as Legionnaires’ disease (LD), is the inhabitants of both natural and human-made aquatic environments [1]
Among the 201 water samples collected during the study period, 38 (18.9%; 19 potable and 19 non-potable) were positive for L. pneumophila by culture
Regarding the 38 samples tested positive for L. pneumophila, the presence of Lp1 was detected in 25 (65.8%) samples, which included 11 potable and 14 non-potable water samples
Summary
Legionella pneumophila, the etiological agent of atypical pneumonia known as Legionnaires’ disease (LD), is the inhabitants of both natural and human-made aquatic environments [1]. The genus Legionella includes more than 70 distinct serogroups from >60 known species, and of these, at least 30 species have been associated with opportunistic infections in humans. The periodic monitoring of Legionella in the hospital water systems allows for risk prediction and the elimination of this pathogen from possible infection sources [7]. Water systems contaminated with Legionella spp. are the implicated sources of Legionnaires’ disease. We aimed to assess Legionella contamination in the water sources of a tertiary care hospital and to determine the virulence properties and molecular characteristics of L. pneumophila environmental isolates
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