A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels.

Eugenia Yakunin,Jacob Moran-Gilad,Lea Valinsky,Eszter Kostyal,Itamar Grotto,Vered Agmon

doi:10.3390/pathogens9060414

Eugenia Yakunin, Jacob Moran-Gilad + Show 4 more

Open Access

https://doi.org/10.3390/pathogens9060414

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Abstract

Exposure to Legionella spp. contaminated aerosols in hotel settings confers risk for travel-associated Legionnaire’s disease (TALD). In this study, we investigated the prevalence of Legionella contamination and its molecular diversity in hotels and resorts across Israel. The study was comprised of a convenience sample of water systems from 168 hotels and resorts countrywide, routinely inspected between March 2015 and February 2017. Isolation and quantitation of Legionella were performed in a water laboratory using the ISO 11731 method. The distribution of Legionella isolates was analyzed according to geography and source. The genetic diversity of a subset of isolates was analyzed by sequence-based typing (SBT) at the National Reference Laboratory for Legionella and compared to the national database. Out of 2830 samples tested, 470 (17%) obtained from 102 different premises (60% of hotels) were positive for Legionella spp. In 230 samples (49% of all positive, 8% of total samples), accounting for 37% of hotels, Legionella spp. counts exceeded the regulatory threshold of 1000 CFU/L. The most frequently contaminated water sources were cooling towers (38%), followed by faucets, hot tubs, water lines, and storage tanks (14–17% each). Furthermore, 32% and 17% of samples obtained from cooling towers and hot tubs, respectively, exceeded the regulatory thresholds. SBT was performed on 78 strains and revealed 27 different sequence types (STs), including two novel STs. The most prevalent STs found were ST1 (26%), ST87 (10%), ST93 (6%), and ST461 and ST1516 (5% each). Several L. pneumophila STs were found to be limited to certain geographical regions. This is the first study to investigate the prevalence and diversity of Legionella in hotels and resorts in Israel during non-outbreak environmental inspections. These findings will inform risk assessment, surveillance, and control measures of TALD.

Highlights

Legionella is a Gram-negative bacterium found ubiquitously in aqueous environments, which can multiply quickly in man-made water systems [1]
We investigated, for the first time, the prevalence and characteristics of environmental Legionella spp. in the Israeli hotel setting as part of routine inspections
The abundance of Legionella pneumophila (Lp) in the tourism sector is a continuous focus of attention in Legionella research, due to its possible implications to public health

Summary

Introduction

Legionella is a Gram-negative bacterium found ubiquitously in aqueous environments, which can multiply quickly in man-made water systems [1]. Legionella spp. are considered potentially pathogenic for humans, Legionella pneumophila (Lp) causes the vast majority of LD cases, and of the 16 known Lp serogroups (sg), sg accounts for over 80% of LD cases [7,8]. Several recent studies have focused on the prevalence and distribution of Legionella in water systems of hotels in non-outbreak situations. These studies revealed variable rates of contamination and species diversity [18,19,20,21], but limited data is published on the molecular diversity of Legionella spp. in hotel settings [22,23,24]. We investigated, for the first time, the prevalence and characteristics of environmental Legionella spp. in the Israeli hotel setting as part of routine inspections

Legionella Contamination Rates

Geographic distribution obtainedfrom fromthe the168

Distribution of Serotypes

Phylogenetic Analysis

Laboratory Methods

Materials and Methods