Contamination of the cold water distribution system of health care facilities by Legionella pneumophila: Do we know the true dimension?

M Arvand,K Jungkind,A Hack

doi:10.2807/ese.16.16.19844-en

Abstract

German water guidelines do not recommend routine assessment of cold water for Legionella in healthcare facilities, except if the water temperature at distal sites exceeds 25°C. This study evaluates Legionella contamination in cold and warm water supplies of healthcare facilities in Hesse, Germany, and analyses the relationship between cold water temperature and Legionella contamination. Samples were collected from four facilities, with cases of healthcare-associated Legionnaires' disease or notable contamination of their water supply. Fifty-nine samples were from central lines and 625 from distal sites, comprising 316 cold and 309 warm water samples. Legionella was isolated from central lines in two facilities and from distal sites in four facilities. 17% of all central and 32% of all distal samples were contaminated. At distal sites, cold water samples were more frequently contaminated with Legionella (40% vs 23%, p <0.001) and with higher concentrations of Legionella (≥1,000 colony-forming unit/100 ml) (16% vs 6%, p<0.001) than warm water samples. There was no clear correlation between the cold water temperature at sampling time and the contamination rate. 35% of cold water samples under 20 °C at collection were contaminated. Our data highlight the importance of assessing the cold water supply of healthcare facilities for Legionella in the context of an intensified analysis.

Highlights

Legionnairesdisease (LD) is an important cause of hospital-acquired pneumonia [1]
The investigation was initiated because cases of healthcare-associated LD (hca-LD) were diagnosed in one facility (Facility C) or because periodical analysis had suggested a severe contamination of the water distribution system (WDS) with Legionella
We found higher contamination rates and higher Legionella concentrations in cold water samples than in warm water samples collected from distal sites in three facilities (Figure 1, Table 2)

Summary

Introduction

Legionnairesdisease (LD) is an important cause of hospital-acquired pneumonia [1]. Potable water was recognised as the major environmental source of healthcare-associated LD (hca-LD) in the early 1980s [1]. After this discovery, almost all cases of hca-LD have been linked to potable water [2,3,4,5]. In the United Kingdom, 19 of 20 hospital LD outbreaks from 1980 to 1992 could be attributed to the water distribution system (WDS) [6]. Microaspiration is the major mode of transmission of hca-LD [7]. Because the clinical manifestations are non-specific, and specialised laboratory testing is required, LD is underdiagnosed [1,8]

Methods

Results

Conclusion