Legionella surveillance in stagnant water systems during COVID-19 lockdown in Istanbul

Abstract

Aim: The aim of this study was to monitor the restricted water systems during the period of COVID-19 lockdown for thewaterborne pathogen Legionella pneumophila. Selected water systems were monitored to evaluate the effect ofstagnation in terms of Legionella colonization.Methodology and results: A total of 160 water samples were taken from buildings which were temporarily shut down orhad restricted usage between April-December 2020. None of the sampling points had Legionella positive history in thelast three years. All water samples were tested using classic microbiological culture as the gold standard and rapidVermicon ScanVIT Legionella test kit combined with epifluorescence microscopy. Sixteen (10%) out of 160 watersamples were recorded as Legionella-positive by both methods, where none of them was positive before the COVID-19lockdown. All positives were tested as L. pneumophila serogroup 1 with latex agglutination kit.Conclusion, significance and impact of study: Colonization of Legionella in stagnant water systems occurs rapidly.Before reopening, routine monitoring in buildings is extremely important especially under restricted use or closure is incase. Flushing, disinfecting and testing are crucial for minimizing the health risks for the public health.