Response of the Bacterial Community and Antibiotic Resistance in Overnight Stagnant Water from a Municipal Pipeline.

Minglu Zhang,Miao Bai,Kaizong Lin,Shaofeng Xu,He Zhou,Lingyue Zhang,Can Zhang,Mengyao Xu,Lei Zhang

doi:10.3390/ijerph17061995

Abstract

Although drinking water safety has raised considerable concern, to date, the hidden health risks in newly released overnight water from a municipal pipeline have seldom received attention. In this study, bacterial community composition and the response of antibiotic-resistant bacteria (ARB) to ciprofloxacin, azithromycin, tetracycline, penicillin, and cephalosporin in overnight stagnant water were analyzed. With increases in heterotrophic bacteria plate count (HPC) during water stagnation, the numbers of ARB and the ARB/HPC ratios for the five antibiotics in resident water were observed to increase, which illustrated that the prevalence of ARB rose in the pipe network water during stagnation time (ST). Furthermore, during water stagnation for 12 h, an increase in bacteria related to fermentation was also observed. When the ST rose to 48 h, the fermentation bacteria become non-significant, and this was related to the exchange of pipe network water during daytime stagnation within the 48-h period. The antibiotic resistance index (ARI) showed that tetracycline had the highest resistance level in fresh water, and then decreased during water stagnation. When ST increased to 12 h, all ARI values of the five antibiotics were low, which was associated with changes in parameters during water retention and reduced resistance during short-term stagnation. When the ST increased to 24 and 48 h, the resistance to most antibiotics (except for tetracycline) increased, which showed that increasing antibiotic resistance is caused by the formation of biofilms in the pipeline during water stagnation.

Highlights

Drinking water safety problems have a considerable impact on public health
As reported by Karin et al, heterotrophic bacteria plate count (HPC) in tap water sampled from 10 separate households were below the limit of 9.1–9.8 colony-forming units (CFU)/mL, and an obvious increase
These results show that the bacteria in resident water had low resistance to tetracycline during the stagnation time (ST) of 12–48 h

Summary

Introduction

Drinking water safety problems have a considerable impact on public health. the safety of overnight stationary water in municipal pipelines is a relatively neglected issue. The first thing they do after getting up in the morning is to turn on the faucet, wash their face, brush their teeth, boil water and even drink tap water directly. These same procedures are performed when people return to their house or office buildings without considering the safety of tap water which has been in the pipe network for days. Little is known about the hidden health risks of newly released overnight water from municipal pipelines, and the deterioration of resident water quality has been neglected. Heavy metal concentrations in household stationary tap water

Methods

Results

Conclusion