Antibiotic Resistance among Escherichia coli Isolates from Hospital Wastewater Compared to Community Wastewater

Cristina-Mirabela Gaşpar,Ludovic Toma Cziszter,Ioan Ţibru,Marius Pentea,Monica Butnariu,Cristian Florin Lăzărescu

doi:10.3390/w13233449

Cristina-Mirabela Gaşpar, Ludovic Toma Cziszter + Show 4 more

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https://doi.org/10.3390/w13233449

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Abstract

This study aimed to compare the antibiotic resistance levels of the indicator bacteria Escherichia coli in wastewater samples collected from two hospitals and two urban communities. Antimicrobial susceptibility testing was performed on 81 E. coli isolates (47 from hospitals and 34 from communities) using the disc diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology. Ten antibiotics from nine different classes were chosen. The strains isolated from the community wastewater, compared to those from the hospital wastewater, were not resistant to gentamicin (p = 0.03), but they showed a significantly higher susceptibility—increased exposure to ceftazidime (p = 0.001). Multidrug resistance was observed in 85.11% of the hospital wastewater isolates and 73.53% of the community isolates (p > 0.05). The frequency of the presumed carbapenemase-producing E. coli was higher among the community isolates (76.47% compared to 68.09%) (p > 0.05), whereas the frequency of the presumed extended-spectrum beta-lactamase (ESBL)-producing E. coli was higher among the hospital isolates (21.28% compared to 5.88%) (p > 0.05). The antibiotic resistance rates were high in both the hospital and community wastewaters, with very few significant differences between them, so the community outlet might be a source of resistant bacteria that is at least as important as the well-recognised hospitals.

Highlights

As a result of many years of antibiotic use and abuse, the parent compounds and their functional metabolites, antimicrobial-resistant bacteria (ARB) as well as their resistance genes (ARG) are common and widespread contaminants in many environments [1,2,3,4]
The antibiotic resistance rates were high in both the hospital and community wastewaters, with very few significant differences between them, so the community outlet might be a source of resistant bacteria that is at least as important as the well-recognised hospitals
Treatment processes can reduce the concentrations of pathogens in wastewater, wastewater treatment plant effluents do not show appreciable removal of ARB and ARG in general [5,6], and large amounts of resistant bacteria, possibly of hospital origin, are released into the recipient waters [7]

Summary

Introduction

As a result of many years of antibiotic use and abuse, the parent compounds and their functional metabolites, antimicrobial-resistant bacteria (ARB) as well as their resistance genes (ARG) are common and widespread contaminants in many environments [1,2,3,4]. Facilities to treat municipal wastewater that may harbour large pathogens as Giardia duodenalis and Cryptosporidium spp. are absent or inadequate [9], so retaining or neutralising smaller molecules such as antibiotics, antibiotic-resistant bacteria and their resistance genes becomes even more difficult to achieve through the currently available treatments [1]. Another common problem for many countries, including Romania, which may lead to population exposure to resistant bacteria is aged infrastructure and the fact that leaking sewers are often co-located with municipal drinking water distribution pipes [1]. Other authors claim that there is no evidence for selection for antibiotic resistance in wastewater treatment plants [10]

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