Antibiotic resistance in a predominantly occurring Gram-negative bacterial community from treated sewage to assess the need for going beyond coliform standards

Niha Mohan Kulshreshtha,Sudipti Arora,Sandeep Singh Shekhawat,Vivekanand Vivekanand,Akhilendra Bhushan Gupta,Rinki Mishra

doi:10.2166/wqrj.2021.001

Abstract

Abstract Antibiotic resistance surveillance is an objective of global action plan on antimicrobial resistance endorsed by the World Health Organization. The current study reports the identification of frequently occurring Gram-negative bacterial community (GNBC) previously isolated from municipal treated wastewater and their antibiotic resistance profiles. Further, the genes responsible for extended-spectrum beta lactamases (ESBL) activity were identified in ESBL-positive organisms. The isolates were characterized using biochemical assays and identification was confirmed by VITEK®2 automated system. Antibiotic susceptibility testing against seven different classes of antibiotics was also performed on the same system using AST-N280 cards. The most dominant isolates identified were Acinetobacter baumannii, Morganella morganii, Kluyvera intermedia, Stenotrophomonas maltophilia, Escherichia coli, Aeromonas hydrophila/caviae, Klebsiella pneumoniae, Enterobacter cloacae and Citrobacter freundii. The isolates were observed to be significantly resistant against the antibiotics amoxicillin-clavulanic acid, cefuroxime, cefuroxime axetil and colistin. Two of the isolates, E. cloacae sp. dissolvens and S. maltophilia, were found to be positive for ESBL activity encoded by blaCTX-M gene. The possible intrusion of hospital wastewater in domestic sewage is also discussed. This study may help assess the risk of wastewater reuse by detecting dominant bacteria as a step towards the development of new microbiological standards.

Highlights

Over the last few years, the emergence and dissemination of antibiotic resistance among bacteria has become a serious public health concern throughout the world (Rabbani et al 2017)
It has been estimated that almost 99% of total bacterial community in treated wastewater could have the potential of any type of antibiotic resistance acquisition (Rizzo et al 2013)
On the basis of results of VITEK®2, the isolates were identified as Acinetobacter baumannii (JPJC-S1), Enterobacter cloacae ssp. dissolvens (JPJC-S2), Citrobacter freundii (JPJC-S3), Kluyvera intermedia (JPJC-S4), Figure 2 | Phenotypic confirmatory disc diffusion test showing an increase in zone size of .5 mm for cefotaxime/clavulanic acid

Summary

Introduction

Over the last few years, the emergence and dissemination of antibiotic resistance among bacteria has become a serious public health concern throughout the world (Rabbani et al 2017). The emergence of antibiotic resistance has been perceived as a clinical problem, but currently, non-clinical environments have revealed important factors in the spread of antibiotic resistance genes (ARGs) (Berglund 2015). Sewage treatment plants (STPs) have emerged as a major source of antibiotic release into the environment. They serve as a potential hotspot for horizontal gene transfer and selection of antibiotic-resistant bacteria (ARB). It has been estimated that almost 99% of total bacterial community in treated wastewater could have the potential of any type of antibiotic resistance acquisition (Rizzo et al 2013)

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Results

Conclusion