Investigating the Incidence of Multi-drug Resistant Bacteria in a Freshwater Stream in Hong Kong

Abstract:

Goal

Following the discovery of multi-drug resistant strains of Enterobacteriaceae in a local stream, which included some with extended-spectrum beta-lactamases (ESBLs), this project aims to survey the surrounding area and waterways to discover hotspots and possible sources.

Background

Multidrug-resistant strains of bacteria (“superbugs”) represent an increasing risk to human and animal health because they make infections harder to treat. Although genes giving resistance occur naturally, widespread and indiscriminate use of antimicrobial agents since the mid-20th century has created strong selection pressure that has encouraged their proliferation.

In an earlier sampling, a freshwater stream in Hong Kong, next to a school campus and flowing past a nearby hospital and medical school, yielded strains of Serratia marcescens and an Enterobacter sp. not only resistant to penicillins, cephalosporins and Augmentin, but also to vancomycin. Genome sequencing subsequently revealed an ampC-type beta-lactamase with an extended spectrum of activity – an ESBL (Wilson and Török, 2018). In addition, these microbes carried IncFIB and IncFII plasmids, previously linked to virulence and antimicrobial resistance (Rozwandowicz et al., 2018).

Since hospital drains and sinks are known sources of multi-drug resistant microbes, these resistant strains may also have an identifiable local origin.

Method

Extracts of samples collected from several locations near the stream where the Enterobacteriaceae were found will be cultured on agar containing Augmentin. As well as recording the number of resistant colonies associated with each location, PCR will be used to estimate the proportion carrying ESBL genes. Genomic sequencing and phylogenetic analysis will be used to look for evolutionary relationships between selected isolates.

References

Rozwandowicz, M., Brouwer, M. S. M., Fischer, J., Wagenaar, J. A., Gonzalez-Zorn, B., Guerra, B., Mevius, D.J., Hordijk, J. (2018) Plasmids carrying antimicrobial resistance genes in Enterobacteriaceae. Journal of Antimicrobial Chemotherapy, 73(5), 1121–1137. doi: 10.1093/jac/dkx488

Wilson, H. , Török, M.E. (2018) Extended-spectrum β-lactamase-producing and carbapenemase-producing Enterobacteriaceae, Microbial Genomics, 4(7): e000197. doi: 10.1099/mgen.0.000197