Salmonella and Antimicrobial Resistance in Wild Rodents-True or False Threat?

Magdalena Skarżyńska,Dariusz Wasyl,Jacek Żmudzki,Artur Jabłoński,Magdalena Zając,Ewelina Kamińska,Arkadiusz Bomba

doi:10.3390/pathogens9090771

Magdalena Skarżyńska, Dariusz Wasyl + Show 5 more

Open Access

https://doi.org/10.3390/pathogens9090771

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Abstract

Transmission of pathogenic and resistant bacteria from wildlife to the bacterial gene pool in nature affects the ecosystem. Hence, we studied intestine content of five wild rodent species: the yellow-necked wood mouse (Apodemus flavicollis, n = 121), striped field mouse (Apodemus agrarius, n = 75), common vole (Microtus arvalis, n = 37), bank vole (Myodes glareolus, n = 3), and house mouse (Mus musculus, n = 1) to assess their potential role as an antimicrobial resistance (AMR) and Salmonella vector. The methods adopted from official AMR monitoring of slaughtered animals were applied and supplemented with colistin resistance screening. Whole-genome sequencing of obtained bacteria elucidated their epidemiological relationships and zoonotic potential. The study revealed no indications of public health relevance of wild rodents from the sampled area in Salmonella spread and their limited role in AMR dissemination. Of 263 recovered E. coli, the vast majority was pan-susceptible, and as few as 5 E. coli showed any resistance. In four colistin-resistant strains neither the known mcr genes nor known mutations in pmr genes were found. One of these strains was tetracycline-resistant due to tet(B). High diversity of virulence factors (n = 43) noted in tested strains including ibeA, cdtB, air, eilA, astA, vat, pic reported in clinically relevant types of enteric E. coli indicate that rodents may be involved in the ecological cycle of these bacteria. Most of the strains represented unique sequence types and ST10805, ST10806, ST10810, ST10824 were revealed for the first time, showing genomic heterogeneity of the strains. The study broadened the knowledge on phylogenetic diversity and structure of the E. coli population in wild rodents.

Highlights

Increasing antimicrobial resistance (AMR) of bacteria is a challenging problem that poses a threat to public health
In E. coli showing colistin, Minimal inhibitory concentration (MIC) > 2 mg/L Whole-genome sequencing (WGS) revealed neither the known plasmid-mediated mcr genes nor known mutations in pmrA and pmrB genes. Those strains exhibited several yet unknown point mutations in pmrA and pmrB but most of them were found in colistin susceptible E. coli (Table S1)
Two colistin-resistant strains possessed single mutations that were not detected in any susceptible ones: pmrB p.L10R resulting in nucleotide change CTG into CGG and out of frame deletion pmrB p.L27_F31delinsL (Figure S4)

Summary

Introduction

Increasing antimicrobial resistance (AMR) of bacteria is a challenging problem that poses a threat to public health. AMR led to 33,000 deaths in the European Union (EU) and the European Economic. Area (EEA) in 2015 only [1]. Reports from the United States (US) indicate that over 2.8 million antimicrobial-resistant infections occur each year, and more than 35,000 of these cases are mortal [2]. A large fraction of life-threatening infections is caused by Enterobacterales. Salmonella constantly remains an important zoonotic hazard noted on a global scale. Salmonellosis was the second most frequently reported zoonosis in humans in the EU/EEA, with 91,857 reported cases in 2018 [3]

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