AUTHOR=Nordhoff Katja , Scharlach Martina , Effelsberg Natalie , Knorr Carolin , Rocker Dagmar , Claussen Katja , Egelkamp Richard , Mellmann Alexander C. , Moss Andreas , Müller Ilona , Roth Sarah Andrea , Werckenthin Christiane , Wöhlke Anne , Ehlers Joachim , Köck Robin 

TITLE=Epidemiology and zoonotic transmission of mcr-positive and carbapenemase-producing Enterobacterales on German turkey farms

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1183984

DOI=10.3389/fmicb.2023.1183984

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>The emergence of carbapenem-resistant bacteria causing serious infections may lead to more frequent use of previously abandoned antibiotics like colistin. However, mobile colistin resistance genes (<italic>mcr</italic>) can jeopardise its effectiveness in both human and veterinary medicine. In Germany, turkeys have been identified as the food-producing animal most likely to harbour <italic>mcr</italic>-positive colistin-resistant Enterobacterales (<italic>mcr</italic>-Col-E). Therefore, the aim of the present study was to assess the prevalence of both <italic>mcr</italic>-Col-E and carbapenemase-producing Enterobacterales (CPE) in German turkey herds and humans in contact with these herds.</p></sec><sec><title>Methods</title><p>In 2018 and 2019, 175 environmental (boot swabs of turkey faeces) and 46 human stool samples were analysed using a combination of enrichment-based culture, PCR, core genome multilocus sequence typing (cgMLST) and plasmid typing.</p></sec><sec><title>Results</title><p><italic>mcr</italic>-Col-E were detected in 123 of the 175 turkey farms in this study (70.3%). <italic>mcr</italic>-Col-E isolates were <italic>Escherichia coli</italic> (98.4%) and <italic>Klebsiella</italic> spp. (1.6%). Herds that had been treated with colistin were more likely to harbour <italic>mcr</italic>-Col-E, with 82.2% compared to 66.2% in untreated herds (<italic>p</italic> = 0.0298). Prevalence also depended on husbandry, with 7.1% <italic>mcr</italic>-Col-E in organic farms compared to 74.5% in conventional ones (<italic>p</italic> &lt; 0.001). In addition, four of the 46 (8.7%) human participants were colonised with <italic>mcr</italic>-Col-E. <italic>mcr</italic>-Col-E isolates from stables had minimum inhibitory concentrations (MICs) from 4 to ≥ 32 mg/l, human isolates ranged from 4 to 8 mg/l. cgMLST showed no clonal transmission of isolates. For one farm, plasmid typing revealed great similarities between plasmids from an environmental and a human sample. No CPE were found in turkey herds or humans.</p></sec><sec><title>Discussion</title><p>These findings confirm that <italic>mcr</italic>-Col-E-prevalence is high in turkey farms, but no evidence of direct zoonotic transmission of clonal <italic>mcr</italic>-Col-E strains was found. However, the results indicate that plasmids may be transmitted between <italic>E. coli</italic> isolates from animals and humans.</p></sec>