Phenotypic and Genotypic Properties of Fluoroquinolone-Resistant, <i>qnr</i>-Carrying <i>Escherichia coli</i> Isolated from the German Food Chain in 2017
2021
Katharina Juraschek | Carlus Deneke | Silvia Schmoger | Mirjam Grobbel | Burkhard Malorny | Annemarie Käsbohrer | Stefan Schwarz | Diana Meemken | Jens Andre Hammerl
Fluoroquinolones are the highest priority, critically important antimicrobial agents. Resistance development can occur via different mechanisms, with plasmid-mediated quinolone resistance (PMQR) being prevalent in the livestock and food area. Especially, <i>qnr</i> genes, commonly located on mobile genetic elements, are major drivers for the spread of resistance determinants against fluoroquinolones. We investigated the prevalence and characteristics of <i>qnr</i>-positive <i>Escherichia (E.) coli</i> obtained from different monitoring programs in Germany in 2017. Furthermore, we aimed to evaluate commonalities of <i>qnr</i>-carrying plasmids in <i>E. coli</i>. We found <i>qnr</i> to be broadly spread over different livestock and food matrices, and to be present in various sequence types. The <i>qnr</i>-positive isolates were predominantly detected within selectively isolated ESBL (extended spectrum beta-lactamase)-producing <i>E. coli</i>, leading to a frequent association with other resistance genes, especially cephalosporin determinants. Furthermore, we found that <i>qnr</i> correlates with the presence of genes involved in resistance development against quaternary ammonium compounds (<i>qac</i>). The detection of additional point mutations in many isolates within the chromosomal QRDR region led to even higher MIC values against fluoroquinolones for the investigated <i>E. coli</i>. All of these attributes should be carefully taken into account in the risk assessment of <i>qnr</i>-carrying <i>E. coli</i> from livestock and food.
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