Abstract
Resistance of bacteria to 3rd generation cephalosporins mediated by beta-lactamases (ESBL, pAmpC) is a public health concern. In this study, 1517 phenotypically cephalosporin-resistant E. coli were screened for the presence of blaSHV genes. Respective genes were detected in 161 isolates. Majority (91%) were obtained from poultry production and meat. The SHV-12 beta-lactamase was the predominant variant (n = 155), while the remaining isolates exhibited SHV-2 (n = 4) or SHV-2a (n = 2). A subset of the isolates (n = 51) was further characterized by PCR, PFGE, or whole-genome sequencing and bioinformatics analysis. The SHV-12-producing isolates showed low phylogenetic relationships, and dissemination of the blaSHV-12 genes seemed to be mainly driven by horizontal gene transfer. In most of the isolates, blaSHV-12 was located on transferable IncX3 (~43 kb) or IncI1 (~100 kb) plasmids. On IncX3, blaSHV-12 was part of a Tn6 composite transposon located next to a Tn3 transposon, which harbored the fluoroquinolone resistance gene qnrS1. On IncI1 plasmids, blaSHV-12 was located on an incomplete class 1 integron as part of a Tn21 transposon. In conclusion, SHV-12 is widely distributed in German poultry production and spreads via horizontal gene transfer. Consumers are at risk by handling raw poultry meat and should take care in appropriate kitchen hygiene.
Highlights
Resistance of Enterobacteriaceae to third generation cephalosporins (3rd GC) is mostly mediated by the production of extended spectrum beta-lactamases (ESBLs)
Resistance mediated by ESBLs is mostly associated with mobile genetic elements, which substantially enhances the spread of these determinants
Isolates phenotypically resistant to 3rd GC obtained from the German monitoring on antimicrobial resistance were investigated by multiplex real-time PCR targeting the most frequent ESBL/pAmpC genes for the presence of blaSHV [16]
Summary
Resistance of Enterobacteriaceae to third generation cephalosporins (3rd GC) is mostly mediated by the production of extended spectrum beta-lactamases (ESBLs). Third GCs are commonly used in human medicine due to their broad-spectrum activity against gram-positive and -negative bacteria and comparatively low side effects [1]. According to the “One Health” concept, the different sectors are in close contact and a multi-directional transmission of (resistant) bacteria between them will take place in the absence of strict control measures. Resistance mediated by ESBLs is mostly associated with mobile genetic elements (i.e., plasmids, integrons, transposons), which substantially enhances the spread of these determinants. Some resistances are more associated with a specific niche and the prevailing conditions than with other ecosystems [4]. Beta-lactamases is a collective for a broad variety of different enzyme groups containing hundreds of specific variants of which
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