Characterization of <i>E. coli</i> Isolates Producing Extended Spectrum Beta-Lactamase SHV-Variants from the Food Chain in Germany

• Main Authors: Alexandra Irrgang, Ge Zhao, Katharina Juraschek, Annemarie Kaesbohrer, Jens A. Hammerl
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Series: Microorganisms
• Subjects: ESBL; SHV-12; SHV-2; food chain; IncX3; IncI1
• Online Access: https://www.mdpi.com/2076-2607/9/9/1926

Resistance of bacteria to 3^rd generation cephalosporins mediated by beta-lactamases (ESBL, pAmpC) is a public health concern. In this study, 1517 phenotypically cephalosporin-resistant <i>E. coli</i> were screened for the presence of <i>bla</i>_SHV 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 (<i>n</i> = 155), while the remaining isolates exhibited SHV-2 (<i>n</i> = 4) or SHV-2a (<i>n</i> = 2). A subset of the isolates (<i>n</i> = 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 <i>bla</i>_SHV-12 genes seemed to be mainly driven by horizontal gene transfer. In most of the isolates, <i>bla</i>_SHV-12 was located on transferable IncX3 (~43 kb) or IncI1 (~100 kb) plasmids. On IncX3, <i>bla</i>_SHV-12 was part of a Tn6 composite transposon located next to a Tn3 transposon, which harbored the fluoroquinolone resistance gene <i>qnrS1</i>. On IncI1 plasmids, <i>bla</i>_SHV-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.