Clinically Relevant <i>Escherichia</i><i>coli</i> Isolates from Process Waters and Wastewater of Poultry and Pig Slaughterhouses in Germany

• Main Authors: Mykhailo Savin, Gabriele Bierbaum, Judith Kreyenschmidt, Ricarda Maria Schmithausen, Esther Sib, Silvia Schmoger, Annemarie Käsbohrer, Jens Andre Hammerl
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Microorganisms
• Subjects: <i>E. coli</i>; ExPEC; UPEC; virulence; MDR; resistance
• Online Access: https://www.mdpi.com/2076-2607/9/4/698

<i>Escherichia coli</i> is frequently associated with multiple antimicrobial resistances and a major cause of bacterial extraintestinal infections in livestock and humans. However, data on the epidemiology of (i) multidrug-resistant (MDR) and (ii) extraintestinal pathogenic <i>E. coli</i> (ExPEC) in poultry and pig slaughterhouses in Germany is currently lacking. Selected <i>E. coli</i> isolates (<i>n</i> = 71) with phenotypic resistance to cephalosporins from two poultry and two pig slaughterhouses expressing high MDR rates (combined resistance to piperacillin, cefotaxime and/or ceftazidime, and ciprofloxacin) of 51.4% and 58.3%, respectively, were analyzed by whole-genome sequencing. They constituted a reservoir for 53 different antimicrobial resistance determinants and were assigned various sequence types, including high-risk clones involved in human infections worldwide. An ExPEC pathotype was detected in 17.1% and 5.6% of the isolates from poultry and pig slaughterhouses, respectively. Worryingly, they were recovered from scalding water and eviscerators, indicating an increased risk for cross-contaminations. Uropathogenic <i>E. coli</i> (UPEC) were detected in the effluent of an in-house wastewater treatment plant (WWTP) of a poultry slaughterhouse, facilitating their further dissemination into surface waters. Our study provides important information on the molecular characteristics of (i) MDR, as well as (ii) ExPEC and UPEC regarding their clonal structure, antimicrobial resistance and virulence factors. Based on their clinical importance and pathogenic potential, the risk of slaughterhouse employees’ exposure cannot be ruled out. Through cross-contamination, these MDR <i>E. coli</i> pathotypes may be introduced into the food chain. Moreover, inadequate wastewater treatment may contribute to the dissemination of UPEC into surface waters, as shown for other WWTPs.