Detection of multidrug resistance and extended-spectrum/plasmid-mediated ApmC beta-lactamase genes in Enterobacteriaceae isolates from diseased cats in Italy

Objectives: The aim of this study was to determine the antimicrobial susceptibility of Enterobacteriaceae isolated from cats affected by diseases commonly encountered in practice, and to characterize the third-generation cephalosporin-resistance (3CG) molecular mechanisms involved. Methods: Clinical samples were collected from cats (n=100) affected by gastrointestinal disease (GID, with diarrhoea n=58), upper respiratory tract disease (URTD, n=31) and other clinical conditions (n=11). Bacterial susceptibility testing to eight antimicrobial classes was performed. -lactamases genes were identified by PCR and nucleotide sequencing. Results: A total of n=125 Enterobacteriaceae were isolated from n= 90 cats. Escherichia coli was the most frequently isolated species (65/125), followed by Enterobacter spp. (20/125), Proteus spp. (13/125) and Citrobacter spp. (12/125). Overall, the higher frequency of resistance was against amoxicillin-clavulanic acid (61.3%), trimethoprimsulfamethoxazole (33.6%) and cefotaxime (32.8%). Thirty-six percent of the isolates (45/125) were resistant to 3GC. Out of these isolates 34 were tested by PCR and nucleotide sequencing and 23 were confirmed as encoding -lactamase genes. Fourteen 3GC resistant isolates harboured Extended-spectrum Β-lactamases (ESBLs) belonging to CTX-M- 1 group (n=12, 2 of which were CTX-M-79), CTX-M-2 (n=1) and CTX-M-9 (n=1), SHV-12 (n=1) and TEM-92 (n=1). Nine isolates had CMY-2 pAmpC - lactamases. Thirty-one percent (39/125) of the isolates were multidrugresistant (MDR) and were isolated from the 34% (31/90) of cats. Conclusions and relevance: A high frequency of MDR and ESBL/pAmpC Β-lactamase-producing Enterobacteriaceae were detected among bacteria isolated from a feline population in Southern Italy with a variety of common clinical conditions. To the best of knowledge, we describe for the first time the isolation of MDR Β-lactamase-producing Enterobacteriaceae in cats affected by URTD and the first detection of CTX-M-79 and TEM-92 genes in isolates from companion animals. ESBLproducing Enterobacteriaceae pose limitations in companion animals' therapeutic options and raises concerns regarding the bi-directional transmission between pets and humans.