Multidrug-resistant Extended-Spectrum-β-Lactamase-Producing and Plasmid-Mediated AmpC β-Lactamase-Producing Enterobacteriaceae isolated from diseased cats in Southern Italy

The study aimed to evaluate the occurrence of multidrug resistance (MDR) and to characterize beta-lactam resistance mechanisms among Enterobacteriaceae isolates recovered from cats showing clinical signs of various diseases in Southern Italy. Out of n=101 cats, 58.4% had diarrhoea, 30.7% upper respiratory tract disease, 3.9% otitis, 2.9% conjunctivitis, 1% abscess, 2% stomatitis and 1% cystitis. They were European Shorthair, with a median age of 3.7 years (10 months – 12 years). 63.3% lived in shelters, 36.7% were household cats. A total of n= 126 Enterobacteriaceae isolates were tested for susceptibility to n= 8 antimicrobial classes. The most frequent species was Escherichia coli (51.6%), followed by Enterobacter spp. (15.9%), Proteus spp. (10.3 %), Citrobacter spp. (9.5 %) and Providencia spp. (4.8 %). Several MDR profiles were displayed by 54% of strains, with most common resistances to amoxicillin-clavulanic acid (65%), ceftazidime (40.5%), ceftriaxone (41.2%) and cefotaxime (40.5%). Lower resistance rates were displayed to meropenem (23.8%), aztreonam (32.5%), ciprofloxacin (23.8%), amikacin (31.7%), chloramphenicol (24.6%) and sulphamethoxazole-trimethoprim (34%). MDR strains were harboured by 50.5% of cats, mainly affected by diarrhoea and upper respiratory tract disease. After phenotypic identification of ESBL production and PCR for amplification of n= 21 beta-lactamases encoding genes (blaCTX-M, blaSHV, blaTEM, blaOXA-1, blaCIT, blaFOX, blaDHA, blaMIR, blaACT, blaMOX, blaIMP, blaVIM, blaNDM, blaSPM, blaAIM, blaDIM, blaGIM, blaSIM blaKPC, blaBIC,and blaOXA-48), twenty-two MDR isolates were confirmed as ESBL producers by sequencing of bla coding genes, including blaCTX-M-15, 2, 3, 9, blaSHV-2a and blaTEM-1. Eight were AmpC-type beta-lactamases producers (plasmidic CMY-2 group), with four isolates harbouring also blaTEM and blaCTX-M. ESBLs and AmpC-producing isolates were recovered from n=19 cats affected by diarrhoea, upper respiratory tract disease, abscess, otitis, stomatitis and cystitis. Fifty-eight per cent were shelter cat, 42% were household; most (n= 15) were not receiving an antimicrobial treatment at the time of sample collection. Eleven extra-intestinal pathogenic E. coli carrying ESBLs and AmpC genes were identified, belonging to phylogenetic groups B2 and D, and were collected from n= 5 diarrheic cats (n= 3 living in shelter, n= 2 household), n= 1 shelter cat with upper respiratory disease, n= 1 household cat with cystitis and n= 1 shelter cat with cystitis. The results show the dissemination of MDR Enterobacteriaceae in a variety of common defined clinical conditions and in different living conditions among a feline population in Southern Italy. To the best of our knowledge, we report for the first time blaCTX-M-3 harbouring E. coli in companion animals in Europe. The emergence in pets of multidrug-resistant Enterobacteriaceae with ESBL and AmpC determinants poses serious challenges in companion animal therapy and raises concerns for possible bi-directional transmission between pets and humans.