RESUMEN
The objective of this study was to identify the main extended-spectrum beta-lactamase (ESBL)-producing bacteria and to detect the frequency of the major genes responsible to trigger this resistance in hospitalized animals. We collected 106 rectal swabs from cats (n = 25) and dogs (n = 81) to detect ESBL-producing isolates. ESBL-positive samples were submitted to the antimicrobial susceptibility test, and polymerase chain reaction was performed to detect TEM, SHV, and CTX-M genes from different groups. We observed that 44.34% of these samples (11 cats and 36 dogs) were positive for ESBL-producing bacteria. Thirteen animals (27.66%-seven cats and six dogs) were hospitalized for elective castration (healthy animals). Only a single animal was positive for ESBL-producing bacteria at hospital admission (the animal also showed an ESBL-positive isolate after leaving the hospital), whereas 11 were positive only at the hospital discharge. Of the 73 ESBL-producing isolates, 13 were isolated from cats (8 sick and 7 healthy) and 60 from dogs (53 sick and 7 healthy). Escherichia coli was the major ESBL-producing bacterium isolated (53.42%), followed by Pseudomonas aeruginosa (15.07%), Salmonella sp., and Proteus mirabilis (5.48% each one). Antimicrobial resistance profile of ESBL-producing isolates showed that 67 isolates (91.78%) were resistant to 3 or more antibiotic classes, while 13 of them (17.81%-2 healthy cats and 11 sick dogs) were resistant to all tested antimicrobial classes. The blaTEM gene exhibited the highest frequency in ESBL-producing isolates, followed by the blaCTX-M group 8/25, blaCTX-M group 1 and blaCTX-M group 9 genes. These results are useful to assess the predominance of ESBL-producing isolates recovered from dogs and in cats in Brazil. Consequently, we draw attention to these animals, as they can act as reservoirs for these microorganisms, which are the major pathogens of nosocomial infections worldwide.