Antimicrobial resistance of Escherichia coli isolates from canine urinary tract infections

This study determined theantimicrobial resistance profiles of Escherichia coli isolates from dogswith a presumptive diagnosis of urinary tract infection (UTI). Urine samples from 201 dogswith UTI diagnosed through clinical examination and urinalysis were processed forisolation of Escherichia coli. Colonies from pure cultures wereidentified by biochemical reactions (n=114) and were tested for susceptibility to 18antimicrobials. The two most frequent antimicrobials showing resistance in UrinaryE. coli isolates were oxytetracycline and ampicillin. Among theresistant isolates, 17 resistance patterns were observed, with 12 patterns involvingmultidrug resistance (MDR). Of the 69 tetracycline-resistant E. coliisolates, tet(B) was the predominant resistance determinant and wasdetected in 50.9% of the isolates, whereas the remaining 25.5% isolates carried thetet(A) determinant. Most ampicillin and/or amoxicillin-resistantE. coli isolates carried bla_TEM-1 genes.Class 1 integrons were prevalent (28.9%) and contained previously described gene cassettesthat are implicated primarily in resistance to aminoglycosides and trimethoprim(dfrA1, dfrA17-aadA5). Of the 44 quinolone-resistantE. coli isolates, 38 were resistant to nalidixic acid, and 6 wereresistant to nalidixic acid, ciprofloxacin and enrofloxacin. Chromosomal point mutationswere found in the GyrA (Ser83Leu) and ParC (Ser80Ile) genes. Furthermore, theaminoglycoside resistance gene aacC2, the chloramphenicol resistant genecmlA and the florfenicol resistant gene floR were alsoidentified. This study revealed an alarming rate of antimicrobial resistance amongE. coli isolates from dogs with UTIs.