HIGH PREVALENCE OF MULTIDRUG RESISTANCE IN CANINE AND HUMAN UROPATHOGEN E. COLI

The aim of the present study was to analyze the prevalence of MDR-UPEC isolated from canine and human urinary samples. A retrospective study was carried out to evaluate antibiotic resistance patterns of E. coli isolated from urines of dogs and humans with uncomplicated cystitis between March 2013 and March 2014. 55 Canine and 85 human isolates were processed. Automated antimicrobial susceptibility system was used to perform species identification and susceptibility tests on a panel of 21 antibiotics. Strains resistant to at least three classes of antibiotics were defined as MDR. Differences in resistance between dogs and humans were compared by χ2 test. The significant limit was set at P<0.05. In dogs and humans the highest % of resistance was observed for tetracycline (100% both), norfloxacin (38 and 26%, respectively), piperacillin (35 and 42%) and ampicillin (31 and 45%). Resistance to other antibiotics was below 30% in both species. Susceptibility to fosfomycin, imipenem, meropemen, nitrofurantoin was between 98 and 100%. Both in dogs and humans about 35% isolates were MDR. However, while in humans the 76% of strains was resistant to 3-4 classes of antibiotics and only 3% to 7-8 classes, in dogs the 37 % of strains was resistant to 7-8 classes. For cephalosporins and amoxicillin/clavulanic acid a significantly higher proportion of resistance in canine strains over human strains was detected (P<0.01). The results highlight a high prevalence of MDR-UPEC both in dogs and humans, more specifically our data suggest a high rate of resistance against the antimicrobial agents more commonly prescribed in human and veterinary medicine (e.g. fluoroquinolones). Although in vitro carbapenems show high efficacy, the administration of last-line antimicrobials should be discouraged. In contrast, nitrofurantoin still represents a valid therapeutic option for infections caused by UPEC, especially in empirical treatment. However, in veterinary clinical practice it implies off label drug use. The fact that in dogs 37% of isolates were resistant to more than 5 classes of antibiotics strenghtens the need to perform the necessary diagnostics before starting antimicrobial therapy especially for canine urinary tract infections. In this regard that overuse of antimicrobial agents is an important risk factor for emergence of bacterial resistance.