Retrospective analysis of antibacterial resistance among uropathogen Escherichia coli in a veterinary teaching hospital (Italy, 2014-2019)

Background: Urinary tract infections (UTIs) often require long follow-up periods and repeated antimicrobial therapies that can lead to the onset of antimicrobial-resistance. Escherichia coli is the most frequent bacterium involved in uncomplicated UTIs in pet animals in which treatment is sometimes threatened by the steady increase in the number of strains bearing concurrent resistance to various antimicrobial agents. The study aimed to report the variation of antibacterial resistance of urinary pathogen E. coli (UPEC) isolated from pets in a veterinary teaching hospital, North Italy (Turin) during a 5-and-a-half-year period (2014-2019). Materials/methods: This retrospective study was carried out on E. coli strains (n= 219) collected from dogs (n=139) and cats (n=80) with UTI. Each strain was tested to 18 antibiotics belonging to 8 categories: aminoglycosides, carbapenems, folate pathway inhibitors, not-extended spectrum cephalosporins: 1st and 2nd generation, extended spectrum cephalosporins: 3rd and 4th generation, penicillins, penicillins + β-lactamase inhibitors, quinolones, following Kirby-Bauer method and interpreted according to the EUCAST guidelines. Isolates were classified as MDR (multidrug-resistant), XDR (MDR susceptible to only one or two antibiotic categories) and PDR (resistant to all agents tested). Data were analyzed using χ2 test, Pearson’s correlation among years and variance-weighted least-square regression models with STATA 15.1, choosing a significance level of α=0.05. Results: Out of 219 UPEC, 114 (52.05%) of them were MDR, of which 37 were XDR and 1 was PDR. Increasing resistance among years was seen for 4 out o 8 classes of antimicrobial agents. An overall increase in MDR proportion (coeff. = 0.074; 95CI 0.038- 0.110), and in the number of concurrent resistances (coeff. = 0.297; 95CI 0.126-0.467) were assessed. A significative difference in the baseline level of resistances and the rising of them was observed between dogs and cats. Conclusions: Approximately half of isolated strains were MDR (52.05%), but they came all from clinically ill patients, which might suggest that the prevalence in the general pet population is lower. Nevertheless the upward trend of antimicrobial resistance of UPEC to various antibiotics, the rise in the amount of concurrent resistances and the presence of XDRs and a PDR strain, poses serious public health issues.