Introduction: To investigate prevalence and pattern of antimicrobial resistance among rectal E. coli and oral Staphylococcus spp. isolates from dogs and cats in a Veterinary University Hospital (VUH).

Methods: A total of 160 swabs (80 rectal, 80 oral) for the isolation of E. coli and Staphylococcus spp. were collected between January and October 2018 from small animals in three different areas of our VUH: consultations, general ward (GW), and intensive care unit (ICU). Swabs from GW and ICU were performed both at admission and discharge from the relative area. Data concerning antimicrobial treatment were recorded. Isolated bacteria were identified by 16S rRNA sequencing and tested for antimicrobial sensitivity with disc diffusion method. Nonparametric test was used for comparison. Significance was set at <0,05.

Results: E. coli and Staphylococcus spp. were isolated in 84% and 66% of total samples, respectively. Results showed that 8% of E. coli and 44% of Staphylococcus spp. isolates from consultations were multiple drug resistant (MDR). In GW and ICU, rate of MDR significantly increased from admission to discharge in E. coli (15% to 57%; p=0.009) and had a similar trend in Staphylococcus spp. (39% to 81%; p=0.07). Relative to E. coli isolates from GW, treatment with quinolones was significantly associated with resistance to enrofloxacin (p=0.02). Relative to E. coli from GW and ICU patients, there was a significant association between antimicrobial treatment and MDR (p=0.007) and between treatment with quinolones and MDR (p=0.03). Interestingly, an increase in the rate of resistance to imipenem (4 to 32%; p=0.01) was reported in E. coli isolates, despite its use in our VUH is not allowed. Relative to Staphylococcus spp. treatment with penicillins, during hospitalization in ICU, was significantly (p=0.04) associated with resistance to ampicillin.

Conclusions: High levels of MDR characterized E. coli and Staphylococcus spp. isolates in our VUH and tend to increase during hospitalization. Further studies are required for a wider evaluation of risk factors associated to antimicrobial resistance. Anyway, in order to tackle the spread of the latter, a rationale and prudent use of antibiotics is advocated.