J PIRES¹, O.J. BERNASCONI¹, R TINGUELY¹, S KASRAIAN¹, C HAUSER², M HILTY¹, V PERRETEN³, A ENDIMIANI<sup>1

1</sup>Institute for Infectious Diseases, University of Bern, Bern, Switzerland, ²Department of Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland, ³Institute of Veterinary Bacteriology, University of Bern, Bern, Switzerland

Background: Pets represent a reservoir of extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESC-R-Ent) that may increase the risk for owners to be colonized. However, prevalence and risk factors for colonization with ESC-R-Ent in pets are poorly studied. We aimed to study this problem in pets living in Swiss households.Methods: 66 pets of 56 different households were analyzed. Stools were enriched in LB broth with cefuroxime and plated on BLSE, ChromID ESBL and Supercarba plates. Species ID was obtained using the MALDI-TOF MS. Trek panels were used to obtain MICs. Microarray CT103XL and PCR/sequencing were used to characterize bla genes. Clonality was determined by MLST. A questionnaire regarding pets was filled in by owners.Results: The prevalence of intestinal colonization was 9.1%. Past invasive procedures was found to increase the risk of being colonized (OR, 14.6; P<0.05). Other factors (age, previous antibiotic use or hospitalization, raw meat consumption) were not statistically significant. 7 E. coli were recovered from pets, of which 5 were ESBL (2 CTX-M-15 and CTX-M-1/-14, SHV-12) and 2 CMY-2 pAmpC producers. Interestingly, one dog was co-colonized with both CTX-M-15 and CMY-2 producers. Isolates were diverse, each belonging to an individual ST (ST73, ST949, ST963, ST162, ST127, ST1421, ST56). The ESBL diversity was similar to what is seen in colonized humans, whereas clonal diversity was fairly different (only ST73 and ST127 previously reported in humans), indicating that clones circulating among pets are different than those found in humans. However, presence of blaESBLs common in both E.coli from humans and pets suggests transfer of resistance between the different E. coli in both hosts.Conclusions: This is the first study assessing clinical and lifestyle data of pets colonized with ESC-R-Ent. The prevalence in pets is consistent with what is reported in healthy humans living in Switzerland. Since the ESBLs identified in pets are similar to those found in humans, but associated with different STs, a further characterization of the plasmids carrying these resistance genes is essential.
This work was supported by SNF grant No. 153377 to AE