J PIRES¹, O.J. BERNASCONI¹, S KASRAIAN¹, R TINGUELY¹, C HAUSER², A RAUCH², H FURRER², 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

Background. The intestinal microbiota of HIV-positive individuals has been shown to be in a state of dysbiosis. This might influence the susceptibility of this population to develop specific gastrointestinal diseases. However, nothing is known about the influence of HIV infection on the intestinal colonization with extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESC-R-Ent). In this study, we aimed to address this research question.
Methods. Sixty-seven HIV-positive volunteers followed by Bern University Hospital have been enrolled (March 2015 to January 2016). Stools of individuals and their pets (if any) were enriched overnight in LB broth with cefuroxime and plated on BLSE, ChromID ESBL, and Supercarba selective plates. At least five ESC-R-Ent colonies per sample were recovered. Species ID was obtained with the MALDI-TOF MS. Microarray CT103XL and PCR/DNA sequencing were used to characterize the bla genes. Clonality was assessed by MLST. An epidemiological questionnaire was obtained from the volunteers.
Results. The prevalence of intestinal colonization was 3% (n=2). All ESC-R-Ent recovered were E. coli. Interestingly, one of the volunteers was colonized with two different E. coli clones: a CTX-M-15-producing ST405 and a CTX-M-1-producing ST127. The other one was colonized with a CTX-M-1-producing ST410. All these STs are usually defined as hyperepidemic clones (HiRC). Remarkably, the individual colonized with two clones is the only case where the pets living within the same household were also colonized with ESC-R-Ent. In particular, one of the cats was colonized with the same CTX-M-1-producing ST127 clone identified in the human, while the other cat with unrelated clone (ST73) and ESBL (CTX-M-15).
Conclusions. The prevalence of intestinal colonization with ESC-R-Ent in the Swiss HIV-population is low. Nevertheless, ESBLs and clones identified resemble those frequently associated with HiRC causing serious infections. Moreover, the identification of the same clone within the same household highlights the potential silent spread of these pathogens between pets and humans in close contact.

This work was supported by SNF grant No. 153377 to AE