COLONIZATION OF EXTENDED-SPECTRUM BETA-LACTAMASE-PRODUCING ENTEROBACTERIACAE AMONG ANIMALS IN A VETERINARY HOSPITAL IN ISRAEL

Background: Israel is endemic for beta-lactam resistance due to the production of extended-spectrum beta-lactamase (ESBLs). Companion animals might serve as zoonotic reservoir for ESBL pathogens. We aimed to investigate prevalence and genetic features of ESBL-producing Enterobacteriaceae in hospitalized animals.

Study Design: A prospective study in the Koret-School of Veterinary Medicine was carried out sampling two cohorts: (i) Hospitalized animals with length-of-stay ≥ 72 hours (point prevalence analysis). (ii) Animals screened for rectal colonization on admission. When possible, a second sample was taken 72-hours-post-admission. Rectal swabs from all animals were inoculated onto BHI-broth, streaked onto CHROMagarESBL plates and sub-cultured to obtain pure cultures. ESBL-producing Escherichia coli isolates were further analyzed for phylotyping and ESBL-type grouping by multiplex PCRs.

Results: 95% of 22 hospitalized animals (11-horses, 6-dogs and 5-cats) were colonized with at least one ESBL-producing Enterobacteriaceae. Overall, 59 ESBL-producing isolates were studied: 33 (56%) E. coli, 17 (29%) blue colonies (Klebsiella/Enterobacter/Citrobacter) and 9 (15%) white colonies (Pseudomonas/Acinetobacter). ESBL-producing E. coli isolates belonged to diverse phylotypes: A (49%), B1 (27%), D (21%), and B2 (3%). The most prevalent ESBL was CTX-M-1-type (15/33, 45%). 78% of 28 animals screened on admission (16-horses, 6-dogs, and 6-cats) were colonized with ESBL-producing Enterobactericea. Screening yielded 41 ESBL-producing enteric isolates: 18 (44%) E. coli (phylogroups A, B1 and D- 33.3% each), 15 (36%)-blue colonies, and 8 (20%)-white colonies. Five animals re-sampled 72-hours post admission turned ESBL-positive.

Conclusion: Colonization with ESBL-producing Enterobacteriaceae is endemic among both hospitalized (95%) and on admission animals (78%). These findings demonstrate the potential zoonotic reservoir of ESBL-producing enteric pathogens among animals in the hospital setting and should be further studied to identify risk factors and modes of spread.