Genomic Analysis of Acinetobacter baumannii Isolates Carrying OXA-23 and OXA-58 Genes from Animals Reveals ST1 and ST25 as Major Clonal Lineages.

Acinetobacter baumannii is increasingly being recognized as a relevant pathogen for animals with a putative zoonotic impact. This study aimed at identifying and characterizing carbapenemase-producing A. baumannii from animals. Among 503 A. baumannii , mainly isolated from dogs/cats (75.7%) between 2013 and 2018, 42 isolates from 22 veterinary clinics (VCs) harboured bla OXA-58 ( n = 29) or bla OXA-23 ( n = 13). The bla OXA-58 gene was located on plasmids (11.4-21.1 kb) within different genetic surroundings (patterns A-D). Bla OXA-23 was embedded in Tn 2006 on the chromosome ( n = 4; pattern a) or Tn 2008 on plasmids ( n = 9; 41.2-71.3 kb; patterns b-e). The predominant IC1-ST1 P -OXA-58 (66.7%; 96.4% cgMLST complex type (CT)-1808) was disseminated among 11 VCs in Germany. Resistance islands Aba R3-like ( n = 15) and Aba R10 ( n = 1) have emerged among ST1-isolates since 2016. IC7-ST25 P -OXA-23 isolates (21.4%) occurred in seven VCs in Germany, France and Italy and differed in their resistance gene patterns from those of OXA-58 isolates. They were separated into six CTs, basically according to their regional origin. Other STs observed were ST10, ST578 and ST602. In conclusion, OXA-23 and OXA-58 were linked with ST1 and ST25, two globally distributed lineages in humans. The suggested transmission of certain lineages within and among VCs together with the acquisition of Aba R islands hints at a successful dissemination of multidrug-resistant strains in the VC environment.