Clonal Spread of Acinetobacter baumannii Sequence Type 25 Carrying blaOXA-23 in Companion Animals in France.

Acinetobacter baumannii causes life-threatening infections in critically ill patients, with subsequent treatments mostly based on carbapenems. Unfortunately, oxacillinases (OXAs) that hydrolyze carbapenems, especially OXA-23, have dramatically spread in humans and even started to be reported in animals (1–4). As OXA-producing isolates are still rare in nonhuman sources, a comprehensive picture of their occurrence in animals is lacking. We analyzed 41 A. baumannii isolates from nonduplicate diseased animals from 2011 to 2015 in the framework of the French Surveillance Network for Antimicrobial Resistance in Animal Pathogens (RESAPATH; https://www.resapath.anses.fr/) for susceptibility to carbapenems, the presence of blaOXA genes, and clonal relatedness. Identification was based on rpoB gene sequencing (5). According to the CA-SFM/ EUCAST breakpoints (http://www.sfm-microbiologie.org/UserFiles/files/casfm/CASFM2016 _V1_0_FEVRIER.pdf), seven isolates demonstrated high-level resistance to meropenem and imipenem (MICs of 32 g/ml) and were also multidrug resistant (Table 1). PCR screening, performed as previously described (6), demonstrated the presence of blaOXA-23 in the seven isolates. ISAba1 was inserted 34 bases upstream from the starting codon of blaOXA-23. This organization, resembling that of transposons Tn2008B, Tn2006, and Tn2009, provided a 35 (TCGTTA) and 10 (TGACATTAT) extended promoter region for the overexpression of blaOXA-23 (7). Similarly to Tn2008B, no copy of ISAba1 was present downstream of blaOXA-23 in our isolates. According to DNA-DNA hybridization, blaOXA-23 was located on the bacterial chromosome and attempts of conjugation with Escherichia coli K-12 strain J53 (8) did not produce transconjugants on selective medium containing rifampin (250 g/ml) and imipenem (2 g/ml) or ticarcillin (8 g/ml). The seven isolates were clonally related (similarity, 98.8%) according to repetitive-sequence-based PCR performed with DiversiLab (bioMérieux, Marcy l’Etoile, France) (9). Multilocus sequence typing based on the Pasteur scheme (10) assigned the isolates to sequence type 25 (ST25). Remarkably, the isolates were found to be associated with urinary tract infections in pets originating in five departments in two regions (Ile de France and Rhône-Alpes) from 2013 to 2015, for the first time demonstrating the clonal dissemination of OXA-23-producing A. baumannii among companion animals. Three isolates (40293, 41133, and 41134) were recovered from pets attending the same clinic, outlining the occurrence of a small outbreak. The remaining isolates (38208, 40104, 34972, and 41833) originated from unrelated and distant animals, suggesting a nationwide spread of OXA-23Accepted manuscript posted online 31 October 2016 Citation Lupo A, Châtre P, Ponsin C, Saras E, Boulouis H-J, Keck N, Haenni M, Madec J-Y. 2017. Clonal spread of Acinetobacter baumannii sequence type 25 carrying blaOXA-23 in companion animals in France. Antimicrob Agents Chemother 61:e01881-16. https:// doi.org/10.1128/AAC.01881-16. Copyright © 2016 American Society for Microbiology. All Rights Reserved. Address correspondence to Agnese Lupo, [email protected]. LETTER TO THE EDITOR