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OXA-23 and ISAba1–OXA-66 class D β-lactamases in Acinetobacter baumannii isolates from companion animals

Ewers, Christa, Klotz, Peter, Leidner, Ursula, Stamm, Ivonne, Prenger-Berninghoff, Ellen, Göttig, Stephan, Semmler, Torsten, Scheufen, Sandra
International journal of antimicrobial agents 2017 v.49 no.1 pp. 37-44
Acinetobacter baumannii, beta-lactamase, carbapenems, clones, cross infection, disease transmission, dogs, genes, minimum inhibitory concentration, monitoring, multilocus sequence typing, multiple drug resistance, pathogens, pets, phenotype, plasmids, polymerase chain reaction, pulsed-field gel electrophoresis, resistance mechanisms, transposons, veterinary clinics, Germany
Acinetobacter baumannii is recognised as a major pathogen of nosocomial infections that frequently show resistance to last-resort antimicrobials. To investigate whether A. baumannii from companion animals harbour carbapenem resistance mechanisms, 223 clinical isolates obtained from veterinary clinics between 2000 and 2013 in Germany were screened for carbapenem-non-susceptibility employing meropenem-containing Mueller–Hinton agar plates. Minimum inhibitory concentration (MIC) data were obtained using the VITEK®2 system. Assignment to international clones (ICs) was done by multiplex PCR or repetitive sequence-based PCR employing the DiversiLab system. Clonality was studied using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Genes encoding carbapenemases and aminoglycoside-modifying enzymes were detected by PCR. In three samples from dogs, carbapenem-resistant A. baumannii carrying the blaOXA-23 gene on plasmids and located on transposon Tn2008 were identified. The isolates belonged to sequence type ST1ᴾ (clonal complex CC1/IC1/pulsotype II) and ST10ᴾ (CC10/IC8/pulsotype IV) according to the Pasteur MLST scheme, and to ST231ᴼˣ (CC109) and ST585ᴼˣ (CC447) following the Oxford scheme. Insertion sequence ISAba1 was identified upstream of blaOXA-66 in 58 A. baumannii isolates. MLST referred them to ST2ᴾ (CC2/IC2/pulsotypes I and III), ST208ᴼˣ, ST350ᴼˣ and ST556ᴼˣ (all CC118), respectively. PFGE suggested nosocomial spread of these highly related strains, which frequently demonstrated a multidrug-resistant phenotype, in one veterinary clinic. These data show that A. baumannii from companion animals reveal resistance determinants and clonal lineages of strains globally emerging in humans. This suggests an interspecies transmission and warrants molecular surveillance of A. baumannii in veterinary clinics to mitigate its further spread.