Worldwide dissemination of acquired carbapenem-hydrolysing class D β-lactamases in Acinetobacter spp. other than Acinetobacter baumannii

Abstract The aim of this study was to identify acquired OXA-type carbapenemases in Acinetobacter spp. other than Acinetobacter baumannii . From a total of 453 carbapenem-susceptible and -resistant Acinetobacter isolates collected worldwide, 23 were positive for bla OXA genes by multiplex PCR. These isolates were identified as Acinetobacter pittii ( n  = 18), Acinetobacter nosocomialis ( n  = 2), Acinetobacter junii ( n  = 1) and Acinetobacter genomic species 14TU/13BJ ( n  = 2). The bla OXA genes and associated insertion sequence (IS) elements were sequenced by primer walking. In 11 of these isolates, sequencing of the PCR products revealed that they were false-positive for bla OXA . The remaining 12 isolates, originating from Europe, Asia, South America, North America and South Africa, harboured OXA-23 ( n  = 4), OXA-58 ( n  = 5), OXA-40-like ( n  = 1) and OXA-143-like ( n  = 1); one A. pittii isolate harboured both OXA-23 and OXA-58. IS elements were associated with bla OXA in 10 isolates. OXA multiplex PCR showed a high degree of false-positive results (47.8%), indicating that detection of bla OXA in non- baumannii Acinetobacter spp. should be confirmed using additional methods.