“Roar” of bla(NDM-1) and “silence” of bla(OXA-58) co-exist in Acinetobacter pittii

Acinetobacter pittii 44551 was recovered from a patient with gout combined with tuberculosis and was found to harbor the carbapenemase genes bla(NDM-1) and bla(OXA-58) on two different plasmids pNDM-44551 and pOXA58-44551, respectively. pNDM-44551 displayed high self-transferability across multiple bacterial species, while pOXA58-44551 was likely co-transferable with pNDM-44551 into A. baumannii receipts. pNDM-44551 was a close variant of the previously characterized pNDM-BJ01, and the bla(NDM-1) gene cluster was arranged sequentially as orfA, ISAba14, aphA6, ISAba125, bla(NDM-1), ble(MBL), ΔtrpF, dsbC, tnpR, and zeta. pOXA58-44551 was a repAci9-containing plasmid, and bla(OXA-58) was embedded in a 372F-ISAba3-like-bla(OXA-58)-ISAba3 structure. The mobile genetic platforms of bla(NDM-1) and bla(OXA-58) herein showed some differences from their previously characterized variants. The production of NDM-1 in strain 44551 contributed the majority to its high resistance to carbapenems, while the bla(OXA-58) stayed silent most likely due to the lack of an upstream promoter to drive its transcription. Increased surveillance of Acinetobacter co-harboring bla(NDM-1) (active) and bla(OXA-58) (either active or silent) is urgently needed.