Carbapenem-hydrolyzing oxacillinase in high resistant strains of Acinetobacter baumannii isolated from India

► Oxacillinase with pI ≈ 8.5 was found in very high resistant strains of Acinetobacter baumannii. ► Oxacillinase (30 kDa), OXA-51 was confirmed by PCR and LC-MS/MS. ► Functional motifs of class D and serine β-lactamase are conserved in OXA-51. ► OXA-51 seems to play a role in emergence of carbapenem resistance in A. baumannii.