Dissemination of Carbapenem-Resistant Acinetobacter baumannii Strains Carrying the bla_GES, bla_NDM and bla_OXA23 in Morocco

Background: Acinetobacter baumannii is a microorganism which has been classified by the World Health Organization in the list of the bacterial strains that pose the biggest danger to human health. This study was performed to determine the susceptibility profile to carbapenems and to detect carbapenemases production in 111 A. baumannii isolates. Among these 30 are environmental isolates and 81 are from the three major hospitals in Morocco. Methods: All strains of A. baumannii were tested against diverse antimicrobial agents (13 antibiotic drugs) by the agar diffusion test. Minimum inhibitory concentration (MIC) of imipenem on carbapenem-resistant strains (CRAB) was determined by the E-test technique. Simple phenotypic tests were used to detect carbapenemases and metallo-β-lactamases (MBLs) production including the modified Hodge test, EDTA test, and the cloxacillin test. The presence of carbapenemases-encoding resistance genes of CRAB strains was examined using polymerase chain reaction (PCR). Results: Carbapenem resistance was observed in 23 clinical Acinetobacter isolates showing dissemination of the multiresistance profile. Molecular biology techniques indicated that all these strains encoded the naturally occurring bla_OXA-51-like gene and were proved as A. baumannii. The bla_OXA-23 gene was detected in 16 strains (69.6%). The metallo-β-lactamase bla_NDM gene was detected in five isolates (21.7%). GES-type carbapenemases were found in 15 strains, the existence of three classes of carbapenemases (bla_GES, bla_NDM, and bla_OXA-23) was detected in three strains, while none of the CRAB isolates contained the bla_OXA-58, bla_OXA-24, bla_VIM, bla_OXA-48 or bla_KPC encoding genes. Conclusions: This study established baseline proof of three classes of carbapenemases producing A. baumannii in Morocco, showing the important role of surveillance in controlling their spread.