First report of NDM-1-producing Acinetobacter baumannii in East Africa

The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) was observed in a Kenyan hospital from 2009 to 2010. Further investigation of the dissemination of CRAB isolates and the molecular characterization of associated resistance determinants were therefore performed.

Antibiotic susceptibilities were determined by broth microdilution and Etest. Metallo-β-lactamases were detected by Etest method. Clonal relationships were studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). β-Lactam and aminoglycoside resistance determinants and the clonal relatedness to widespread European clones were studied by PCR and sequencing.

Sixteen CRAB isolates from 10 patients possessed six pulsotypes; half of the isolates belonged to the European clone II (ECII) lineage. ECII strains were typed as MLST sequence type 2 (ST2) and ST109, and non-ECII strains as ST25 and ST113. All isolates harbored ISAba1-blaOXA-23, blaOXA-51-like, blaADC, and class 1 integron, including one that also harbored blaNDM-1. ADC-57 and two integron cassettes (arr-2-cmlA5 and aadB-aadA2-cmlA6-aadA15) were newly-identified. Non-ECII isolates, designated non-ECII clone, carried armA and integron cassette arr-2-cmlA5.

Two distinct clones of CRAB--ECII and non-ECII epidemic clones--were disseminated in Kenya. The concomitance of ISAba1-blaOXA-23 was the major mechanism contributing to CRAB. The first identification of ECII CRAB and New Delhi metallo-β-lactamase 1 (NDM-1) extensively drug-resistant A. baumannii in East Africa is of concern.