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

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Carbapenem-resistant Acinetobacter baumannii; European clone II; Kenya; NDM-1; OXA-23.