Class 1 integron element in Thai Acinetobacter baumannii reveals a linkage to the European clone I

BACKGROUND: Class 1 integron element is innate to most of the multidrug resistant Acinetobacter baumannii and its spread is common among international clones worldwide. The aim of this study was to document the presence of bla VEB-1 harboring class 1 integron element and its gene cassettes in Thai A. baumannii in relation to A. baumannii European clone I, AYE strain. MATERIALS AND METHODS: Thirty seven carbapenem resistant A. baumannii isolates identified in routine microbiology laboratory of Siriraj Hospital, Bangkok were studied. The dot blot hybridization was performed to detect class 1 integron element integrase gene. PCR was used to amplify bla VEB-1 , arr2 , cmlA , bla OXA-10 resistance cassettes, and variable region of class 1 integron element. bla VEB-1 gene was localized by southern blot hybridization. RESULTS: The prevalence of class 1 integron element was 86.48% in the isolates studied. The bla VEB-1 was present in 7 isolates however the location of bla VEB-1 gene was different in different isolate. Four isolates (Ab03-168, Ab04-28, Ab08-20, and Ab08-22) harbored calss 1 integron element variable region sized 5.5 kb as described in strain AYE. However, bla VEB-1 was only amplified from Ab03-168. The cassette organization in this isolate was 5’CS-aadB -bla VEB-1 - arr2 - cmlA-bla OXA- 10 -aadA1-3’CS. The class 1 integron element similar to the element identified in genomic resistance island, AbaRI of European clone I, AYE was identified in Thai A. baumannii . CONCLUSIONS: bla VEB-1 harboring class 1 integron element with minor cassette variation was identified in Thai A. baumanni isolate which might suggest the spread of this resistant cassette or the spread of the European clone I in Thailand. Monitoring of the global spread of multi-resistant A. baumannii is mandatory to control the spread of resistant genes and this multi-resistant pathogen. DOI: http://dx.doi.org/10.3126/ijim.v1i1.6715 Int J Infect Microbiol 2012;1(1):24-28