Biomedical Research

The objective of this study was to evaluate the incidence of multidrug resistance nodulationcell division pump (RND pump) genes and integrons in multidrug-resistant Acinetobacter baumannii isolated from in-patients in Malaysian hospitals. A total of 43 clinical isolates of A. baumannii were examined. All samples were found to be 100% resistant to ampicilin (n=43), ceftriaxone (n=43) and cefuroxime (n=43), followed by augmentin (n=40) and chloramphenicol (n=40) (93%). Local isolates of A. baumannii were also found to develop resistance towards the new class of antibiotic-tigecycline (58.14%). The presence of adeA, adeIJ, adeY RND efflux system genes and integrase gene was assessed by polymerase chain reaction (PCR). adeY was not detected in any of the samples. However, majority of the isolates (62.7%, n=27) carried adeA and adeIJ genes, but not integrase gene. Interestingly, the isolates harboring these genes also showed the highest level of resistance toward all antibiotics. In addition, 13.9% of the isolates (n=6) did not carry any of the RND genes; while class 1 integrons were only detected in three isolates (7%, n=3), in which all harbored the same gene cassette aacA4-catB8-aadA1. This suggests the possibility of higher usage of RND efflux pump genes in antibiotic resistance mechanism for local A. baumannii compared to integron genes. Besides, the co-presence of adeA and adeIJ genes also reveals their possible relationship for antimicrobial resistance in A. baumannii isolates.

Author(s): Sue-Bee Kor, Beatrice-Sing-Yieng Tou, Cornelius-Kwang-Lee Chieng, Michele-Sook-Yuin Hiew, Choy-Hoong Chew
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