Biomedical Research

A total of 62 Acinetobacter baumannii isolates including 29 imipenem resistant, 23 imipenem susceptible and 10 environmental isolates were analyzed based on integron and integron gene cassette array (I-GCA) PCR and DNA sequences. Two types of class 1 integron were found based on their cassette arrays. The integron class 1 with a 2.6 kb size (Int1-A ) has the cas-sette order of aaC(6’)-Im followed by another gene cassette aadA1 disrupted by IS26 trans-posase, while the another class 1 integron with 2.8 kb size (Int1-B) has the gene cassette order of aacC1 followed by orfX, orfX’, IS 26 transposase and aadA1. PCR mapping detect the dis-tribution of such integron types within the isolates. Integron gene cassette array PCR (I-GCA PCR) typing gave 20 profiles while PFGE typing gave 18 profiles with 16 types and 2 sub-types. The major profile I of I-GCA PCR equivalent to profile A of PFGE was the dominant profile covering most of the clinical and environmental imipenem resistant isolates while the second largest profile XII of I-GCA PCR or profile M of PFGE was found in the imipenem susceptible isolates. Both integron types Int1-A and Int1-B were mostly restricted to imipenem resistant outbreak strains of the major profile I of I-GCA PCR or profile A of PFGE. I-GCA PCR based typing gave similar result to that of PFGE by sharing all the imipenem resistant strains of distinct profile I of I-GCA PCR in the profile A of PFGE which was responsible for the present A. baumannii outbreak. These results indicate that I-GCA PCR alone or coupled with other typing method would be a rapid tool for epidemiological study for bacteria that bear integron.

Author(s): Bidur Prasad Chaulagain , Dipendra Raj Pandeyab, Gyun-Yeol Ahn , Dong-Min Kim, Jong-Hee Shin, Joong-Ki Kook, Sung-Heui Shin, Dae-Soo Moon , Sook Jin Jang
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