Study The Gene Expression Of blaoxa23 And blaoxa24 Genes In Imipenem Resistant Acinetobacter baumannii Isolated From Burn Wounds

Abstract

The aim of this study was to identify changes in the gene expression of blaOXA genes in Acinetobacter baumannii, isolated from burn wounds, in response to subinhibitory concentrations of Imipenem. The gene expression of blaOXA genes was conducted by using real-time quantitative PCR assay. Ten isolates were chosen which had high resistance to Imipenem with minimum inhibitory concentrations (MICs) from 16 to >256 μg/ml and also contained the two blaOXA genes 23 and 24. It was found that the highest value of gene expression fold was recorded for the gene blaOXA23 (6.96) in the local isolate K5 in contrast with the Imipenem untreated samples, while the highest value of fold for blaOXA24 gene was 3.68. It was obvious there was a direct proportion between MICs values and folds of gene expression, therefore the increase of antibiotic concentration in the growth medium led to increasing of gene expression. The results of 16S rRNA gene expression, which was used as a reference gene, demonstrated that this gene was well suited as housekeeping gene because of the minimal variations of expression of this gene whether in Imipenem treated and untreated samples. It was concluded that the resistance of A. baumannii to Imipenem was related to the genes blaOXA23 and blaOXA24 but the main role may be due to blaOXA23. The presence of both genes increases the resistance of this species to Imipenem.