Detection of genetic variation of DNA gyrase encoding fluroquinolone-resistant Acinetobacter baumannii / Mohamad Dzulhilmi Mohamad Kamarulzaman

Mutations of the gyrA gene have been reported to contribute to Acinetobacter baumannii resistance towards quinolones. This study investigates the variation of DNA sequences of gyrA gene in 2 different isolates of A.baumannii which were the resistant and susceptible strains. The main aim of this project is to determine the genetic variation that encode resistance towards fluoroquinolones. In this study, primers that allow amplification of the region spanning gyrA was designed. The amplicons were amplified and subsequently purified before sequencing to determine the DNA sequences of the isolates. From bioinformatics analysis, there was a sequence change from cytosine to thymine in resistant strain of A.baumannii. The nucleotide change caused a change in amino acid codon from Serine to Leucine at position 21. Serine is hydrophilic in properties while Leucine are hydrophobic. Quinolones drugs having hydrophilic properties probably cannot bind to receptor due to hydrophobic changes. The mutation has probably caused the underlying resistance towards quinolones shown by the A.baumannii.