Mutation in gyrA and parC Genes of Ciprofloxacin-resistant Isolates of Acinetobacter baumannii / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To study the correlation between mutations of gyrA and parC genes and ciprofloxacin-(resistant) clinical isolates of Acinetobacter baumannii from Chengdu.METHODS The genes of gyrA and parC DNA in 28 ciprofloxacin-resistant and 2 ciprofloxacin-susceptible isolates of A.baumannii were amplified by PCR and then analyzed by restriction fragment length polymorphism(PCR-RFLP) and DNA sequencing.(RESULTS) Hinf Ⅰ digestion of the gyrA gene products of susceptible isolates(generated) two fragments,but resistant isolates(generated) one fragment.The parC gene products generated 2 fragments.DNA sequencing of 5 resistant isolates revealed mutations in gyrA gene that resulted in amino acid substitutions Ser83→Leu and Ala88→Thr,especially,Ser83 point mutation accounting for the disappearance of sequence of Hinf Ⅰ.There was not any mutation in(gyrA) of 1 susceptible isolate;the substitution of Ser108→Ile in parC(gene) of 1 susceptible and 1 resistant isolates were identified,the remaining four isolates had more nosense mutations.CONCLUSIONS Compared with parC gene mutations,(gyrA) gene mutations of A.baumannii appears to be the main molecular mechanism responsible for ciprofloxacin resistance.The high-level ciprofloxacin resistance in A.baumannii probably needs a variety of mutations.