ABSTRACT
OBJECTIVE:To observe the relationship between gyrA gene mutations of the clinical isolates of Pseudomonas aeruginosa and quinolone resistance and to evaluate the feasibility of analyzing gyrA gene mutations using PCR-RFLP-SSCP.METHODS:With gyrA gene order of the clinical isolates of Pseudomonas aeruginosa taken as target sequence,gyrA gene mutations in strain ATCC 27853 and 16 clinical isolates of Pseudomonas aeruginosa were analyzed contrastively using PCR,PCR-RFLP,PCR-SSCP,and DNA sequencing.RESULTS:Of the total 8 ciprofloxacin resistant Pseudomonas aeruginosa,6 strains showed single point ACC→ ATC mutation in the gyrA gene at codon 83,leading to amino acid substitution of Thr83→Ile.SacⅡ digestion fragment of the PCR amplified products in gyrA gene was in line with the sequencing results.SSCP showed that the banding patterns of all strains were different from that of strain ATCC 27853 except 2 strains.CONCLUSION:The molecular mechanism of the quinolone resistant Pseudomonas aeruginosa isolated from clinics was manifested as mutations in the gyrA gene at codon 83.The results showed that PCR-RFLP-SSCP is a rapid and accurate method for the detection of basyl variation in gyrA in quinolone resistant Pseudomonas aeruginosa.