ABSTRACT
OBJECTIVE To study the differences of quinolones-resistant determining region(QRDR) in DNA gyrase A(gyrA) subunit between drug-resistant Klebsiella pneumoniae induced by fluoroquinolone in vitro and strains isolated from clinical isolates.Furthermore,to reveal the relation between different QRDR gene mutations and drug-resistance. METHODS Ten sensitive K.pneumoniae strains were selected and induced into drug-resistant strains by ciprofloxacin.The QRDR in gyrA by polymerase chain reaction(PCR) was amplified and compared their DNA sequences with clinically isolated quinolone-resistant K.pneumoniae. RESULTS We had found several gene mutations of QRDR in fluoroquinolone-resistant K.pneumoniae induced by ciprofloxacin,including Ser 83(TCC)→Phe(TTC) and Ile(ATC);and Gln106(CAG)→Leu(CTG).And the alteration of Gln106(CAG)→Leu(CTG) was a new discovery. CONCLUSIONS There are gene mutations of QRDR in fluoroquinolone-resistant K.pneumoniae induced by ciprofloxacin.The mutation of Ser 83(TCC) and Gln106(CAG) is probably the molecular basis of inducing drug-resistant strains.