Drug Resistance Analysis of Pseudomonas aeruginosa in Intensive Care Unit and Molecular Mechanism of Its Resistance to Fluoroquinolones / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To study the Pseudomonas aeruginosas drug resistance in intensive care unit and its fluoroquinolone-resistant molecular mechanism,and provide scientific basis for rational employment of antibiotics in clinic. METHODS E test was used to determine the minimal inhibitory concentrations(MIC) of 13 antibiotics against 83 P. aeruginosa strains. Twenty-eight fluoroquinolone-resistant strains were selected with standard sensitive strain-ATCC27853 as control. The quinolone resistance-determining region(QRDR)of the gyrA and parC genes was amplified by PCR and sequenced. RESULTS The positive rate of P. aeruginosa in sputum specimen was the highest from 83 strains (71.08%). gyrA Genes of all resistant strains had an ACC to ATC mutation in codon 83,leading to the amino acid substitution of threonine for a an isoleucine and 11 high level resistant strains also showed a GAC to GGC mutation in codon 87,leading to the substitution of an aspartic acid a glycine for. In addition,14 resistant strains also had an TCG to TTG mutation in codon 87 of parC gene,leading to the amino acid substitution of a serine for a leucine. We didn't find parC gene mutation existing independent in fluoroquinolone-resistant P. aeruginosa. CONCLUSIONS Meropenem remains highly active against P. aeruginosa. But the abuse of imipenem and other fluoroquinolones leads to rise in their drug-resistance rate. Fluoroquinolone-resistance has increased rapidly,the mechanism of resistance is gene mutant. It displayed that gyrA and parC gene mutation is associated with fluoroquinolone resistance.