ABSTRACT
Objective To analyze levofloxacin resistance in Helicobacter pylori (Hp) and the sequence difference of gyrA gene in levofloxacin resistance and sensitive Hp strains. To explore the function of gyrA gene mutation in the development of levofloxacin resistance Hp strain.Methods From July 2007 to December 2008 in Department of Gastroenterology, Jinhua People hospital of Zhejiang Province, the gastric mucosa from gastroscopy biopsy of chronic gastritis and peptic ulcer patients were cultured in Hp selective medium under microaerobic condition at 37 degrees for three to five days. The Hp strains were isolated and identified by oxidase test, catalase test,urease test and UreA gene detecting. The levofloxacin susceptibility was determined by E-test and then resistance and sensitive strains were screened. The genomic DNA of Hp strains was isolated. The gyrA gene was amplified by PCR and the sequences were analyzed. Results 38 clinical isolated Hp strains were passed the levofloxacin susceptibility E-test, among those the minimum inhibitory concentration (MIC) of 12 strains was over 1.0 μg/ml, the percentage of resistant strain was 31.58%, while the sensitive stains was 68.42%. The gyrA gene sequence result indicated 10 resistant strain with 261, 271 and 272 10 site mutation, 2 strains with C261A mutation, one strain with C261G mutation, two strains with G271A mutation, 2 strains with A272G mutation, 2 strains with C261A,G271T andA272G mutation, 1 strain with C261G and A272G mutation. However, no mutation sites were found in 26 sensitive strains. Conclusion The rate of levofloxacir-resistance in isolated clinical Hp strain was high. The drug-resistance was associated with 261,271 and 272. site mutation of gyrA gene.