| Objectives:Helicobacter pylori (H.pylori) chronic infection remains a problem in China. In the present study, H.pylori infection epidemiological status and its risk factors were surveyed in Suzhou area. The prevalence rate of primary fluoroquinolone resistance to H.pylori isolates was assessed. Sixteen cases of H.pylori strains from clinical isolates and a standard strain were first calculated minimal inhibitory concentration (MIC) and mutant prevention concentration (MPC) of four fluoroquinolones. These data may lead to propose a method for H. pylori prophylaxis and how antimicrobial treatment regimens can be adjusted for H. pylori eradication.Methods:1 A questionnaire survey including 50 items related to H.pylori was conducted among 450 persons in Suzhou area,which included 234 males(52.0%)and 216 females(48.0%),aged 17-71 years old (28±l2),selected by cluster sampling in 10 rural and urban area in Suzhou . The questionnaire survey was consisted of ordinary circumastances, socio-economic status, family customs and individual habits. 14C-urea breath test (UBT) was performed to evaluate the present infection status, and peripheral blood was collected to detect H.pylori-CagA antibody to evaluate the past infection status.2 One hundred and thirty-nine strains of H. pylori isolates were obtained from gastric antral mucosal biopsy specimens. The susceptibilities of the strains to levofloxacin and moxifloxacin were determined by using Kirby-Bauer method. 3 Sixteen clinical isolates of H.pylori strains and a standard strain ATCC43504 were enriched in broth. The MICs and the MPCs of moxifloxacin,gatifloxacin,levofloxacin and ciprofloxacin against H.pylori were determined by agar plates dilution method. The results of MPC/MIC were analyzed by F test.Results:1 Four hundred and seven persons(90.4%) accomplished the questionnaire, 14C-UBT and the antibody detection in 450 participants. The positive were 196 by 14C-UBT(48.2%) and 230 by antibody detection(56.5%). The general rate of H.pylori infection was 62.9%, and it was no difference in males between females. The infection rate was difference in various age groups. Among the age groups 17-20 years was the lowest (55.4%), and 21-40 years was the highest (71.1%). H.pylori infection was related to socio-economic status. The people whose family member with peptic ulcer or gastritis seemed to be more infected with H.pylori. Other factors such as never washing tableware with detergent, neither washing hands before eating nor after using the restroom were also related with H.pylori infection. 53.8% of the respondents understand the word H.pylori.Only 38.8% of the respondents knew about how H.pylori infected.2 The resistance rates of H.pylori strains were 7.2% for levofloxacin and 5.8% for moxifloxacin in 139 patients.3 The MICs of moxifloxacin,gatifloxacin,levofloxacin, ciprofloxacin were 0.2099±0.0368, 0.2292±0.0394, 0.3958±0.0882, 0.4375±0.0567μg/ml, and the MPCs were 2.6429±0.2891, 1.1000±0.1309, 4.1677±0.5752, 1.4300±0.1370μg/ml, respectively in fluoroquinolone-susceptible strains (MIC provisionally defined as≤1.0μg/ml). The ratios of MPC to MIC were 17.3923±3.9899, 5.8624±0.8758, 13.6667±2.1532 and 3.7100±0.4188, respectively. The MPCs of moxifloxacin, gatifloxacin, levofloxacin and Ciprofloxacin for H. pylori strain ATCC29213 were 4.0, 0.5, 2.0 and 2.0 mg/L, and the ratios of MPC to MIC were 32.0, 16.0,32.0 and 8.0, respectively. These results showed that the MICs of moxifloxacin were similar to the gatifloxacin, which were smaller than that of levofloxacin and ciprofloxacin (homoscedasticity, LSD test, P<0.05). The MPC of gatifloxacin was also minimum which was near to the ciprofloxacins, and the sizes were smaller than that of levofloxacin and moxifloxacin (heterogeneity of variance, Tamhane′s T2 test, P<0.05). The ratios of MPC to MIC in levofloxacin and moxifloxacin were much bigger than that of gatifloxacin and ciprofloxacin (heterogeneity of variance, Tamhane′s T2 test, P<0.05).Conclusion:1. H.pylori infection rate is rather high in Suzhou area. H.pylori infection is related to age. It has no significant difference in gender, but has a significant correlation with Socio-economic status. H.pylori infection appears to be familial aggregation phenomenon. The bad hygienic habits of families and private individual are the risk factors for H.pylori infection.2. The resistance rates of H.pylori to fluoroquinolones are below 10% in Sozhou area.3. Gatifloxacin and ciprofloxacin exhibits excellent activity in restricting the growth of the least susceptible, single-step mutant of H. pylori strains due to their lower MPC. Combined with their pharmacokinetic parameters obtained from other literatures, moxifloxacin, gatifloxacin and levofloxacin could restrict the selective enrichment of resistant mutants among H.pylori clinical isolates. Thus, gatifloxacin appeared to be active against resistant subpopulations selectively enriched H. pylori. The alternative use of gatifloxacin may be prior to moxifloxacin, levofloxacin and ciprofloxacin for H. pylori eradication in the present study.
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