Helicobacter pylori:in vitro induction of resistance to antibiotics and surveillance of its resistant prevalence / 中华消化杂志

ABSTRACT

Objective Antibiotic resistance has increasingly been recognized as the major cause of treatment failure for Helicobacter pylori infection. The study was designed to compare the propensity of Helicobacter pylori to develop in vitro resistance to five commonly used antibiotics and to investigate the rates of resistance to these five antibiotics. Methods The serial passage tests were done in 7 sensitive Helicobacter pylori strains (2 type strains and 5 clinical isolates) to induce the resistance to amoxycillin, tetracycline, furazolidone, metronidazole or clarithromycin in vitro. The agar dilution tests detecting the minimal inhibitory concentration (MIC) were performed in 165 strains of Helicobacter pylori isolated from 2000 to 2001 to determine the resistance rates to the 5 antibiotics mentioned above. Results Serial passage tests showed that 5 of 7 strains of Helicobacter pylori were induced to be resistant to metronidazole and tetracycline; the inducible multiple of metronidazole was the highest. No strain was induced to be resistant to clarithromycin, but the inducible multiple of one strain was relatively high. No strain was induced to be resistant to amoxycillin or furazolidone, and the inducible multiple of furazolidone was the lowest. The resistance rates of Helicobacter pylori to metronidazole, clarithromycin, amoxycillin, tetracycline and furazolidone were 49.7% (82/165), 7.3%(12/165), 1.2% (2/165), 2.4%(4/165) and 1.2%(2/165), respectively. Conclusions Our study indicate that it is quite easy to induce the resistance to metronidazole,not difficult to clarithromycin, and relatively difficult to furazolidone or amoxycillin. The relative degree of difficulty in inducing the resistance to the drugs other than tetracycline is associated with the resistance rates detected, the fact that may help predict the changing trend of resistance rates in general population.