Helicobacter pylori infection in children: Utility of culture in diagnosis and study of resistance to metronidazole, clarithromycin and amoxicillin

Abstract

Resistance to antibiotics frequently used to treat Helicobacter pylori infection is one of the most important factors in treatment failure. The aims of this study were to determine the accuracy of culture and other invasive and non-invasive tests for diagnosis of H. pylori infection in children, using histological examination as the gold standard, and to evaluate rates of resistance to metronidazole, clarithromycin and amoxicillin. Between March 2003 and December 2004, gastric biopsies from 215 children were tested by histological examination, a rapid urease test and culture. In addition, stool samples were obtained from all children for H. pylori antigen testing. Sixty-four (30%) patients were positive for H. pylori by histological examination. The H. pylori fecal antigen test revealed a sensitivity of 57.8%, a specificity of 93.4%, a positive predictive value of 78.7% and a negative predictive value of 83.9%; rapid urease test had a sensitivity of 70.3%, a specificity of 94.7%, and positive and negative predictive values of 83.3% and 88.2%; culture had a sensitivity of 90.6%, a specificity of 100%, and positive and negative predictive values of 100% and 96.2%. All positive cultures were tested for susceptibility to amoxicillin, metronidazole and clarithromycin by the E-test method. Resistance rates to clarithromycin and metronidazole were 20.7% and 27.6% respectively; no resistance to amoxicillin was observed. This study confirms the place of histological examination as the definitive test for H. pylori , and shows the importance of H. pylori culture in allowing evaluation of antibiotic resistance profiles in pediatric patients.