title: Evaluation of a new test, genotype HelicoDR, for molecular detection of antibiotic resistance in Helicobacter pylori.
abstract: The eradication rate of Helicobacter pylori by standard therapy is decreasing due to antibiotic resistance, mainly to clarithromycin. Our aim was to provide a new molecular test to guide the treatment of new and relapsed cases. We first studied 126 H. pylori strains for phenotypic (MIC) and genotypic resistance to clarithromycin (rrl mutation) and levofloxacin (gyrA mutation) and then developed a DNA strip genotyping test on the basis of the correlation results and literature data. Clinical strains (n = 92) and gastric biopsy specimens containing H. pylori (n = 105) were tested blindly with the new molecular test GenoType HelicoDR. The presence of mutations or the absence of hybridization with wild-type sequences was predictive, in rrl for clarithromycin resistance in 91 cases (mostly the A2147G mutation) and in gyrA for levofloxacin resistance in 58 cases (mutations at codon 87 or 91). Genotyping revealed a mix of genotypes in 33% of the cases, reflecting a coinfection or selection for resistant mutants. The sensitivity and specificity of detecting resistance were 94% and 99% for clarithromycin and 87% and 98.5% for levofloxacin, respectively. The concordance scores were 0.96 for clarithromycin and 0.94 for levofloxacin. With global resistance rates of 46% for clarithromycin and 25% for levofloxacin, which were observed for consecutive positive biopsy specimens from 2007 and 2008, the positive and negative predictive values for detecting resistance were 99% and 94% for clarithromycin and 96% and 96% for fluoroquinolone. GenoType HelicoDR is efficient at detecting mutations predictive of antibiotic resistance in H. pylori when applied to strains or directly to gastric biopsy specimens.
authors.affiliation: Laboratoire de Bactériologie-Virologie-Hygiène, Hôpital Saint Louis, 1 Avenue Claude Vellefaux, 75018 Paris Cedex, France. emmanuelle.cambau@sls.aphp.fr
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cambau
authors.forename: Vera
authors.initials: V
authors.lastname: Allerheiligen
authors.forename: Céline
authors.initials: C
authors.lastname: Coulon
authors.forename: Céline
authors.initials: C
authors.lastname: Corbel
authors.forename: Christine
authors.initials: C
authors.lastname: Lascols
authors.forename: Lionel
authors.initials: L
authors.lastname: Deforges
authors.forename: Claude-James
authors.initials: CJ
authors.lastname: Soussy
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Delchier
authors.forename: Francis
authors.initials: F
authors.lastname: Megraud
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D017291:Clarithromycin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D005838:Genotype; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D064704:Levofloxacin; D008826:Microbial Sensitivity Tests / Q000379:methods*; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009693:Nucleic Acid Hybridization / Q000379:methods; D015242:Ofloxacin / Q000494:pharmacology*; D017354:Point Mutation; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D017384:Sequence Deletion
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D064704:Levofloxacin; D015242:Ofloxacin; D027081:DNA Gyrase; D017291:Clarithromycin