Comparasion of Genotype HelicoDR with real-time PCR to identify clarithromycin resitance in Helicobacter pylori
Abstract number: P802
Agudo S., Alarcón T., Urruzuno P., Somodevilla A., López-Brea M.
Objective: Clarithromycin is one of the most important antibiotics for Helicobacter pylori treatment and it is an important factor of eradication failure. The early detection of resistance is important in the treatment of H. pylori. The aim of this study was to evaluate two commercially available kits: the MutaREAL®H. pylori Real Time PCR Kit (MutaREAL Immundiagnostik), and a assay based on DNA hybridisation technology on nitrocellulose strips, Genotype® HelicoDR (Hain, Diagnostika, Nehren, Germany) for detection of point mutations in the 23S rRNA genes responsible for H. pylori clarithromycin resistance in gastric biopsies.
Methods: 49 biopsies for H. pylori were obtained from patients with gastric symptoms, received at the Department of Microbiology from December 2007 to May 2008. Standard microbiological procedures were used for H. pylori culture. Clarithromycin resistance was determined by E-test. DNA extraction was carried out by the NucliSens easyMAG platform with the NucliSens magnetic extraction reagents (bioMérieux) according to the manufacturer instructions. MutaREAL®Helicobacter pylori Real Time PCR Kit and Genotype® HelicoDR was used to clarithromycin resistance in H. pylori following manufacturer recommendations.
Results: All biopsies showed a positive result with the MutaREAL® kit and Gentotype® HelicoDR. 24 out of 49 showed clarithromycin resitance by E-test. The Real time PCR detected clarithromycin resistance in 21 cases with a sensitivity and especificity 87.5% and 92%, respectively, compared with phenotypical methods. The Genotype® HelicoDR detected resistance in 27 cases: 20 biopsies had one point of mutation, 2 biopsies had two points of mutation and 5 biopsies showed hetero-resistance with a wild type and mutated strain. The sensitivity and specificity were 100% and 96%, respectively. The mutation A2143G was detected in all specimens, and the mutation A2142C in two biopsies with two points of mutation.
Conclusions: MutaREAL® Kit and Genotype®HelicoDR were able to detect clarithromycin susceptibility with high sensitivity and specificity and are quicker than culture. Genotype®HelicoDR had better sensitivity and specificity and it was possible to detect the type of mutation and hetero-resitance strains. Real Time PCR is suitable to be done in 1 hour after DNA extraction.
|Session name:||19th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Helsinki, Finland, 16 - 19 May 2009|
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