A new 24 h ELISA culture based method for Helicobacter pylori chemosusceptibility

Background Clarithromycin (CH) and metronidazole (MZ) are routinely used in Helicobacter pylori treatment regimes. Recently, treatment with these antibiotics has been reported to fail in >30% of patients due to increasing resistance. The common chemosusceptibility methods are cumbersome and take up to 14 days. Chemosusceptibility of H pylori is therefore rarely checked. Aim To develop a rapid susceptibility test (RST) for H pylori. Methods Preliminary experiments were performed to find a broth medium able to support the growth of H pylori in 20 h and a reliable detection method to quickly detect the amount of H pylori grown in the media. A mixture of different components was the best broth medium; ELISA was chosen as the detection technique. Performance of the new RST was compared to a gold standard (break point agar dilution method). 200 consecutive patients were tested for H pylori infection and chemosusceptibility to CH and MZ by the gold standard and RST. Results 111 patients were infected with H pylori. 105 of these were positive by both RST and the gold standard culture method; 75/105 and 68/105 strains were susceptible to CH and MZ, respectively. RST misdiagnosed 2 strains of CH and 10 strains of MZ. Conclusions A new simple and rapid chemosusceptibility test for H pylori has been validated, which is simple to perform and reduces the procedure time from 6–14 days to 24 h