Rapid identification of and assessment of clarithromycin susceptibility from clinical specimens using FISH.

remains one of the most common bacterial infections worldwide. Clarithromycin resistance is the most important cause of eradication failures. Effective antibiotic therapies in infection must be rapidly adapted to local resistance patterns. We investigated the prevalence of clarithromycin resistance due to mutations in positions 2142 and 2143 of 23SrRNA gene of by fluorescence hybridisation (FISH), and compared with culture and antimicrobial susceptibility testing in 234 adult patients with dyspepsia who were enrolled. Antrum and corpus biopsy specimens were obtained for rapid urease test, histopathology and culture. Epsilometer test was used to assess clarithromycin susceptibility. presence and clarithromycin susceptibility were determined by FISH in paraffin-embedded biopsy specimens. We found that 164 (70.1%) patients were positive for based on clinical criteria, 114 (69.5% CI 62.5-76.6%) were culture positive, and 137 (83.5% CI 77.8-89.2%) were FISH positive. Thus the sensitivity of FISH was significantly superior to that of culture. However specificity was not significantly different (91.4 versus 100.0%, respectively). The resistance rate to clarithromycin for both antrum and corpus was detected in -positive patients; 20.2% by FISH and 28.0% by E-test.The concordance between E-test and FISH was only 89.5% due to the presence of point mutations different from A2143G, A2142G or A2142C. We conclude that FISH is significantly more sensitive than culture and the E-test for the detection of and for rapid determinination of claritromycin susceptibility. The superior hybridisation efficiency of FISH is becoming an emerging molecular tool as a reliable, rapid and sensitive method for the detection and visualisation of , especially when the management of eradication therapy is necessary. This is particularly important for the treatment of patients with eradication failure.