Punctual mutations in 23S rRNA gene of clarithromycinresistant Helicobacter pylori in Colombian populations

AIM To characterize punctual mutations in 23S rRNA gene of clarithromycin-resistant Helicobacter pylori(H. pylori) and determine their association with therapeutic failure.METHODS PCR products of 23S rRNA gene V domain of 74 H. pylori isolates; 34 resistant to clarithromycin(29 from a low-risk gastric cancer(GC) population: TumacoColombia, and 5 from a high-risk population: TuquerresColombia) and 40 from a susceptible population(28 from Tumaco and 12 from Túquerres) were sequenced using capillary electrophoresis. The concordance between mutations of V domain 23S rRNA gene of H. pylori and therapeutic failure was determined using the Kappa coefficient and Mc Nemar's test was performed to determine the relationship between H. pylori mutationsand clarithromycin resistance.RESULTS23S rRNA gene from H. pylori was amplified in 56/74 isolates, of which 25 were resistant to clarithromycin(20 from Tumaco and 5 from Túquerres, respectively). In 17 resistant isolates(13 from Tumaco and 4 from Túquerres) the following mutations were found: A1593 T1, A1653 G2, C1770 T, C1954 T1, and G1827 C in isolates from Tumaco, and A2144 G from Túquerres. The mutations T2183 C, A2144 G and C2196 T in H. pylori isolates resistant to clarithromycin from Colombia are reported for the first time. No association between the H. pylori mutations and in vitro clarithromycin resistance was found. However, therapeutic failure of eradication treatment was associated with mutations of 23S rRNA gene in clarithromycin-resistant H. pylori(κ = 0.71).CONCLUSION The therapeutic failure of eradication treatment in the two populations from Colombia was associated with mutations of the 23S rRNA gene in clarithromycinresistant H. pylori.

Genomic variability of Helicobacter pylori isolates of gastric regions from two Colombian populations

AIM To compare the genomic variability and the multiple colonization of Helicobacter pylori(H. pylori) in patients with chronic gastritis from two Colombian populations with contrast in the risk of developing gastric cancer(GC): Túquerres-Nari?o(High risk) and Tumaco-Nari?o(Low risk).METHODS Four hundred and nine patients from both genders with dyspeptic symptoms were studied. Seventy-two patients were included in whom H. pylori was isolated from three anatomic regions of the gastric mucosa,(31/206) of the high risk population of GC(Túquerres) and(41/203) of the low risk population of GC(Tumaco). The isolates were genotyped by PCR-RAPD. Genetic diversity between the isolates was evaluated by conglomerates analysis and multiple correspondence analyses. RESULTS The proportion of virulent genotypes of H. pylori was 99% in Túquerres and 94% in Tumaco. The coefficient of similarity of Nei-Li showed greater genetic diversityamong isolates of Túquerres(0.13) than those of Tumaco(0.07). After adjusting by age, gender and type of gastritis, the multiple colonization was 1.7 times more frequent in Túquerres than in Tumaco(P = 0.05).CONCLUSION In Túquerres, high risk of GC there was a greater probability of multiple colonization by H. pylori. From the analysis of the results of the PCR-RAPD, it was found higher genetic variability in the isolates of H. pylori in the population of high risk for the development of GC.