Genetic determinants of Helicobacter pylori resistance to metronidazole in Uganda

Abstract

Background. About half of the world's population is affected with H. pylori infections, which typically start in childhood and can progress to chronic infections. It causes a number of illnesses, the most common being peptic ulcer disease and gastritis. Proton pump inhibitors and a combination of antimicrobial medicines are recommended for the eradication of H. pylori. These antimicrobial agents include; clarithromycin (CLA), metronidazole, and amoxicillin as first line, while others such as fluoroquinolones (FLQ) and tetracycline are used in second-line regimens. Resistance to metronidazole by Helicobacter pylori has caused its elimination using metronidazole containing regimens ineffective. Although it is believed that mutations in the rdxA and frxA genes cause H. pylori resistance to metronidazole, little is known about the genetic factors that contribute to this resistance in patients from Uganda. Objectives; To determine the frequency of rdxA gene mutations of H. pylori isolates from Ugandan patients. To determine rdxA mutations of H. pylori isolates that correlate with the resistant phenotype. Methods; DNA was be extracted from both resistant and susceptible isolates. The rdxA genes were amplified using conventional PCR, and their sequences determined using Sanger sequencing. The sequences were then analyzed for sequence identity and similarity using bioinformatics tools at NCBI. Sequence comparison with reference rdxA gene of sequence KC491784.1 Helicobacter pylori strain IR9 isolate HP9 was the performed in Bio edit software 7.2. Results; Sequences obtained were dissimilar to those of the reference sequence which indicated that the primer sets used did not amplify the target rdxA gene either due mutation at the sites where primer had to anneal or the primer sets were not specific for the target gene.