Abiodun T Seriki1, Stella I Smith2, Adeyemi I Adeleye1, Muinah A Fowora3. 1. Department of Microbiology, University of Lagos, Akoka, Lagos, Nigeria. 2. Molecular Biology & Biotechnology Department, Nigerian Institute of Medical Research (NIMR), Yaba, Lagos, Nigeria. Electronic address: stellasmith@nimr.gov.ng. 3. Molecular Biology & Biotechnology Department, Nigerian Institute of Medical Research (NIMR), Yaba, Lagos, Nigeria.
Abstract
OBJECTIVES: The aim of this study was to determine the occurrence of 16S rRNA mutations associated with low-level tetracycline resistance in Helicobacter pylori isolates from adult dyspeptic patients in South West Nigeria. METHODS: Susceptibility testing to tetracycline of 50 H. pylori isolates was performed by Etest. The 535-bp conserved region of the H. pylori tetracycline-binding site of 16S rRNA was amplified by PCR, followed by sequencing and multiple sequence alignment for all 50 clinical isolates. RESULTS: Of the 50 clinical isolates examined, DNA sequence analysis revealed nucleotide substitutions in 7 isolates at positions 926-928. Of the seven isolates, two demonstrated reduced susceptibility to tetracycline with Etest minimum inhibitory concentrations (MICs) of 0.75-1.0mg/L, whilst the other five isolates were resistant with MICs of 1.5-24mg/L (resistance breakpoint >1mg/L). The two isolates with reduced susceptibility had single nucleotide substitution of A926G, whilst the five resistant isolates demonstrated double base pair substitutions of G927T/A928C and A926G/A928C and a single nucleotide substitution of A926G. CONCLUSIONS: This study shows that low-level tetracycline resistance amongst H. pylori-positive dyspeptic patients is associated with reduced susceptibility and resistance to tetracycline. This is the result of 1-bp and 2-bp differences in positions 926 and 926-928, respectively, in the 16S rRNA of H. pylori.
OBJECTIVES: The aim of this study was to determine the occurrence of 16S rRNA mutations associated with low-level tetracycline resistance in Helicobacter pylori isolates from adult dyspepticpatients in South West Nigeria. METHODS: Susceptibility testing to tetracycline of 50 H. pylori isolates was performed by Etest. The 535-bp conserved region of the H. pyloritetracycline-binding site of 16S rRNA was amplified by PCR, followed by sequencing and multiple sequence alignment for all 50 clinical isolates. RESULTS: Of the 50 clinical isolates examined, DNA sequence analysis revealed nucleotide substitutions in 7 isolates at positions 926-928. Of the seven isolates, two demonstrated reduced susceptibility to tetracycline with Etest minimum inhibitory concentrations (MICs) of 0.75-1.0mg/L, whilst the other five isolates were resistant with MICs of 1.5-24mg/L (resistance breakpoint >1mg/L). The two isolates with reduced susceptibility had single nucleotide substitution of A926G, whilst the five resistant isolates demonstrated double base pair substitutions of G927T/A928C and A926G/A928C and a single nucleotide substitution of A926G. CONCLUSIONS: This study shows that low-level tetracycline resistance amongst H. pylori-positive dyspeptic patients is associated with reduced susceptibility and resistance to tetracycline. This is the result of 1-bp and 2-bp differences in positions 926 and 926-928, respectively, in the 16S rRNA of H. pylori.