Impact of Helicobacter pylori transformation from bacillary to coccoid form on ureC gene detectability by conventional PCR: A comparative study and in silico analysis.

Helicobacter pylori is a bacterium that infects the stomach lining in half of the world's population and is responsible for 1 to 3% of stomach cancer cases. Colonization occurs through various morphologies, including the spiral bacillary and the coccoid form. The latter is often associated with environmental stress and poses significant challenges for molecular diagnosis, although it has been metabolically active. These coccoid forms contribute to increased antibiotic resistance, compromising the effectiveness of treatments and promoting persistent recurrent infections. The objective of our study is to compare the detectability of the ureC gene by conventional PCR in bacillary and coccoid forms isolated from gastric biopsy cultures on Helicobacter pylori Selective Agar. Our results confirmed the presence of the ureC gene in all bacillary forms (100%), whereas no amplification of this gene was observed in coccoid forms (0%). These results were corroborated by an in silico analysis of the complete genomes of coccoid forms, confirming the presence of the ureC gene with substitutions at the hybridization sites of the reverse primers. This study suggests that the failure to detect the ureC gene in coccoid forms may be associated with nucleotide variations in the regions targeted by standard primers, potentially affecting the efficiency of PCR amplification. These results highlight the need to evaluate more stable diagnostic targets for the detection of persistent forms of H. pylori and suggest that the transformation from the bacillary form to the coccoid form may be accompanied by genetic variability in certain regions of the ureC gene.