Detecção molecular e genotipagem de Helicobacter Pylori em pacientes dispépticos atendidos no Hospital Central de Maputo

Abstract

Background: Helicobacter pylori (H. pylori) is a human pathogenic bacterium responsible for a variety of gastric diseases, including dyspepsia. The global prevalence of its infection is approximately 50%, but can reach 90% in developing countries, such as those in sub-Saharan Africa, where Mozambique is included. H. pylori strains show a high level of genotypic diversity and express several genes that contribute to their pathogenicity and resistance. In Mozambique, there is lack of information on H. pylori infection, its resistance to antibiotics, its virulence factors, and its phylogeny. Therefore, we aimed to investigate the occurrence of H. pylori infection and its genomic characterization in dyspeptic patients seen at the Department of Gastroenterology, Hospital Central de Maputo, in Mozambique. Methodology: This is a cross-sectional descriptive study conducted between June 2017 and June 2020, in which 171 dyspeptic patients were recruited, and through Upper GI endoscopy, gastric biopsies were collected from those patients. To perform molecular analysis, bacterial genomic DNA was directly extracted from gastric biopsies, and PCR was performed for the detection of H. pylori and its resistance mechanisms to clarithromycin (23S rRNA), fluoroquinolones (gyrA) and metronidazole (rdxA) and, mutations conferring resistance to these antibiotics were investigated by sequencing these genes (23S rRNA, gyrA and rdxA). Additionally, virulence genes (vacA, dupA and cagA) were detected, and MLST typing was also performed for the phylogenetic characterization of H. pylori strains infecting patients Results: Of the 171 samples tested, H. pylori was detected in 56.1% (96/171). The clarithromycin resistance rate was 10.4% (the responsible mutations were: A2141G and A2142G), the fluoroquinolones resistance rate was 20% (the responsible mutations were: N87I and D91G) and, the metronidazole resistance rate was 55.2% (4 types of mutations responsible for metronidazole resistance were identified which include, D59N, R90K, H97T and A118T. However, in many cases, they appeared in combination, with D59N+R90K+A118T being the most frequent combination). Regarding virulence genes, vacA was detected in all samples (100%), dupA in 61.5% and cagA was detected only in 16.7% of samples and, among the combinations of vacA genotype, vacA s1/m2 was the most frequent. Characterization of phosphorylation sites in cagA- positive samples revealed that 93.8% were EPIYA-ABC and only 6.2% were EPIYA-ABCCC. Based on MLST typing, a diversity was found among H. pylori strains infecting patients and, they were classified as hpAfrica2 (50%), hpAfrica1 (33.3%) and hpEurope (16.7%). Conclusion: More than half of the dyspeptic patients seen at the Department of Gastroenterology, Hospital Central de Maputo, are infected with H. pylori strains resistant to metronidazole and fluoroquinolones. However, their virulence factors suggest moderate virulence of these strains