Prevalence and Genotyping of Helicobacter pylori strains isolated from raw milk samples

Despite the high importance of Helicobacter pylori, the main source of the bacterium and the habits of its transmission to human populations have not been determined yet. The present study was performed to evaluate the prevalence and genotyping of Helicobacter pylori strains isolated from raw milk samples. A total of 180 raw bovine, ovine and caprine milk samples were randomly collected from Fars province. The presence of Helicobacter pylori in raw milk samples were was studied using the microbial culture. Genomic DNA was extracted from Helicobacter pylori isolates and the frequency of VacA, CagA, IceA and OipA genotypes was evaluated using polymerase chain reaction. In total, 53 out of 180 (29.44%) raw milk samples were contaminated with Helicobacter pylori. The prevalence of contamination in raw milk samples of bovine, ovine and caprine was 20, 38.33 and 30%, respectively. VacA s1a (69.71%), m1a (67.92%), s2 (62.26%) and m2 (58.49%) and cagA (50.94%) were the most abundant detected genotypes. The rarest detected genotypes were VacA s1c (7.54%), s1b (16.98%), m1b (18.86%) and iceA2 (7.54%), respectively. S1am1a (39.62%), s2m1a (32.07%), s1am2 (28.30%) and s2m2 (26.41%) were the most commonly detected combined genotypes. Raw milk, especially raw sheep milk, was considered as a carrier for transmission of virulent strains of Helicobacter pylori. The similarity in the genotyping pattern of the isolates probably indicates the similarity in the source of infection of the samples with Helicobacter pylori.