Abstract
Cases of human gastric cancer due to Helicobacter pylori have been reported worldwide and animals might act as a reservoir of infection in certain circumstances. The recent few decades showed a rapid decline in the incidence of gastric cancer, which was mainly due to the decrease in H. pylori infection. The aims of the present study were to determine the prevalence of H. pylori among livestock and investigate whether the animal isolates can be transmitted through contaminated milk causing gastric infection. Feces and milk samples were collected from apparently healthy cows, buffaloes, and sheep, and were examined by nested PCR and genotyping. The PCR positive samples were further subjected to bacterial culture followed by partial 16s sequencing of the isolates. Twenty-nine percent of the animals showed the presence of H. pylori, mainly the virulent cagA+vacA+s1a m1 i1 genotype, which is known to be associated with serious diseases in humans. The spiral viable culturable form (SVCF) of this strain was inoculated into UHT (ultra-high temperature) milk and remained viable for up to 10 days at 4 °C. Increasing period of storage and or temperature led to a decrease in the number of the SVCF and occurrence of the coccoid viable non-culturable form (CVNCF). The infectivity of the survived forms was determined by feeding healthy groups of laboratory mice with the contaminated UHT milk containing SVCF or CVNCF for 40 days. The gastric mucosa of the two mice groups showed similar levels of H. pylori load. This highlights that H. pylori can persist in contaminated milk by entering a non-culturable state, which can induce gastric infection.
Highlights
Helicobacter pylori is the most important etiological agent of chronic gastritis and peptic ulcer[1,2]
The aims of the present study were to examine the occurrence of H. pylori among healthy livestock in Egypt, characterize the bacterial virulence genotypes, to investigate the length of survival of the animal isolates in contaminated ultra-high temperature (UHT) milk as well as their ability to be transmitted through milk via the oral route and causing gastric infection in healthy laboratory mice groups
Other studies reported that people that have direct contact with farm animals such as abattoir workers[30] and shepherds[31,32] have a high prevalence of H. pylori infection, suggesting a role of animals in the transmission cycle
Summary
Helicobacter pylori is the most important etiological agent of chronic gastritis and peptic ulcer[1,2]. This variation is linked to specific clinical outcomes, for example, H. pylori strains that carry s1-m1 or -m2 are more virulent than those with s2 alleles, whereas the i-region is thought to determine the carcinogenic ability of the strains[19] Another important virulence factor is the cytotoxin-associated gene product (cagA) which is encoded on the cag pathogenicity island (PAI). The aims of the present study were to examine the occurrence of H. pylori among healthy livestock in Egypt, characterize the bacterial virulence genotypes, to investigate the length of survival of the animal isolates in contaminated UHT milk as well as their ability to be transmitted through milk via the oral route and causing gastric infection in healthy laboratory mice groups
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