Identification of Helicobacter suis in Pig-producing Regions of the United States22 October 2013
More than half of the pigs tested in five states showed signs of colonisation with Helicobacter suis bacteria in their stomachs, a pathogen that has been linked with gastric ulcers and similar lesions.
In a paper in Journal of Swine Health and Production, Dennis L. Foss and colleagues at Zoetis in the US describe their work to develop a non-culture-based method to determine levels of Helicobacter suis infection in porcine stomachs and to test the method in a sample of pigs from a variety of regions in the United States.
In their introduction, they explain that gastric, Helicobacter-like bacteria have been reported in pigs from various countries for over 20 years. H. suis is a spiral bacterium found in the stomachs of swine; it is a distinct species of Helicobacter, identical to H. heilmannii type 1 found in humans and is not closely related to H. pylori or the H. pylori-like organisms previously reported in experimental swine.
Previous studies show the prevalence of H. suis appears to be very low prior to weaning, but increases rapidly following weaning and is very high in adult pigs (more than 90 per cent) and at slaughter (77 per cent).
The specific causal relationship of H. suis with gastric ulcers and related lesions remains unclear, according to Foss and co-authors. However, there has been a long-standing correlation of Helicobacter-like bacteria with gastric lesions in pigs. Several studies have shown that pigs with more severe ulcers tended to have higher numbers of helicobacters or a greater likelihood of being colonised by helicobacters.
Since gastric ulcers have a complex aetiology, they continue, it is not surprising that attempts to experimentally induce gastric ulcers with H. suis have generally been inconclusive. However, two recent experimental infection studies have shown H. suis infection can reduce daily weight gain by five to 10 per cent. Furthermore, H. suis-infected pigs were more likely to have ulcerative lesions of the stomach and microscopic signs of gastritis than were non-infected pigs.
To date, Foss and co-authors report that no comprehensive information on the presence of H. suis in US pigs has been available so in this paper, the Kalamazoo, Michigan-based group developed a polymerase chain reaction (PCR) assay to quantify total Helicobacter generic DNA and H. suis species-specific DNA in pig stomachs.
Primers were derived from 16s ribosomal RNA (rRNA) gene sequences, selected on the basis of relative conservation and divergence of sequences across the various Helicobacter species. The assay was standardised using cloned 16s rRNA sequences and was initially tested with DNA isolated from cultured H. suis.
Gastric mucosal scrapings were collected from pigs in three geographic regions of the United States, including the North (Minnesota and Michigan), East Central (Iowa), and South (Oklahoma and North Carolina).
Of a total of 118 pigs tested, approximately half (55.1 per cent; 95 per cent CI: 46.1 to 63.8 per cent) were positive for H. suis DNA. H. suis DNA was detected in pigs from all states tested.
Foss and colleagues concluded that H. suis is present in US pigs and may be relevant to pig health and production. This quantitative PCR assay will facilitate further study of H. suis in pigs, including potential therapeutic and prophylactic interventions.
Foss D.L., L.A. Kopta, J.A. Paquette, T.L. Bowersock, L.J. Choromanski, J.E. Galvin, T.K. Godbee, R.W. Laurinat and M. Sanchez. 2013. Identification of Helicobacter suis in pig-producing regions of the United States. J Swine Health Prod. 21(5):242–247.
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