Ann Hellemans

Prevalence of ‘Candidatus Helicobacter suis’ in pigs of different ages

Samples from the antrum and fundus of the stomachs of 457 pigs from 22 different herds were screened for the presence of ‘Candidatus Helicobacter suis’ by pcr, and samples from the antrum and/or fundus of 222 of the stomachs were tested for urease activity. The prevalence of the infection was very low before weaning, increased rapidly after weaning and reached 90 per cent in the adult boars and sows. The agreement between the results obtained with the pcr test and the urease test was very good for some age groups and sampling sites, but poor for other age groups and sampling sites.

Experimental Infection of Pigs with ‘ Candidatus Helicobacter suis’

Abstract‘Candidatus Helicobacter suis’ is a spiral-shaped bacterium that colonizes the stomach of more than 60% of slaughter pigs. The role of ‘Candidatus Helicobacter suis’ in gastric disease of pigs is still unclear. Experimental studies in pigs are lacking because this bacterium is unculturable until now. An inoculation protocol using ‘Candidatus Helicobacter suis’ infected mouse stomach homogenate was used to reproduce the infection in pigs. Control animals were inoculated using negative mouse stomach homogenate. Pigs were inoculated three times with one-week intervals and euthanized 6 weeks post inoculation. Tissue samples were taken from different mucosal stomach regions to detect ‘Candidatus Helicobacter suis’ by PCR and urease test. Mucosal inflammation was evaluated on formalin-fixed tissue samples. Lesions in the pars oesophagea were scored macroscopically. Infection was succesful in all challenged animals, with the antrum and the fundus being predominantly positive. Infection was associated with infiltration of lymphocytes and plasma cells in the antral mucosa, evolving to follicular gastritis. No apparent inflammation of the fundic stomach region was detected in the infected animals. A clear link between ‘Candidatus Helicobacter suis’ and pars oesophageal lesions could not be found.

Evaluation of Antibiotic Treatment against “Candidatus Helicobacter suis” in a Mouse Model

ABSTRACT “Helicobacter heilmannii” (proposed name) type 1 colonizes the human stomach. It has been shown to be identical to“ Candidatus Helicobacter suis,” a Helicobacter species colonizing the stomachs of >60% of slaughter pigs. This bacterium has not been isolated in vitro until now. Antibiotic susceptibility testing of “Candidatus Helicobacter suis” has not been carried out so far. For the present study, a mouse model was adopted to evaluate the antibiotic susceptibility of this organism. Mice infected with“ Candidatus Helicobacter suis” were treated with amoxicillin and omeprazole, a therapy which is used to treat H. heilmannii infections in humans. Two different isolates of“ Candidatus Helicobacter suis” were tested. The excretion of bacterial DNA was assessed during treatment, using PCR on fecal samples. At the end of the experiment, 8 days after the cessation of treatment, the presence of infection was evaluated using a urease test and a PCR test on stomach samples. A marked decrease in the excretion of bacterial DNA was observed a few days after the onset of treatment, and the level remained low until the end of the experiment. A difference in susceptibility between the two“ Candidatus Helicobacter suis” isolates was pointed out. The in vivo mouse model infected with“ Candidatus Helicobacter suis” will be useful for further screening of potential therapeutic regimens.

Protective immunization with homologous and heterologous antigens against Helicobacter suis challenge in a mouse model.

Helicobacter (H.) suis colonizes the stomach of more than 60% of slaughter pigs and is also of zoonotic importance. Recently, this bacterium was isolated in vitro, enabling the use of pure cultures for research purposes. In this study, mice were immunized intranasally or subcutaneously with whole bacterial cell lysate of H. suis or the closely related species H. bizzozeronii and H. cynogastricus, and subsequently challenged with H. suis. Control groups consisted of non-immunized and non-challenged mice (negative control group), as well as of sham-immunized mice that were inoculated with H. suis (positive control group). Urease tests on stomach tissue samples at 7 weeks after challenge infection were negative in all negative control mice, all intranasally immunized mice except one, and in all and 3 out of 5 animals of the H. cynogastricus and H. suis subcutaneously immunized groups, respectively. H. suis DNA was detected by PCR in the stomach of all positive control animals and all subcutaneously immunized/challenged animals. All negative control animals and some intranasally immunized/challenged mice were PCR-negative. In conclusion, immunization using antigens derived from the same or closely related bacterial species suppressed gastric colonization with H. suis, but complete protection was only achieved in a minority of animals following intranasal immunization.

MIRRI Clusters of Expertise

A. Zuzuarregui1, R. Aznar1, D. R. Arahal1, C. Bizet2, P. De Vos3, A. Hellemans3, F. Van Hauwenhuyse3, D. Martin4, M. Schungel4, E. Stackebrand4, D. Smith5, C. Varese6 1Coleccion Espanola de Cultivos Tipo (CECT) and Microbiology and Ecology Department, Valencia University, Paterna (Valencia), Spain, 2Biological Resource Center of Institut Pasteur, Institut Pasteur, Paris, France, 3Laboratory of Microbiology UGent (LMG), Ghent University, Ghent, Belgium, 4Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ), Leibniz Institute, Braunschweig, Germany, 5CABI Bakeham Lane, CAB International, Egham Surrey, United Kingdom, 6Mycotheca Universitatis Taurinensis (MUT), Turin University, Turin, Italy