The survival and growth of Helicobacter pylori under enrichment conditions in fresh, autoclaved and irradiated ground beef were determined. H. pylori grew in autoclaved ground beef at 37°C under microaerobic conditions in brain heart infusion broth with 7% horse serum at pH 7.3 after 3 to 7 days of lag time but did not grow within 7 days in irradiated (10 kGy) ground beef under the same enrichment conditions. Adjustment of the enrichment broth to pH 5.5 enabled the growth (ca. 2 log10 CFU/ml) of H. pylori within 7 days in the presence of irradiated ground beef and the prolific growth (ca. 3 to 4 log10 CFU/ml) of H. pylori within 3 days in the presence of autoclaved beef. H. pylori in fresh ground beef could not be isolated from enrichment media with antibiotics; however, H. pylori ureA could be detected by polymerase chain reaction (PCR) in such enrichment media after 1 to 3 days of incubation at 37°C. The addition of supplements, i.e., 0.3% mucin, 0.05% ferrous sulfate, and 0.05% sodium pyruvate or 0.008 M urea, or the adjustment of the enrichment broth pH to 5.5 or 4.5 enabled the detection of H. pylori ureA in enrichment media incubated for 1, 2, 3, and/or 7 days at 37°C. H. pylori in sterile milk refrigerated at 4°C at an initial level of 106 CFU/ml was inactivated to an undetectable level within 6 days; however, H. pylori was not detected either by a PCR assay or by the plating of enrichment cultures of 120 raw bovine milk samples.

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Author notes

Present address: Department of Food Science and Human Nutrition, Clemson University, 217 Poole Agricultural Center, Clemson, SC 29634-0371, USA.