title: Optimizing enrichment culture conditions for detecting Helicobacter pylori in foods.
abstract: 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 degrees 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 degrees 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 degrees C. H. pylori in sterile milk refrigerated at 4 degrees C at an initial level of 10(6) 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.
authors.affiliation: Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Jiang
authors.forename: Michael P
authors.initials: MP
authors.lastname: Doyle
mesh_terms: D000818:Animals; D002417:Cattle; D003470:Culture Media; D005514:Food Irradiation; D005516:Food Microbiology; D016480:Helicobacter pylori / Q000254:growth & development* / Q000302:isolation & purification*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008461:Meat Products / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D003470:Culture Media