Jiang Xiuping, Doyle Michael P
Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.
J Food Prot. 2002 Dec;65(12):1949-54. doi: 10.4315/0362-028x-65.12.1949.
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.
测定了幽门螺杆菌在新鲜、高压灭菌和辐照绞碎牛肉的富集条件下的存活和生长情况。幽门螺杆菌在含7%马血清、pH 7.3的脑心浸液肉汤中，于37℃微需氧条件下，在高压灭菌的绞碎牛肉中经过3至7天的延迟期后生长，但在相同富集条件下，在辐照（10千戈瑞）的绞碎牛肉中7天内未生长。将富集肉汤的pH值调至5.5可使幽门螺杆菌在辐照绞碎牛肉存在的情况下7天内生长（约2 log10 CFU/ml），在高压灭菌牛肉存在的情况下3天内大量生长（约3至4 log10 CFU/ml）。新鲜绞碎牛肉中的幽门螺杆菌无法从含抗生素的富集培养基中分离出来；然而，在37℃孵育1至3天后，通过聚合酶链反应（PCR）可在这种富集培养基中检测到幽门螺杆菌ureA。添加补充剂，即0.3%粘蛋白、0.05%硫酸亚铁、0.05%丙酮酸钠或0.008 M尿素，或将富集肉汤的pH值调至5.5或4.5，可在37℃孵育1、2、3和/或7天的富集培养基中检测到幽门螺杆菌ureA。初始水平为10(6) CFU/ml、在4℃冷藏的无菌牛奶中的幽门螺杆菌在6天内失活至不可检测水平；然而，对120份生牛乳样品的富集培养物进行PCR检测或平板培养均未检测到幽门螺杆菌。
