No abstract

Organic acids have been shown to be effective in reducing the presence of pathogenic bacteria on hot beef carcass surfaces; however, application for decontaminating chilled carcasses has not been fully evaluated. In this study, a postchill, 30-s lactic acid spray (500 ml of 4% L-lactic acid, 55 degrees C) was applied onto outside rounds that had been contaminated with Escherichia coli O157:H7 and Salmonella Typhimurium, subsequent to prechill hot carcass treatments consisting of water wash alone or water wash followed by a 15-s lactic acid spray (250 ml of 2% L-lactic acid, 55 degrees C). The prechill treatments reduced both pathogens by 3.3 to 3.4 log cycles (water wash alone) to 5.2 log cycles (water wash and lactic acid). In all cases, the postchill acid treatment produced an additional reduction in E. coli O157:H7 of 2.0 to 2.4 log cycles and of 1.6 to 1.9 log cycles for Salmonella Typhimurium. The counts of both pathogens remained significantly lower in ground beef produced from the outside rounds that received prechill and postchill acid spray than from those that received a postchill spray only. These data indicate that organic acid sprays may be successfully applied for pathogen reduction in beef carcass processing after the cooler, especially when combined with prechill treatments.

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Helicobacter pylori has been isolated from the human stomach with media containing only minimal selective agents. However, current research on the transmission and sources of infection requires more selective media due to the higher numbers of contaminants in environmental, oral, and fecal samples. The objective of this study was to develop and evaluate detection techniques that are sufficiently selective to isolate H. pylori from potential animal and food sources. Since H. pylori survives in the acidic environment of the stomach, low pH with added urea was studied as a potential selective combination. H. pylori grew fairly well on H. pylori Special Peptone plating medium supplemented with 10 mM urea at pH 4.5, but this pH did not sufficiently inhibit the growth of contaminants. Various antibiotic combinations were then compared, and a combination consisting of 10 mg of vancomycin per liter, 5 mg of amphotericin B per liter, 10 mg of cefsulodin per liter, 62,000 IU of polymyxin B sulfate per liter, 40 mg of trimethoprim per liter, and 20 mg of sulfamethoxazole per liter proved to be highly selective but still allowed robust colonies of H. pylori to grow. This medium was highly selective for recovering H. pylori from cattle and beef samples, and it is possible that it could be used to enhance the recovery of this bacterium from human and environmental samples, which may be contaminated with large numbers of competing microorganisms.In 1982 Warren and Marshall (17) isolated a new spiralshaped bacterium from the stomachs of humans with gastric ulcers, which was named Campylobacter pyloridis. Further research on this novel bacterium revealed significant morphological, biochemical, and genetic differences from other Campylobacter spp., and the microorganism was eventually renamed Helicobacter pylori (7). Since then, it has been determined that H. pylori is the most prevalent bacterial pathogen in the world and infects approximately one-half of the world's population (10). Infection with H. pylori causes numerous medical conditions, including gastritis, peptic ulcers, gastric carcinomas, and mucosa associated lymphoid tissue tumors (2, 9, 12).It has not been necessary for the media used to isolate H. pylori from the stomach to be highly selective because relatively few contaminants survive in the low-pH environment of the stomach (13). However, current research on the transmission and sources of infection requires more selective media. In several studies workers have tried to determine the prevalence of H. pylori in the oral cavities or feces of infected patients, but these efforts have been hindered by the large number of contaminants and the fastidious nature of the bacterium (3, 5, 16). Therefore, the need for a more selective medium has become increasingly important.The objective of this study was to develop and evaluate detection techniques that are selective enough so that H. pylori can be isolated from potential animal and food sources. Since H. pylori has the unique ability to survive in the highly acidic envi...

This study focused on important factors related to the potential of cattle and beef products to transmit Helicobacter pylori to humans. Mucosal samples were collected from the rumen and abomasum of 105 cattle and were plated on a selective medium to isolate Helicobacter spp.; none of the samples examined contained these bacteria. Studies were also conducted to determine how long H. pylori survives in refrigerated or frozen ground beef; results indicated that the microorganism dies rapidly in ground beef, whether refrigerated or frozen. Packaging in vacuum or air had little effect on survival of the organism. The number of H. pylori decreased in refrigerated samples from 3.3 log10 CFU/g on day 0 to 1.4 log10 CFU/g on day 6. H. pylori died even more rapidly when frozen, decreasing from 3.3 log10 CFU/g on day 0 to 0.5 log10 CFU/g on day 6. Retail beef cuts (n = 20) were also examined for the presence of H. pylori by direct plating on a selective medium and by incubation in an enriched broth followed by plating on a selective medium. None of the retail samples contained H. pylori. This research suggests that transmission of H. pylori from beef and beef products is not a primary factor in the high prevalence of this bacterium in humans.