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The consumption of foodborne pathogens contaminated in food is one of the major causes of diarrheal diseases in Thailand. The objective of this study was to evaluate the prevalence and types of contaminating bacteria in retailed foodstuffs in Thailand. Food from four categories (137 samples total), including meat (51 samples), vegetables (38 samples), fish or seafood (37 samples), and fermented food (11 samples), was purchased randomly from seven different open-markets and seven supermarkets in Thailand from August 2010 to March 2011. Seven types of major foodborne pathogens were identified using conventional culture methods. Approximately 80% of meat samples tested was contaminated with Salmonella spp. In contrast, the Salmonella spp. contamination rate of vegetable (5%) or fermented food (9%) samples was comparatively low. Six strains of Cronobacter sakazakii and two strains of Yersinia enterocolitica were also isolated. A substantially higher rate of contamination by Bacillus cereus was observed in fermented food (82%) than in samples of meat (2%) and fish or seafood (5%). Seven Listeria spp. isolates were obtained from meat and fish or seafood samples. Approximately 39% of samples tested were found to be contaminated with Staphylococcus spp. (54 isolates). The rate of bacterial contamination of meat did not depend on the type of market. However, the contamination rate of Staphylococcus spp. in vegetables was higher in open markets than in supermarkets, and the contamination rate of Salmonella spp. and Staphylococcus spp. in fish or seafood samples purchased in open markets was likewise higher than in those purchased in supermarkets. Therefore, improvement of hygienic practices throughout the food chain may be required to reduce the risk of food poisoning.

The majority of seed sprout-related outbreaks have been associated with Escherichia coli O157:H7 and Salmonella. Therefore, we aimed to find an effective method to inactivate these organisms on seeds before sprouting. Treatment with 8.7% (v/v) acetic acid at 55°C for 2-3 h reduced the population of E. coli O157:H7 and Salmonella inoculated on alfalfa (Medicago sativa L.) and radish seeds (Raphanus sativus L.) by more than 5.0 log CFU/g, and a longer treatment time completely eliminated the E. coli O157:H7 population. The E. coli O157:H7 populations were reduced to an undetectable level with a gaseous acetic acid treatment for 48 h. After enrichment, no E. coli O157:H7 were found in the alfalfa and radish seeds (25 g). However, these treatments were unable to eliminate Salmonella in both seed types. No significant difference between the germination rates of treated alfalfa seeds and control seeds was found, and germination rates greater than 95% were obtained for the radish seeds. Although chlorine washing is commonly used for seed decontamination, chlorine washing at 200 and 20,000 ppm resulted in a reduction of pathogens by less than or equal to 3 log CFU/g. Therefore, these results suggested that gaseous acetic acid is more effective than chlorine washing in controlling pathogenic bacteria on sprout seeds.

The prevalence of foodborne pathogens or food spoilage bacteria in retailed foodstuffs that causes diarrheal diseases or quantity/quality loss of foods were determined in this study. Four categories of 137 raw food samples (meat, vegetable, fish or sea food and fermented food) and 133 soy bean curd (tofu) (packaged and unpackaged) were purchased randomly from 14 open markets and 7 supermarkets in Thailand from August 2010 to January 2012. 12 kinds of foodborne pathogens and food spoilage bacteria were identified using conventional culture methods and/or immunological/molecular biological methods. More than 85% of each raw food samples except for fermented foods was contaminated with coliform bacteria and 53% of 270 samples were contaminated with Escherichia coli. However, no E. coli O26, O157 or O111 strain was isolated except for one E. coli O157:H7 strain (stx 1 and 2 negative) from 173 E. coli isolates. 67% of meat samples were contaminated with Salmonella spp. In contrast, the contamination rate of Salmonella spp. in vegetable (5%), fermented food (9%) or tofu (4%) samples were comparatively low. The contamination rate of Salmonella spp. in meat, fish or sea food and tofu purchased in open markets were higher than those purchased from supermarkets. The frequently encountered Salmonella spp. isolated from all the samples was Salmonella Corvallis (9.6%) and S. Rissen (8.5%). Seven strains of Cronobacter sakazakii were isolate from 5 categories of foods except fermented foods. One strains of Yersinia enterocolitica serotype 0:5 were also isolated from tofu. Two Listeria monocytogenes strains were isolated from chicken and ground pork samples. The highest contamination rate of Bacillus cereus was observed in fermented food (82%). Ninety one Staphylococcus spp. including 1 S. aureus (coagulase negative) strains were isolated from all the collected samples. The contamination rate of Staphylococcus spp. in fish or sea food and vegetable purchased in open markets was likewise higher than those purchased in supermarkets. 79% of total sample was contaminated with Enterococcus spp. and 5% of the isolated Enterococcus spp. were able to grow on VR-EF antibiotic agar and were drug resistance strain. 100 and 34 Salmonella spp. isolates exhibited resistance to 1 to 30 kinds of antibiotics, in 15 antibiotics tested. These results suggested the implementation of good hygienic practices were required to reduce the risk of food poisoning and food spoilage loss.