Bacterial Contamination in Retail Foods Purchased in Thailand

The loss of quality or quantity of raw foods caused by spoilage bacteria is a major problem, especially in developing countries. Evaluation of the frequency and level of bacterial contamination and/or identification of the contaminating bacteria are keys to solving this problem. The objective of this study was to evaluate the prevalence and types of contaminating bacteria in retail foodstuffs in Thailand. Foods in four categories (137 samples total) including meat (51 samples), vegetables (38 samples), fish or seafood (37 samples) and fermented food (11 samples) were purchased randomly from seven different open markets and seven supermarkets in Thailand from August 2010 to March 2011. Indicator bacteria of fecal contamination or other naturally contaminating bacteria were isolated and identified. More than 90% of each category of collected retail meat, vegetables and fish or seafood was contaminated with coliform bacteria. The contamination rate of fecal coliform bacteria, Staphylococcus spp. and lactic acid bacteria was higher in vegetables from open markets than those from supermarkets, and the contamination rate of Staphylococcus spp. was likewise higher in fish or seafood samples purchased from open markets than those from supermarkets. Improvement in hygienic practices throughout the food distribution may reduce the risk of food poisoning and spoilage of foods purchased in Thai markets.