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Development of Clostridium difficile in vacuum packed meats stored at different temperatures

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Clostridium difficile is an anaerobic rod-shaped, spore–forming, causing diarrhea and pseudomembranous colitis with possible transmission of the disease associated with ingestion of food. The minimum temperature for food multiplication is not yet described, so the objective of the study was to evaluate the behavior of C. difficile in vacuum-packed meats kept at different temperatures. Samples of cooked vacuum packed beef were inoculated with 104 - 105 CFU/g of C. difficile (VPI 10463) and stored at 7 and 15 ± 1 ºC for 35 and 18 days, respectively. Vegetative cell and spore counts were performed by pour plate technique in Reinforced Clostridial Agar incubated at 37 ºC for 48 hours in anaerobic conditions. Data were analyzed using ANOVA and Tukey test. A significative difference (p<0.05) in the growth rate between storage temperature 7 and 15 ºC was observed. At 7 ºC, an increase of 1.05 log CFU/g in C. difficile spore counts over a period of 35 days was observed with counting 5.42 log CFU/g, and a reduction of 2.50 log CFU/g in vegetative cells, decreasing from 4.81 log CFU/g (day 0) to 2.31 log CFU/g (day 35), was observed. At 15 ºC, the vegetative cells grew 1.7 log CFU/g until day 7, then decreased 2.32 log CFU/g until day 18 and the spores decreased slightly and then remained constant until day 12 (3.59 log CFU/g), from which an increase was observed up to day 18 (5.46 log CFU/g). Thus, the capacity of C. difficile of multiply at 15 ºC and produce spores at 7 ºC in vacuum-packed cooked meat, may represent a risk factors of foodborne disease to humans.