Clostridium Perfringens In Beef Research Articles

The effect of low-temperature long-time (LTLT) cooking on survival of potentially pathogenic Clostridium perfringens in beef

Low-temperature long-time (LTLT) cooking may lead to risk of potential survival of pathogenic bacteria such as Clostridium perfringens in cooked meat. In this study, the effect of LTLT cooking on C. perfringens was investigated at temperatures commonly used by caterers. Brain heart infusion broth (BHIB) and meat cubes in pouches (vacuumed or non-vacuumed) were inoculated with C. perfringens (NCTC 8238) and heated at temperatures of 48 °C, 53 °C, 55 °C, 60 °C and 70 °C. The viability of C. perfringens in BHIB and meat was monitored using plate counting and the D-value of each thermal treatment was determined. The recovery of C. perfringens after thermal treatment was assessed using optical density measurements. Flow cytometry analysis was used to assess the physiological status (death/injury) of C. perfringens cells in BHIB. The results showed that the required log reduction (6-log) of C. perfringens can be achieved at 55 °C but not at 48 °C or 53 °C. The D-values at all temperatures were higher in meat compared to BHIB while the D-value at 55 °C was higher in non-vacuum compared to vacuum sealed meat. C. perfringens cells were able to recover and grow to pathogenic levels when thermal treatment was unable to achieve the required 6-log reduction. In BHIB, percentage of dead cells increased gradually at 48 °C, 53 °C and 55 °C while an immediate increase (>95%) was observed at 60 °C and 70 °C. These results are important to food safety authorities allowing to set the time-temperature combinations to be used in LTLT cooking to obtain safe meat.

Prevalence and toxin type of Clostridium perfringens in beef from four different types of meat markets in Seoul, Korea.

Beef is the primary source of foodborne poisoning caused by Clostridium perfringens. We investigated the prevalence of C. perfringens in retail beef from four different types of meat markets in Seoul using a standard culture method and real-time PCR assay. From June to September 2015, 82 beef samples were collected from 6 department stores (n=12), 14 butcher shops (n=28), 16 traditional markets (n=32), and 5 supermarkets (n=10). The culture method and real-time PCR assay revealed that 4 (4.88%) and 10 (12.20%) samples were positive for C. perfringens, respectively. The beef purchased from the department store showed the highest prevalence (16.67%), followed by the traditional market (3.12%), butcher shop (3.57%), and supermarket (0%) (p>0.05). All isolates were type A and negative for the enterotoxin gene. In conclusion, the real-time PCR assay used in this study could be useful for rapid detection and screening of C. perfringens in beef.

Amount of enterotoxigenic Clostridium perfringens in meat detected by nested PCR

The incidence and quantity of enterotoxigenic Clostridium perfringens in beef, pork, and chicken meat were determined and compared with that of the total enterotoxigenic and nonenterotoxigenic C. perfringens. The method for the detection and quantification of enterotoxigenic C. perfringens consisted of a combination of the most probable number (MPN) method and a nested polymerase chain reaction after culturing of the sample. The results obtained by this method for inoculated meat samples were significantly correlated with those obtained by the plate count method. When the method was applied to the detection and quantification of enterotoxigenic C. perfringens found in randomly selected meat samples, the organism was found in 2% of the beef pieces (<10 2 MPN/100 g) and 12% of the chicken pieces (<10 2–4.3×10 2 MPN/100 g) out of the 50 pieces of each meat tested. No enterotoxigenic C. perfringens was found in pork. Total C. perfringens was found in 16% of the beef (<10 2–4.3×10 2 MPN/100 g), 10% of the pork (<10 2 MPN/100 g), and 84% of the chicken (<10 2–9.3×10 3 MPN/100 g) when 50 pieces of each meat was tested by the conventional MPN method. As shown in the above methods, the majority of cells were not enterotoxigenic cells in the population of C. perfringens. A small number of enterotoxigenic cells of C. perfringens co-existed with a large number of nonenterotoxigenic cells in the same meat sample.

MEMBRANE FILTRATION IMMUNOSTAINING TECHNIQUE FOR DETECTION AND QUANTITATION OF ENTEROTOXIGENIC CLOSTRIDIUM PERFRINGENS IN PRECOOKED BEEF 1

ABSTRACTA membrane filtration‐immunostaining technique was developed for detection and direct enumeration of enterotoxigenic Clostridium perfringens in beef. The procedure combined a microcolony technique with an indirect alkaline phosphatase conjugated antibody visualization system. Precooked ground beef samples containing enterotoxigenic C. perfringens cells were diluted in phosphate buffered saline containing 0.1% Tween 80 and filtered through a 0.45 μm cellulose nitrate filter. The membranes were placed onto the surface of solid Duncan and Strong medium and incubated anaerobically for 4–18 h at 37C. The membranes were sequentially overlaid with C. perfringens anti‐enterotoxin and an alkaline phosphatase conjugated antibody resulting in a chromogenic reaction that enabled detection and enumeration. The membrane immunostaining technique proved to be sensitive enough to detect as low as 2 CFU/g of enterotoxigenic C. perfringens.