Related Experiment Videos
Evaluation and modifications of media for enumeration of Clostridium perfringens
Abstract:
The suitability of the Shahidi-Ferguson perfringens, TSC (tryptose-sulfite-cycloserine), and oleandomycin-polymyxin-sulfadiazine perfringens agars for presumptive enumeration of Clostridium perfringens was tested. Of these, the TSC agar was the most satisfactory. The TSC agar method was improved by eliminating the egg yolk and using pour plates. The modified method allowed quantitative recoveries of each of 71 C. perfringens strains tested and is recommended. For confirmation of C. perfringens, the nitrite test in nitrate motility agar was unreliable, particularly after storage of the medium for a few days. In contrast, positive nitrite reactions were obtained consistently when nitrate motility agar was supplemented with glycerol and galactose.
Insights
Tryptose-sulfite-cycloserine (TSC) agar is the most effective for enumerating Clostridium perfringens. Enhancements to TSC agar and nitrate motility agar improve reliable detection of this bacterium.
Area of Science:
- Microbiology
- Food Safety
- Bacteriology
Background:
- Accurate enumeration of Clostridium perfringens is crucial for food safety.
- Several selective agars exist for presumptive identification, but their efficacy varies.
- Reliable confirmation methods are needed to complement presumptive testing.
Purpose of the Study:
- To evaluate the suitability of Shahidi-Ferguson perfringens, TSC, and oleandomycin-polymyxin-sulfadiazine perfringens agars for Clostridium perfringens enumeration.
- To optimize the TSC agar method for improved quantitative recovery.
- To assess the reliability of the nitrite test in nitrate motility agar for confirmation and explore enhancement strategies.
Main Methods:
- Comparative analysis of three selective agars: Shahidi-Ferguson perfringens, TSC, and oleandomycin-polymyxin-sulfadiazine perfringens.
- Modification of the TSC agar by removing egg yolk and employing pour plates.
- Testing the modified TSC method with 71 Clostridium perfringens strains.
- Evaluation of the nitrite test in nitrate motility agar, including assessment of medium storage effects.
- Supplementation of nitrate motility agar with glycerol and galactose to improve nitrite test performance.
Main Results:
- TSC agar demonstrated the highest satisfactory performance for presumptive enumeration of Clostridium perfringens.
- The modified TSC agar method, utilizing pour plates without egg yolk, enabled quantitative recovery of all 71 tested Clostridium perfringens strains.
- The standard nitrite test in nitrate motility agar proved unreliable for confirmation, especially with stored media.
- Supplementing nitrate motility agar with glycerol and galactose consistently yielded positive nitrite reactions, enhancing reliability.
Conclusions:
- The modified TSC agar method is recommended for reliable quantitative enumeration of Clostridium perfringens.
- Supplementation of nitrate motility agar with glycerol and galactose significantly improves the accuracy of the nitrite test for Clostridium perfringens confirmation.