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Comparison of media for the enumeration of Clostridium perfringens
Abstract:
For the enumeration of viable vegetative cells and spores of Clostridium perfringens, noncommercial (laboratory prepared) sulfite-polymyxin-sulfadiazine (SPS) agar, tryptone-sulfite-neomycin (TSN) agar, and Shahidi-Ferguson-perfringens (SFP) agar were statistically compared to SPS agar without antibiotics. The selectivities of these four media were also evaluated on the basis of their ability to inhibit the growth of pure cultures of a variety of other organisms. The average recovery of vegetative cells of 10 strains of C. perfringens with SFP agar was not significantly higher than with SPS agar with 10(4) organisms per g, but with 10(6) organisms per g it yielded significantly higher recoveries than SPS agar. TSN agar yielded significantly lower recoveries at both inoculum levels. SFP agar gave significantly higher recoveries of spores than SPS and TSN agars. Average plate counts of spores in SFP agar were 75% as high as in SPS agar without antibiotics, but only 45% of the spores grew in SPS agar and 25% in TSN agar. TSN agar was the most selective of the three media, but the selectivity of SPS agar approached that of TSN agar under the test conditions. SFP agar, which was the least selective of the media, allowed growth to some extent of nearly all of the facultative anaerobes tested.
Insights
Shahidi-Ferguson-perfringens (SFP) agar showed superior recovery of Clostridium perfringens spores compared to other media. Tryptone-sulfite-neomycin (TSN) agar offered the highest selectivity, while SFP agar was least selective.
Area of Science:
- Microbiology
- Food Safety
- Clinical Diagnostics
Background:
- Accurate enumeration of Clostridium perfringens is crucial for food safety and clinical diagnostics.
- Evaluating selective culture media is essential for reliable detection and quantification.
Purpose of the Study:
- To compare the efficacy of laboratory-prepared sulfite-polymyxin-sulfadiazine (SPS), tryptone-sulfite-neomycin (TSN), and Shahidi-Ferguson-perfringens (SFP) agars for enumerating Clostridium perfringens.
- To assess the selectivity of these media against other common organisms.
Main Methods:
- Statistical comparison of noncommercial SPS, TSN, and SFP agars against a reference SPS agar.
- Evaluation of media selectivity using pure cultures of various microorganisms.
- Quantification of viable vegetative cells and spores of C. perfringens at different inoculum levels.
Main Results:
- SFP agar yielded significantly higher recoveries of C. perfringens spores than SPS and TSN agars.
- At high inoculum levels (10^6 organisms/g), SFP agar showed significantly better recovery of vegetative cells than SPS agar.
- TSN agar demonstrated the highest selectivity, effectively inhibiting non-target organisms, while SFP agar was the least selective.
Conclusions:
- SFP agar is a promising medium for enhanced recovery of Clostridium perfringens spores.
- The choice of medium depends on the specific application, balancing recovery rates with selectivity requirements.
- Further optimization of selective agents may improve the performance of SFP and SPS agars.