Fig. 1.
![Variability summary for RD [%].](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64727c1c215d2f6c89dc9f62/j_pjm-2023-039_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKBRROV245%2F20260217%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260217T220958Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEIn%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaDGV1LWNlbnRyYWwtMSJHMEUCIQC9HBJ9dX14Ef7j1GyvLOIzkM3nOS9lws8hFklZ7kcI2gIgdNp06A6rKJelUAJwXqC2HAhkyT4oJSvti%2FEb6IG9b3sqvQUIUxACGgw5NjMxMzQyODk5NDAiDELvb2yjDoKkFPKFmSqaBXR97APdarYZqSBVHTSFQ2nCYduRlo9qqSrQBZ1gEOKMUFb090hysT%2BRiKi%2B7ZZQlrYqcXmUtLZYeXgvpY%2FWio5JwTJomyZik0891riGcD5I3w1HZIyLizhRVoPnvTccIBeIX0aZA2FiSUHDc4Oh%2FAIjvAwobwY%2FSlQ1GkXjrcgrDOksnfn%2Fz2grzcOfq2QLhIKSQ6BgZvpf%2F8J0DJphuGvjkZkH9XbNUyJMPxvAhKFHRIyptYitrc%2BfyKANBHgQTIaJy8N738VEiXqU5URaDZptXg5XobSvLFNq5L0f6pTgGlGXL4RZC2HH5Z6dJe9dYePLfMxsLoG5BQJruPxf00fm3YxeSxzDaqcg3pPSqGGmprNbh2%2F%2Bcgg%2BODjBTkrwG%2B660an0mVajiALE5C2xlaFu2hfn8PMpnRodtUX1gXwsQ6OBqyrcYWenKRr%2FTYir3XYVrosLHLNw9xojR%2FZonUZF1ErDOXeyNsIWtROxFYDe7Z66PFo09dUjypBy9RmJVlly%2Fu5nsGl4XzKG0lKX5PQJeKCUXd30%2B5Iq1cRlctMqvt0xvnTx%2BfbrFD8hGVBum0g4SW9WNang665Ho9N4JvVXK5wy5eFI%2BJMOYeXyU3F%2F17J7gngkbWd3DDO0zc7y383aupxgykQ8J30YTfg1ApQsabbo7BDW4xcGtKxZd0SOBcwQE4hSHnf7xPmoKgJMXRFJyzWc5KQycVEZUFaMyLxel8jKz%2FgnILXBT51qGspaaDhqe8%2Bxz%2Friob%2Bv%2Bj2MIo9PlzPRQJ8B07GaCAuBObJLWnTvtQlpegIeQx%2BLu%2FQxdYDNLhYrrbUYe5QxZKKH%2BKN0vdxby6xcIFmjiqYGFqxOk8iZfIqubMAcZjd6KNqtWzd8KTz1Wq0HdDCVyNLMBjqxAVuQMs3oVHP4PLGhIAiG1O3GiakJ7ncG0p80lGZW1Dxa5BlrHx%2BngAmkTxjiJbIEcdDHwecyESye4i06crEQCM4vwixgwbZhUbCqfhtr5v2fXSUSKzTw10h19yUnYh%2Fj90zMM0Cgygb%2F5o7tx%2FlP%2FnsiIVWR2v1n2n0xA1pb%2FhoG9V4mDbsE3KGDoEPKn9LaiiOQ6n5DudH%2FccJUl7dpTz%2Ftzr6ma3bwYLzxpdNxZ59TOA%3D%3D&X-Amz-Signature=044eb29615b5cdc6020139b0a6416baa64479615f8ab391c888b535ca4d3bfea&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Confirmatory tests for Clostridium perfringens according to Directive 98/83/EC_
| Feature | Clostridium perfringens |
|---|---|
| Sucrose fermentation | sucrose-positive – yellow and matte colonies |
| Possess acid phosphatase | change of color of the colony from yellow to pink in ammonium hydroxide vapors |
Confirmatory tests for Clostridium perfringens according to ISO/CD 6461-2:2002_
| Feature | Clostridium perfringens |
|---|---|
| Reduction of sulphites to sulphides | black or grey colonies |
| Motility | none |
| Reduction of nitrate to nitrites | orange/red-colored medium after the addition of the Nessler reagent |
| Lactose fermentation | orange or yellow-colored medium with lactose (acidification of the medium and gas formation) |
| Protease formation | gelatine liquefaction |
Comparison of the results of confirmation tests for Clostridium perfringens_
| Characteristics of Clostridium perfringens presumptive confirmed colonies | TSC ISO/CD 6461-2:2002 | mCP Directive 98/83/EC |
|---|---|---|
| Number of all confirmed colonies | 466 | 381 |
| Typical colonies, confirmed positive (true positive) | 150 | 107 |
| Atypical colonies, confirmed positive (false negative) | 33 | 11 |
| Typical colonies, confirmed negative (false positive) | 196 | 79 |
| Atypical colonies, confirmed negative (true negative) | 87 | 184 |
| Typical colonies, non-detection error | 0.18 | 0.09 |
Comparison of performance parameters of procedures used for detection of Clostridiun perfringens in water samples_
| Performance parameters | TSC ISO/CD 6461-2:2002 | mCP Directive 98/83/EC |
|---|---|---|
| Sensitivity | 82.0% | 90.7% |
| Specificity | 30.7% | 70.0% |
| Selectivity | 32.2% | 28.1% |
| False negative rate | 27.5% | 5.6% |
| False positive rate | 56.6% | 42.5% |
| Efficiency | 50.9% | 76.4% |