Example 4 - Direct and indirect detection of Clostridioides difficile

This example illustrates the highly specific diagnostics for Clostridioides difficile using various methods for toxin detection, glutamate dehydrogenase detection, and culture detection.

The methods illustrated in this example are:

• Immunoassay
• Cytotoxicity test
• Real-time PCR Pathogen-specific culture (anaerobic toxigenic culture)

Since a pathogen-specific culture method is used for the detection of Clostridioides difficile, a LOINC code specific to the analyte (the "component" axis) is also used.

All LOINC codes published at the time of this pilot phase for the direct or indirect detection of Clostridioides difficile contain "stool" as the specimen (the "system" axis). Consequently, in accordance with the defined rules for handling semantics in ARS, the aim is to apply for specimen-independent LOINC codes. Other specimen considered include intraoperative swabs or aspirates of intraperitoneal fluid in complicated cases.

This example shows that, on the one hand, an analyte-specific LOINC code was selected based on the diagnostic test used. If the same analyte, e.g., "Chlostridioides difficile toxin A+B", is detected using different methods, the same LOINC code is used, and the method applied is clearly described in "Observation.method" with a SNOMED code.

Conversely, if the same test method was used, the same SNOMED code can be used in "Observation.method", e.g., "703447009 | Enzyme immunoassay technique (qualifier value)", while the LOINC code describes different analytes detected using this method, e.g., "Clostridioides difficile toxin A+B" and "Clostridioides difficile glutamate dehydrogenase".