{ "schema_version": "1.0", "level": "species", "genus": "Clostridioides", "species": "difficile", "overview": { "short": "Clostridioides difficile is a Gram-positive, anaerobic, spore-forming rod and a leading cause of antibiotic-associated diarrhoea and pseudomembranous colitis.", "clinical_context": "Classically associated with recent antibiotic exposure, healthcare settings, and detection of toxin production." }, "expected_fields": { "Gram Stain": "Positive", "Shape": "Rods", "Motility": "Positive", "Capsule": "Negative", "Spore Formation": "Positive", "Haemolysis": "Variable", "Haemolysis Type": "Variable", "Media Grown On": [ "Blood Agar", "CCFA Agar" ], "Colony Morphology": [ "Irregular", "Flat", "Grey" ], "Oxygen Requirement": "Anaerobic", "Growth Temperature": "25//42", "Catalase": "Negative", "Oxidase": "Negative", "Indole": "Negative", "Urease": "Negative", "Citrate": "Negative", "Methyl Red": "Positive", "VP": "Negative", "H2S": "Negative", "DNase": "Negative", "ONPG": "Negative", "Coagulase": "Negative", "Gelatin Hydrolysis": "Variable", "Esculin Hydrolysis": "Variable", "Nitrate Reduction": "Negative", "NaCl Tolerant (>=6%)": "Negative", "Lipase Test": "Negative", "Lysine Decarboxylase": "Negative", "Ornithine Decarboxylase": "Negative", "Ornitihine Decarboxylase": "Negative", "Arginine dihydrolase": "Negative", "Glucose Fermentation": "Positive", "Lactose Fermentation": "Variable", "Sucrose Fermentation": "Variable", "Maltose Fermentation": "Variable", "Mannitol Fermentation": "Negative", "Sorbitol Fermentation": "Negative", "Xylose Fermentation": "Variable", "Rhamnose Fermentation": "Negative", "Arabinose Fermentation": "Variable", "Raffinose Fermentation": "Negative", "Trehalose Fermentation": "Variable", "Inositol Fermentation": "Negative", "Gas Production": "Variable", "TSI Pattern": "Unknown", "Colony Pattern": "Unknown", "Pigment": "None", "Motility Type": "Variable" }, "species_markers": [ { "field": "Motility", "value": "Positive", "importance": "medium", "notes": "Motility supports C. difficile in context, but is not exclusive among anaerobic rods." }, { "field": "Indole", "value": "Negative", "importance": "medium", "notes": "Indole negativity helps distinguish from certain other clostridial anaerobes." }, { "field": "Media Grown On", "value": "CCFA Agar", "importance": "high", "notes": "Growth on selective media supports isolation/confirmation in appropriate clinical context." } ], "common_confusions": [ { "species": "Clostridioides mangenotii", "reason": "Same genus and broad anaerobic spore-forming profile; requires higher-resolution confirmation." }, { "genus": "Clostridium", "reason": "Many species are anaerobic spore-forming rods with overlapping biochemical reactions." } ], "when_to_question_identification": [ "Lack of anaerobic growth suggests an aerobe/facultative organism rather than Clostridioides.", "Non-spore-forming phenotype argues strongly against C. difficile.", "If clinical context is not gastrointestinal/antibiotic-associated, consider alternative anaerobes." ], "recommended_next_tests": [ { "test": "Toxin A/B detection (EIA) or GDH + toxin algorithm", "reason": "Toxin detection is central to clinically relevant identification of toxigenic C. difficile.", "api_kit_example": "C. difficile GDH + toxin A/B rapid immunoassay kits (varies by lab supplier)." }, { "test": "NAAT (PCR) for toxin genes (e.g., tcdB)", "reason": "High sensitivity confirmation for toxigenic strains when algorithm indicates.", "api_kit_example": "C. difficile toxin gene NAAT/PCR assay kits (platform-dependent)." }, { "test": "MALDI-TOF MS", "reason": "Reliable organism identification; toxin status still requires toxin/NAAT testing." } ] }