{ "schema_version": "1.0", "level": "genus", "genus": "Cryptococcus", "overview": { "short": "Cryptococcus species are encapsulated, yeast-form fungi primarily affecting immunocompromised hosts.", "clinical_context": "Most commonly associated with pulmonary infections and meningoencephalitis, especially in HIV/AIDS and other immunosuppressed patients." }, "expected_fields": { "Gram Stain": "Variable", "Shape": "Yeast", "Motility": "Negative", "Capsule": "Positive", "Spore Formation": "Negative", "Haemolysis": "Negative", "Haemolysis Type": "None", "Media Grown On": [ "Sabouraud Dextrose Agar", "Blood Agar" ], "Colony Morphology": [ "Mucoid", "Cream", "Smooth" ], "Oxygen Requirement": "Aerobe", "Growth Temperature": "20//37", "Catalase": "Positive", "Oxidase": "Negative", "Indole": "Negative", "Urease": "Positive", "Citrate": "Negative", "Methyl Red": "Unknown", "VP": "Unknown", "H2S": "Negative", "DNase": "Negative", "ONPG": "Negative", "Coagulase": "Negative", "Gelatin Hydrolysis": "Negative", "Esculin Hydrolysis": "Negative", "Nitrate Reduction": "Negative", "NaCl Tolerant (>=6%)": "Negative", "Lipase Test": "Negative", "Lysine Decarboxylase": "Negative", "Ornithine Decarboxylase": "Negative", "Ornitihine Decarboxylase": "Negative", "Arginine dihydrolase": "Negative", "Glucose Fermentation": "Negative", "Lactose Fermentation": "Negative", "Sucrose Fermentation": "Negative", "Maltose Fermentation": "Negative", "Mannitol Fermentation": "Negative", "Sorbitol Fermentation": "Negative", "Xylose Fermentation": "Negative", "Rhamnose Fermentation": "Negative", "Arabinose Fermentation": "Negative", "Raffinose Fermentation": "Negative", "Trehalose Fermentation": "Negative", "Inositol Fermentation": "Positive", "Gas Production": "Negative", "TSI Pattern": "Unknown", "Colony Pattern": "Unknown", "Pigment": "None", "Motility Type": "None" }, "field_notes": { "Capsule": "Prominent polysaccharide capsule is a defining feature and key virulence factor.", "Urease": "Urease positivity is consistent across clinically relevant Cryptococcus species.", "Inositol Fermentation": "Positive reaction is characteristic and aids differentiation from other yeasts." }, "key_differentiators": [ { "field": "Capsule", "expected": "Positive", "distinguishes_from": ["Candida"], "notes": "Encapsulation separates Cryptococcus from most Candida species." }, { "field": "Urease", "expected": "Positive", "distinguishes_from": ["Candida"], "notes": "Urease activity is a key screening test for Cryptococcus." }, { "field": "Inositol Fermentation", "expected": "Positive", "distinguishes_from": ["Candida"], "notes": "Inositol utilization supports Cryptococcus identification." } ], "common_confusions": [ { "genus": "Candida", "reason": "Both are yeast-form fungi, but Candida lacks a capsule and is urease negative." }, { "genus": "Rhodotorula", "reason": "Some species share urease positivity but differ in pigmentation and capsule presence." } ], "when_to_question_identification": [ "Absence of capsule argues against Cryptococcus.", "Urease negativity suggests alternative yeast genera.", "Strong carbohydrate fermentation profile is inconsistent with Cryptococcus." ], "recommended_next_tests": [ { "test": "India ink preparation", "reason": "Demonstrates the characteristic polysaccharide capsule.", "api_kit": "Not applicable" }, { "test": "Urease test", "reason": "Rapid screening test for Cryptococcus.", "api_kit": "Christensen Urea Agar" }, { "test": "MALDI-TOF MS", "reason": "Accurate species-level identification.", "api_kit": "Not applicable" } ], "supported_species": [ "neoformans", "gattii", "laurentii" ] }