{ "schema_version": "1.0", "level": "genus", "genus": "Erysipelothrix", "overview": { "short": "Erysipelothrix species are Gram-positive, facultatively anaerobic, non-spore-forming short rods commonly associated with zoonotic exposure.", "clinical_context": "Most notably associated with erysipeloid infections following occupational exposure to animals, fish, or animal products." }, "expected_fields": { "Gram Stain": "Positive", "Shape": "Short Rods", "Motility": "Negative", "Capsule": "Negative", "Spore Formation": "Negative", "Haemolysis": "Variable", "Haemolysis Type": "Variable", "Media Grown On": [ "Blood Agar" ], "Colony Morphology": [ "Small", "Grey", "Translucent", "Smooth" ], "Oxygen Requirement": "Facultative Anaerobe", "Growth Temperature": "20//42", "Catalase": "Negative", "Oxidase": "Negative", "Indole": "Negative", "Urease": "Negative", "Citrate": "Negative", "Methyl Red": "Positive", "VP": "Negative", "H2S": "Positive", "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": "Positive", "Lactose Fermentation": "Negative", "Sucrose Fermentation": "Variable", "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": "Negative", "Gas Production": "Negative", "TSI Pattern": "Unknown", "Colony Pattern": "Unknown", "Pigment": "None", "Motility Type": "None" }, "field_notes": { "H2S": "Distinctive H2S production on TSI or iron-containing media helps differentiate Erysipelothrix from other Gram-positive rods.", "Catalase": "Catalase-negative, distinguishing it from many Gram-positive rods.", "Haemolysis": "May be weak or variable; not a reliable primary discriminator." }, "key_differentiators": [ { "field": "H2S", "expected": "Positive", "distinguishes_from": ["Listeria", "Corynebacterium"], "notes": "Rare H2S production among Gram-positive rods." }, { "field": "Catalase", "expected": "Negative", "distinguishes_from": ["Listeria"], "notes": "Separates Erysipelothrix from catalase-positive short rods." } ], "common_confusions": [ { "genus": "Listeria", "reason": "Shared short rod morphology and facultative anaerobic growth." }, { "genus": "Corynebacterium", "reason": "Gram-positive rod morphology with skin-associated isolates." } ], "when_to_question_identification": [ "Catalase positivity argues against Erysipelothrix.", "Motility suggests Listeria.", "Absence of H2S production should prompt reconsideration." ], "recommended_next_tests": [ { "test": "H2S detection on TSI or iron-containing media", "reason": "Key genus-level discriminator.", "api_kit": "API Coryne" }, { "test": "Motility testing", "reason": "Non-motility helps exclude Listeria.", "api_kit": "Manual wet mount" }, { "test": "MALDI-TOF MS", "reason": "Definitive identification and species-level resolution.", "api_kit": "Not applicable" } ], "supported_species": [ "rhusiopathiae", "tonsillarum" ] }