{ "schema_version": "1.0", "level": "genus", "genus": "Acidaminococcus", "overview": { "short": "Acidaminococcus species are Gram-negative, anaerobic cocci belonging to the class Negativicutes, characterized by amino acid fermentation rather than carbohydrate metabolism.", "clinical_context": "Part of the normal gastrointestinal flora and occasionally isolated from polymicrobial anaerobic infections." }, "expected_fields": { "Gram Stain": "Negative", "Shape": "Cocci", "Motility": "Negative", "Capsule": "Unknown", "Spore Formation": "Negative", "Haemolysis": "Negative", "Haemolysis Type": "None", "Media Grown On": [ "Blood Agar" ], "Colony Morphology": [ "Small", "Grey", "Convex" ], "Oxygen Requirement": "Obligate Anaerobe", "Growth Temperature": "35//37", "Catalase": "Negative", "Oxidase": "Negative", "Indole": "Negative", "Urease": "Negative", "Citrate": "Negative", "Methyl Red": "Negative", "VP": "Negative", "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": "Negative", "Gas Production": "Negative", "TSI Pattern": "K/K", "Colony Pattern": "Unknown", "Pigment": "None", "Motility Type": "None" }, "field_notes": { "Gram Stain": "Despite being Gram-negative, Acidaminococcus belongs to a lineage phylogenetically related to Gram-positive bacteria.", "Glucose Fermentation": "Species do not ferment carbohydrates and instead utilize amino acids for energy.", "Oxygen Requirement": "Strict anaerobiosis is a defining characteristic." }, "key_differentiators": [ { "field": "Oxygen Requirement", "expected": "Obligate Anaerobe", "distinguishes_from": ["Neisseria", "Veillonella"], "notes": "Strict anaerobic growth separates Acidaminococcus from aerobic Gram-negative cocci." }, { "field": "Shape", "expected": "Cocci", "distinguishes_from": ["Bacteroides", "Fusobacterium"], "notes": "Coccoid morphology helps differentiate from anaerobic Gram-negative rods." }, { "field": "Glucose Fermentation", "expected": "Negative", "distinguishes_from": ["Veillonella"], "notes": "Lack of carbohydrate fermentation supports Acidaminococcus." } ], "common_confusions": [ { "genus": "Veillonella", "reason": "Both are anaerobic Gram-negative cocci isolated from similar clinical contexts." }, { "genus": "Megasphaera", "reason": "Phylogenetic relatedness within Negativicutes." } ], "when_to_question_identification": [ "Aerobic or facultative growth argues against Acidaminococcus.", "Carbohydrate fermentation suggests Veillonella.", "Rod-shaped morphology excludes this genus." ], "recommended_next_tests": [ { "test": "Anaerobic growth confirmation", "reason": "Essential for correct genus assignment." }, { "test": "Amino acid fermentation profiling", "reason": "Characteristic metabolic feature of Acidaminococcus." }, { "test": "MALDI-TOF MS", "reason": "Recommended due to biochemical inertness and rarity." } ], "supported_species": [ "fermentans", "intestini" ] }