{ "schema_version": "1.0", "level": "genus", "genus": "Aerococcus", "overview": { "short": "Aerococcus species are Gram-positive cocci that often appear in clusters or tetrads and resemble streptococci or staphylococci on initial examination.", "clinical_context": "Associated with urinary tract infections, bacteremia, endocarditis, and invasive infections, particularly in elderly or immunocompromised patients." }, "expected_fields": { "Gram Stain": "Positive", "Shape": "Cocci", "Motility": "Negative", "Capsule": "Variable", "Spore Formation": "Negative", "Haemolysis": "Variable", "Haemolysis Type": "Variable", "Media Grown On": [ "Blood Agar" ], "Colony Morphology": [ "Small", "Grey", "Alpha-haemolytic or Non-haemolytic" ], "Oxygen Requirement": "Facultative Anaerobe", "Growth Temperature": "30//37", "Catalase": "Negative", "Oxidase": "Negative", "Indole": "Negative", "Urease": "Negative", "Citrate": "Negative", "Methyl Red": "Unknown", "VP": "Unknown", "H2S": "Negative", "DNase": "Negative", "ONPG": "Unknown", "Coagulase": "Negative", "Gelatin Hydrolysis": "Negative", "Esculin Hydrolysis": "Negative", "Nitrate Reduction": "Negative", "NaCl Tolerant (>=6%)": "Negative", "Lipase Test": "Negative", "Lysine Decarboxylase": "Unknown", "Ornithine Decarboxylase": "Unknown", "Ornitihine Decarboxylase": "Unknown", "Arginine dihydrolase": "Negative", "Glucose Fermentation": "Positive", "Lactose Fermentation": "Variable", "Sucrose Fermentation": "Variable", "Maltose Fermentation": "Variable", "Mannitol Fermentation": "Negative", "Sorbitol Fermentation": "Negative", "Xylose Fermentation": "Negative", "Rhamnose Fermentation": "Unknown", "Arabinose Fermentation": "Negative", "Raffinose Fermentation": "Unknown", "Trehalose Fermentation": "Variable", "Inositol Fermentation": "Negative", "Gas Production": "Negative", "TSI Pattern": "Unknown", "Colony Pattern": "Unknown", "Pigment": "None", "Motility Type": "None" }, "field_notes": { "Catalase": "Typically catalase-negative, but weak or pseudo-positive reactions may occur.", "Haemolysis": "Most species are alpha-haemolytic or non-haemolytic on blood agar.", "Shape": "Often described as cocci in tetrads or clusters, which can mimic staphylococci." }, "key_differentiators": [ { "field": "Catalase", "expected": "Negative", "distinguishes_from": ["Staphylococcus"], "notes": "Catalase negativity helps separate Aerococcus from staphylococci." }, { "field": "NaCl Tolerant (>=6%)", "expected": "Negative", "distinguishes_from": ["Enterococcus"], "notes": "Lack of growth in high salt differentiates Aerococcus from enterococci." }, { "field": "Haemolysis", "expected": "Variable", "distinguishes_from": ["Streptococcus"], "notes": "Haemolysis pattern combined with colony morphology aids differentiation." } ], "common_confusions": [ { "genus": "Streptococcus", "reason": "Similar Gram-positive cocci morphology and haemolysis patterns." }, { "genus": "Enterococcus", "reason": "Overlapping biochemical reactions in urinary isolates." }, { "genus": "Staphylococcus", "reason": "Clustered cocci appearance on Gram stain may be misleading." } ], "when_to_question_identification": [ "Catalase-positive reaction suggests Staphylococcus.", "Growth in 6.5% NaCl suggests Enterococcus.", "Beta-haemolysis with streptococcal morphology suggests Streptococcus." ], "recommended_next_tests": [ { "test": "Catalase test (repeat)", "reason": "Weak reactions may require confirmation." }, { "test": "NaCl tolerance (6.5%)", "reason": "Useful for exclusion of Enterococcus." }, { "test": "MALDI-TOF MS", "reason": "Preferred method for accurate genus and species identification." } ], "supported_species": [ "urinae", "viridans", "sanguinicola", "christensenii" ] }