data/rag/knowledge_base/Aggregatibacter/genus.json

{
  "schema_version": "1.0",
  "level": "genus",
  "genus": "Aggregatibacter",

  "overview": {
    "short": "Aggregatibacter species are fastidious, Gram-negative coccobacilli within the Pasteurellaceae family, commonly associated with oral flora and endocarditis.",
    "clinical_context": "Members of the HACEK group; most frequently implicated in infective endocarditis and periodontal disease."
  },

  "expected_fields": {
    "Gram Stain": "Negative",
    "Shape": "Short Rods",
    "Motility": "Negative",
    "Capsule": "Variable",
    "Spore Formation": "Negative",
    "Haemolysis": "Negative",
    "Haemolysis Type": "None",
    "Media Grown On": [
      "Blood Agar",
      "Chocolate Agar"
    ],
    "Colony Morphology": [
      "Small",
      "Grey",
      "Translucent"
    ],
    "Oxygen Requirement": "Facultative Anaerobe",
    "Growth Temperature": "35//37",
    "Catalase": "Variable",
    "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": "Variable",
    "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": {
    "Shape": "Often described as coccobacilli microscopically; normalized here as Short Rods.",
    "Growth Requirements": "Many species are fastidious and may require enriched media such as chocolate agar.",
    "Catalase": "Catalase reactions vary by species."
  },

  "key_differentiators": [
    {
      "field": "Motility",
      "expected": "Negative",
      "distinguishes_from": ["Haemophilus"],
      "notes": "Aggregatibacter species are non-motile, helping distinguish them from some Haemophilus species."
    },
    {
      "field": "Oxidase",
      "expected": "Negative",
      "distinguishes_from": ["Neisseria", "Moraxella"],
      "notes": "Oxidase negativity helps rule out oxidase-positive Gram-negative cocci."
    },
    {
      "field": "Growth Characteristics",
      "expected": "Fastidious",
      "distinguishes_from": ["Enterobacterales"],
      "notes": "Poor growth on MacConkey Agar helps separate Aggregatibacter from enteric Gram-negative rods."
    }
  ],

  "common_confusions": [
    {
      "genus": "Haemophilus",
      "reason": "Shared family (Pasteurellaceae) and similar fastidious growth requirements."
    },
    {
      "genus": "Cardiobacterium",
      "reason": "Both are HACEK organisms associated with endocarditis."
    }
  ],

  "when_to_question_identification": [
    "Robust growth on MacConkey Agar argues against Aggregatibacter.",
    "Oxidase positivity suggests Neisseria or Moraxella.",
    "Strong lactose fermentation is inconsistent with Aggregatibacter."
  ],

  "recommended_next_tests": [
    {
      "test": "Growth factor requirement testing",
      "reason": "Helps distinguish Aggregatibacter from Haemophilus species."
    },
    {
      "test": "Extended incubation",
      "reason": "HACEK organisms often grow slowly and may require prolonged incubation."
    },
    {
      "test": "MALDI-TOF MS",
      "reason": "Recommended due to fastidious growth and biochemical overlap."
    }
  ],

  "supported_species": [
    "actinomycetemcomitans",
    "aphrophilus",
    "segregatus"
  ]
}