Micro & Immunology · single question
Which bacteria is found in MOLAR-INCISOR PATTERN periodontitis (Localized Aggressive Periodontitis)?
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Correct answer: A. Aggregatibacter actinomycetemcomitans (Aa)
Aggregatibacter actinomycetemcomitans (Aa) (A) is the primary pathogen in Localized Aggressive Periodontitis (LAP) — now classified as Localized Stage III/IV, Grade C periodontitis.
• Aa has unique virulence factors: leukotoxin (kills PMNs), cytolethal distending toxin, bacteriocins, bone resorption factors.
• LAP features: affects first molars and incisors (molar-incisor pattern), otherwise healthy young patients (typically <30 years), rapid bone loss, often familial clustering, minimal calculus.
• Treatment: scaling/root planing + systemic amoxicillin + metronidazole (combination specifically effective against Aa).
• Porphyromonas gingivalis: red complex — generalized periodontitis in adults.
• Aa is Gram-negative, facultatively anaerobic, capnophilic (grows well with CO2).
• Aa has unique virulence factors: leukotoxin (kills PMNs), cytolethal distending toxin, bacteriocins, bone resorption factors.
• LAP features: affects first molars and incisors (molar-incisor pattern), otherwise healthy young patients (typically <30 years), rapid bone loss, often familial clustering, minimal calculus.
• Treatment: scaling/root planing + systemic amoxicillin + metronidazole (combination specifically effective against Aa).
• Porphyromonas gingivalis: red complex — generalized periodontitis in adults.
• Aa is Gram-negative, facultatively anaerobic, capnophilic (grows well with CO2).
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