M181-4

Blood: Aggregatibacter actinomycetencomitans  – Shipped May 14, 2018

HISTORY

A simulated blood culture sample collected from 56 male with heart murmur was sent to category A laboratories.
Participants were expected to isolate, identify, and report Aggregatibacter actinomycetemcomitans.

MAIN EDUCATIONAL POINTS from M181-4

  1. HACEK group genera should be considered when patients present with presumptive infectious endocarditis, the blood culture may require 3 -4 days of incubation (although almost all isolates will grow with the usual 5 day incubation period of contemporary blood culture systems), and the Gram smear shows small gram negative coccobacillary morphotypes.
  2. Isolates of Aggregatibacter (formerly Actinobacillus) should be separated from other species of Haemophilus – antimicrobial treatment may be more prolonged. Most Haemophilus species grow more rapidly than Aggregatibacter and can be differentiated by their growth characteristics and colony morphology on enriched media.

Full critique (PDF)

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