What is the role of culture and susceptibility testing in the workup of pneumococcal infections?

Updated: Jun 08, 2020
  • Author: Eduardo Sanchez, MD; Chief Editor: John L Brusch, MD, FACP  more...
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Antimicrobial susceptibility testing should be performed on all isolates of S pneumoniae, regardless of the isolation site, because of the increasing prevalence of intermediately susceptible and resistant isolates. All isolates should be tested for susceptibility to penicillin and either cefotaxime or ceftriaxone. In addition, CSF isolates should be tested for susceptibility to vancomycin and meropenem. CSF isolates that are found to be nonsusceptible to penicillin should also be tested for susceptibility to rifampin.

Microbiology laboratories should follow established guidelines regarding inoculum size and media (Mueller-Hinton agar with sheep, horse, or lysed horse red blood cells). Isolates from patients with invasive disease should undergo testing with quantitative minimal inhibitory concentration (MIC) techniques (eg, broth microdilution, antibiotic gradient strips).

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