In addition to cultures, which lab tests are performed in the workup of pneumococcal infection?

Updated: Jun 08, 2020
  • Author: Eduardo Sanchez, MD; Chief Editor: John L Brusch, MD, FACP  more...
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Other laboratory values that may be helpful in diagnosis and treatment include a complete blood cell (CBC) count and differential, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).

In children who do not produce sputum and in adults with a nonproductive cough, the diagnosis may be made based on urine antigen testing for S pneumoniae. As with urinary antigen testing for Legionella, antigenuria may not be present in early infection or in patients without bacteremia, but, if present, may persist after clinical resolution of infection. Evaluation of sputum via a combination of culture, Gram stain, and pneumococcal antigen was found to be the most useful way of achieving an etiologic diagnosis of CAP. Pneumococcal antigen detection in sputum has been shown to have high sensitivity (90%), even compared with urinary antigen detection essays, in early and mild CAP in pretreatment patients whose sputum specimens can be obtained. [55] The pneumococcal urinary antigen assay may augment the standard diagnostic methods of blood culture and sputum culture, as it provides rapid results. [3] It is unable to provide antimicrobial susceptibility data, so it does not supplant traditional culture methods.

The role of fiberoptic bronchoscopy is best established in the absence of adequate sputum for culture or when the patient is not responding to current therapy. [56]

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