Pediatric Nocardiosis Workup

Updated: Oct 04, 2013
  • Author: Nicholas John Bennett, MBBCh, PhD, MA(Cantab), FAAP; Chief Editor: Russell W Steele, MD  more...
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Workup

Laboratory Studies

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  • Gram staining is indicated in nocardiosis.
    • Directly examine clinical materials (eg, sputum, bronchoalveolar lavage, cerebral spinal fluid, pus) by Gram stains and acid-fast stains (modified Ziehl-Neelsen stains). Delicately branched, weakly gram-positive, variably acid-fast bacilli with tendency to fragment are indicative of Nocardia.
    • Use methenamine-silver stains for demonstrating the organisms in tissue specimens.
    • Inoculate clinical material, including blood specimens, on brain-heart infusion media or Sabouraud agar without antibiotics. N asteroides and N braziliensis are obligate aerobes, thermophilic, and slow growing. Colonies take 1-2 weeks to develop and are usually waxy then chalky in appearance.
  • Serological diagnosis is not readily available.
  • Cultures typically grow within 3-5 days on blood or chocolate agar, but cultures from normally sterile sites should be maintained for 3 weeks in a liquid medium.
  • Case reports of positive testing for beta-D-glucan with nocardial infections have been published, [8, 9] but it isn't always clear whether concomitant infection with a fungus or Pneumocystis was ruled out. In some cases PCP or a candidal infection were discovered shortly after the Nocardia diagnosis, both of which would produce elevated beta-D-glucan levels.
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Imaging Studies

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  • Generalized infections
    • Chest radiographic findings vary and include fluffy infiltrates, scattered nodules, and confluent lobar infiltrates progressing to complete consolidation and cavitation.
    • Chest CT scanning may be necessary to visualize the extent of disease and to rule out empyema.
    • CT scanning with contrast or MRI may be necessary to visualize cerebral abscesses.
  • Disseminated nocardiosis
    • Perform CT scanning with contrast or MRI to rule out cerebral abscesses. Because of the high incidence of spread to the brain, all patients with pulmonary nocardiosis should have a neuroimaging study, even in the absence of CNS symptoms. Lesions should show ring-enhancement with contrast and fluid-attenuated inversion recovery (FLAIR). Early lesions, or those present during treatment with steroids, may not enhance and may mimic infarction.
    • Use 2-dimensional echocardiography to rule out vegetations.
    • Perform abdominal and/or pelvic sonography and CT scanning to rule out intra-abdominal, hepatic, splenic, or renal abscesses.
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Procedures

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  • A bronchoalveolar lavage is recommended in immunocompromised individuals in whom nocardiosis is suspected because mortality can exceed 50% without rapid diagnosis and treatment.
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