Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1320 page)

   
Turnaround time:
4 weeks

   Special Collection and Transport Instructions

   Inoculate blood culture system according to the manufacturer’s recommendations. Alert the laboratory if infection due to
Malassezia furfur
is suspected. Special culture processing is needed for isolation of this lipophilic yeast. Transport to the laboratory at room temperature.

   Interpretation

   
Expected results:
No growth

   Most commonly isolated pathogens in positive cultures:

   Yeasts:
Candida albicans
, nonalbicans
Candida
species, and
Cryptococcus neoformans
. (
Candida
and other commonly isolated yeasts may be efficiently detected using routine blood cultures.)

   Dimorphic fungus:
Histoplasma capsulatum
.

   Mold:
Fusarium
and
Scedosporium
species.

   Limitation

   
Aspergillus
species are rarely isolated by blood culture even in the presence of acute systemic infection.

Suggested Reading

CLSI.
Principles and Procedures for Blood Cultures; Approved Guideline
. CLSI document M47-A. Wayne, PA: Clinical and Laboratory Standards Institute; 2007.

BLOOD CULTURE, MYCOBACTERIAL

   Definition and Use

   The mycobacterial blood culture is used for the detection of bloodstream infection due to
Mycobacterium
species. Mycobacteremia is most commonly seen in patients with AIDS, although it may occur in other congenital and acquired immunocompromising conditions, including patients taking chronic corticosteroid therapy, and malignancies. Growth of mycobacteria in culture requires the use of specialized, supplemented media with prolonged incubation time. Lysis of blood cells improves detection, by releasing phagocytized organisms, and is used in most methods (e.g., lysis–centrifugation methods).