Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (487 page)

   Culture: Isolation of
B. dermatitidis
in culture provides definitive diagnosis of blastomycosis. Cultures of sputum, BAL aspirate, or infected tissue should be positive in most patients with active infection.

   Serology: Specific antibody detection has played a minor role in diagnosis of blastomycosis because of poor S/S. Sensitivity is reported approximately 90% and specificity approximately 80%.

   Routine laboratory: WBC and ESR are increased. Mild normochromic anemia is present; serum globulin may be slightly increased and/or serum ALP may be increased with bone lesions.

CANDIDIASIS

   Definition

   Candidiasis describes disease caused by any of several species within the fungal genus
Candida
.
Candida
species are globally distributed yeast, and those that cause infection form a part of the human endogenous flora, as well as the normal flora of other warm-blooded animals.
Candida
spp. are common inhabitants of the GI tract but may also be found on other mucosal surfaces, including the oral and genital tracts, and skin surfaces, including under the fingernails and toenails and intertriginous areas. Disease may occur when an individual’s local host defense mechanisms or systemic immunity is compromised. The incidence of invasive candidiasis has increased in the recent decades as a result of increasing use of broad-spectrum antibacterial agents and the emergence of AIDS and other immunocompromising conditions.

   
Candida albicans
is the most common cause of candidiasis. This species causes most infections of the genital, oral, and cutaneous sites. Candidiasis can also be caused by a number of other
Candida
species, most frequently:
Candida glabrata
,
Candida krusei
,
Candida lusitaniae
,
Candida parapsilosis
, and
Candida tropicalis
.
Candida dubliniensis
is a recently identified species that may mimic
C. albicans
in commonly used identification algorithms.

   Although several organism factors contribute to the ability of
Candida
species to cause infection, the most important factor is the status of the host’s immunity. Most infections are endogenous, usually caused by organisms from the individual’s GI flora. Most infections of deep tissues result from hematogenous spread from a primary site of infection. Disease processes that result in the breakdown of the integrity of the gut mucosa or skin surface are predisposing factors for hematogenous spread.

   Who Should Be Suspected?

   Mucosal and cutaneous candidiasis may occur in normal hosts with minor predisposing conditions, like recent antibiotic therapy. However, more serious conditions should be considered (e.g., HIV infection, DM).

   Genital (see discussion of vaginitis and vaginosis in Chapter
8
, Gynecologic and Obstetric Disorders).

   Oropharyngeal: “Thrush” is a common infection in healthy infants after antibiotic exposure but also occurs in patients with defects in cell-mediated immunity, like AIDS. In addition to recent antibiotic treatment, risk is increased by chemotherapy or head and neck radiation. Patients with dentures are also at increased risk. Oropharyngeal candidiasis usually presents with characteristic white plaques on the tongue, buccal mucosa, palate, or posterior oropharynx. Patients may be asymptomatic. Some patients complain of odynophagia or painful stomatitis, frequently seen in patients with dentures.