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Morphology and diagnostics of
superficial and invasive candidiasis. The pathologist's point of view.Wien
Med Wochenschr. 2007;157(19-20):522-5.
Adherence to the
epithelial surface and tissue invasion represent the major steps in the
pathogenesis of candida infection. Grossly, localized (superficial)
candidiasis shows well circumscribed white patches, whereas invasive
(systemic) candidiasis is characterized by abscess formation.
Polymorphonuclear neutrophil cells accompany filamentous and yeast forms of
Candida sp. in localized infection. Fungal abscesses demonstrate central
necrosis, surrounded by a dense suppurative infiltrate. A granulomatous
response may be observed. To identify the infectious agents, a combined
cytologic and histopathological approach is recommended.
Biological diagnosis of
systemic candidiasis: difficulties and future prospects.Pathol
Biol (Paris). 2007 Jun;55(5):262-72. Epub 2006 May 12.
The diagnosis of
systemic Candidiasis is difficult to establish and biologic diagnosis raises
problems. Blood culture which is the gold standard for the diagnosis of
systemic Candidiasis lacks sensitivity and usually takes several days to
become positive. Early diagnostic approach is imperative to avoid delays in
the initiation for treatment. Therefore, nonculture methods like test for
Candida antigen detection, metabolite detection or Candida DNA detection by
PCR are being developed for the laboratory diagnosis. Candida derived
metabolites and antigens detection lacks sensitivity. A new strategy
consisting of the combined detection of mannanemia and an antibody response
was developed. The combined detection has a high specificity and sensitivity
in the diagnosis of invasive candidiasis. The results of tests for the
detection of yeast DNA by PCR obtained recently are promising in terms of
sensitivity, specificity and identification of species of Candida.
Laboratory diagnosis of
invasive candidiasis.J
Microbiol. 2005 Feb;43 Spec No:65-84.
Invasive candidiasis is
associated with high morbidity and mortality. Clinical diagnosis is
complicated by a lack of specific clinical signs and symptoms of disease.
Laboratory diagnosis is also complex because circulating antibodies to
Candida species may occur in normal individuals as the result of commensal
colonization of mucosal surfaces thereby reducing the usefulness of antibody
detection for the diagnosis of this disease. In addition, Candida species
antigens are often rapidly cleared from the circulation so that antigen
detection tests often lack the desired level of sensitivity. Microbiological
confirmation is difficult because blood cultures can be negative in up to
50% of autopsy-proven cases of deep-seated candidiasis or may only become
positive late in the infection. Positive cultures from urine or mucosal
surfaces do not necessarily indicate invasive disease although can occur
during systemic infection. Furthermore, differences in the virulence and in
the susceptibility of the various Candida species to antifungal drugs make
identification to the species level important for clinical management. Newer
molecular biological tests have generated interest but are not yet
standardized or readily available in most clinical laboratory settings nor
have they been validated in large clinical trials. Laboratory surveillance
of at-risk patients could result in earlier initiation of antifungal therapy
if sensitive and specific diagnostic tests, which are also cost effective,
become available. This review will compare diagnostic tests currently in use
as well as those under development by describing their assets and
limitations for the diagnosis of invasive candidiasis. |
