Laboratory Tests and Ancillaries
Lab exams are used to help identify the different Candida sp and susceptibility to antifungals. Species identification is recommended to be used as a guide for empirical management and for outbreak detection and surveillance. When utilizing direct microscopy, enhancing visualization by using optical brighteners or application of periodic acid-Schiff or Grocott’s methenamine silver stain on formalin-fixed, paraffin-embedded tissue samples is strongly recommended. Culture, in-situ identification techniques, and panfungal polymerase chain reaction (PCR) followed by sequencing should also be considered. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) or Clinical and Laboratory Standards Institute (CLSI) antifungal susceptibility testing is recommended in patients with mucocutaneous infections unresponsive to standard treatment. Chromogenic agars are recommended for the detection of mixed yeast infections. Additionally, PCR assays with peptide nucleic acid fluorescence in-situ hybridization (FISH) support is used to detect some Candida spp. Lastly, matrix-assisted laser desorption/ionization-time of flight (MADLI-TOF) mass spectrometry helps provide species-level identification.
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Cutaneous Candidiasis
Skin
Doing Gram stain or potassium hydroxide (KOH) mount may show Candida sp. Predominantly.
Paronychia and Onychomycosis
Doing Gram stain or KOH mount in paronychia and onychomycosis may also show Candida sp predominantly.
Please see Tinea Unguium disease management chart for further information.
Mucosal Candidiasis
Oropharyngeal (Thrush)
Gram stain or KOH preparation may show masses of hyphae, pseudohyphae, and yeast forms. It must be noted that culture is not specific because Candida grows easily from normal mouths. Lastly, there may be irregular esophageal mucosa on radiologic studies.
Esophageal
The definitive diagnostic for esophageal candidiasis is biopsy during endoscopy or by brushing. In appropriate clinical settings, endoscopic appearance of white patches that show masses of hyphae and pseudohyphae on scraping is enough evidence to initiate therapy. Additionally, confirmation of findings of direct endoscopic visualization is done using fungal culture and speciation. To avoid invasive procedures, empiric antifungal therapy may be given to an at-risk patient who presents with typical symptoms along with oral thrush.
Intra-abdominal
Intra-abdominal candidiasis may show single or multiple ulcerations containing Candida deep in ulcer beds on endoscopy. White plaques and thickening of mucosal folds in the duodenum and jejunum may also be seen.
Vulvovaginal
Vulvovaginal candidiasis is confirmed by the presence of blastosphere, yeast or hyphae in vaginal secretions and a normal pH (4-4.5) in a wet-mount preparation with the use of saline and 10% potassium hydroxide.
Please see Vaginitis: Trichomoniasis, Candidiasis, Bacterial Vaginosis disease management chart for further information.
Chronic Mucocutaneous Candidiasis
Diagnostics that can be done in mucocutaneous candidiasis include culture and biopsy of involved areas/organs, and KOH.
Imaging
A definitive diagnostic that can be done in esophageal candidiasis is non-contrast axial computed tomography (CT) scan. Additionally, Fluorine-18 fluorodeoxyglucose positron emission tomography/CT ([18F]-FDG PET/CT) may be used for the evaluation of deep-seated intra-abdominal candidiasis in immunocompromised patients.
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