Direct Microscopy-KOH Smear: Introduction, Uses, and Keynotes

Introduction Direct microscopic examination is one of the most rapid and inexpensive diagnostic methods for detecting fungal elements in clinical specimens. Potassium hydroxide (KOH) smear is a routine technique in mycology that helps visualize fungal structures such as hyphae, yeast cells, and sclerotic bodies directly …

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Aspergillus-Antigen Testing:Introduction, Principle, Clinical Significance, and Keynotes

Aspergillus-Antigen Testing-Introduction, Principle, Clinical Significance, and Keynotes

Introduction Aspergillus species, particularly Aspergillus fumigatus, are major causes of invasive aspergillosis (IA), especially in immunocompromised patients, such as those with hematological malignancies, transplant recipients, or those with prolonged neutropenia. Diagnosis of IA is often challenging because clinical symptoms and radiological findings are nonspecific. Aspergillus …

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β-D-Glucan: Introduction, Principle, Clinical Significance, and Keynotes

Introduction β-D-Glucan (BDG) is a polysaccharide component of the fungal cell wall, widely present in species such as Candida, Aspergillus, Fusarium, and Pneumocystis jirovecii. Since it is released into the bloodstream during invasive fungal infections (IFIs), detection of BDG has become a valuable non-culture-based diagnostic …

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Blood Culture–Positive Yeasts: Introduction, Common molds, Comparison, and Keynotes

Gram-positive budding yeast-like cells, oval to elongated, arranged singly, in pairs, and in short pseudohyphae-like forms in Gram staining of culture microscopy at a magnification of 4000X

Introduction Unlike molds, yeasts are the most commonly recovered fungi in blood cultures. Candidemia is among the leading causes of bloodstream infections in immunocompromised and critically ill patients. Yeasts such as Candida, Cryptococcus, and Trichosporon are responsible for significant morbidity and mortality. Blood culture positivity …

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Blood Culture–Positive Molds: Introduction, Common molds, Comparison, and Keynotes

Blood Culture–Positive Molds

Introduction Blood cultures are the cornerstone for diagnosing fungemia, but while yeasts (Candida spp.) are frequently detected, molds are rarely recovered in blood culture systems. This is because most molds (Aspergillus, Mucorales) cause tissue-invasive disease without sustained fungemia. However, certain molds such as Fusarium spp. …

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Yeasts-Colorimetric Antifungal Susceptibility Testing: Introduction, Principle, Clinical Significance, and Keynotes

Yeasts-Colorimetric Antifungal Susceptibility Testing-Introduction, Principle, Clinical Significance, and Keynotes

Introduction Yeasts, especially Candida and Cryptococcus species, are frequent causes of opportunistic infections in immunocompromised patients. Determining their antifungal susceptibility is crucial for guiding effective therapy. While broth microdilution methods (CLSI/EUCAST) serve as reference standards, they are labor-intensive and time-consuming. Colorimetric antifungal susceptibility testing systems …

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Fungal Identification by PCR-Sequencing (Sanger): Introduction, Principle, Clinical Significance, and Keynotes

Pure culture of Candida

Introduction Accurate identification of fungi is critical for clinical, environmental, and epidemiological purposes. Traditional culture and morphology-based methods are time-consuming and may misidentify cryptic or closely related species. PCR amplification followed by Sanger sequencing of conserved genetic loci (e.g., ITS, 18S rRNA, 28S rRNA, β-tubulin, …

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Yeast Identification by MALDI-TOF (VITEK): Introduction, Principle, Clinical Significance, and Keynotes

Yeast Identification by MALDI-TOF (VITEK): Introduction, Principle, Clinical Significance, and Keynotes

Introduction Yeasts, especially Candida species, are among the most important causes of opportunistic fungal infections in humans. Accurate and rapid identification is crucial for guiding antifungal therapy and improving patient outcomes. Traditional phenotypic methods are time-consuming and often misidentify cryptic species. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight …

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