Molds-Disk Diffusion Assay: Introduction, Principle, Methods, Clinical Significance, and Keynotes

Introduction The disk diffusion assay for molds is a standardized antifungal susceptibility testing (AFST) method that evaluates the sensitivity or resistance of filamentous fungi to antifungal agents. While primarily standardized for yeasts (e.g., CLSI M44-A2), disk diffusion has also been adapted for molds, particularly Aspergillus …

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Yeasts-Broth Microdilution Testing (EUCAST): Introduction, Principle, Clinical Significance, and Keynotes

Yeasts-Broth Microdilution Testing (EUCAST) Introduction, Principle, Clinical Significance, and Keynotes

Introduction Fungal infections caused by yeasts, particularly Candida and Cryptococcus species, represent a significant clinical challenge in immunocompromised and critically ill patients. Antifungal susceptibility testing (AFST) is crucial for guiding therapy, particularly in cases of treatment failure or the emergence of resistance. The broth microdilution …

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Fungal Identification by Artificial Intelligence (AI): Introduction, Working Mechanisms, Clinical Significance, and Keynotes

Yeast and mold growth on SDA agar

Introduction Fungal infections represent a growing concern in both immunocompromised and immunocompetent individuals. Conventional identification methods, including culture, microscopy, and biochemical testing, often require several days and may lack sensitivity or specificity for certain opportunistic fungi. Molecular techniques such as PCR and sequencing have improved …

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Leucine Crystals: Introduction, Identification Features, and Clinical Significance

Leucine crystal in urine microscopy at a magnification of 1600X

Introduction Leucine crystals are rare urinary findings that typically appear in patients with severe liver disease, such as advanced cirrhosis, severe hepatitis, or metabolic disorders like maple syrup urine disease. They form in acidic urine and indicate a disturbance in amino acid metabolism. Identification Features …

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Sulfonamide Crystals: Introduction, Identification Features, and Clinical Significance

Sulfonamide (sulfadiazine) crystals in urine sediment microscopy

Introduction Sulfonamide crystals are drug-induced urinary crystals that appear in patients receiving sulfonamide (sulfa) therapy, particularly when urine is acidic, concentrated, or dehydrated. They occur due to precipitation of unmetabolized sulfonamide compounds in urine, especially older drugs like sulfadiazine, which are less soluble in acidic …

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Urate Crystals: Introduction, Identification Features, and Clinical Significance

Uriate crystals in urinary sediment microscopic examination at a magnification of 1600X

Introduction Urate crystals, also referred to as uric acid crystals, are metabolic by-products of purine metabolism found in urine. They are frequently observed during urine microscopy, especially in patients with altered pH, dehydration, or metabolic disorders. Their presence can be physiological in concentrated urine or …

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Ascitic Fluid Microscopy: Introduction, Principle, Test Requirements, Procedure, Finding, Clinical Significance, and Keynotes

Collected Ascitic Fluid

Introduction Ascitic fluid microscopy is a laboratory diagnostic method used to examine peritoneal (ascitic) fluid obtained via paracentesis. It helps in identifying cells, microorganisms, and crystals that provide clues about underlying causes such as infection, malignancy, liver disease, or systemic disorders. Principle The principle of …

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Pleural Fluid Microscopy: Introduction, Principle, Test Requirements, Procedure, Finding, Clinical Significance, and Keynotes

Collected Pleural Fluid-

Introduction Pleural fluid is the liquid collected from the pleural space between the lung and chest wall. Microscopic examination of pleural fluid plays a key role in identifying the underlying cause of pleural effusion. It helps distinguish between transudates and exudates, detect infectious organisms, malignant …

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