Bronchoalveolar lavage (BAL) Gram stain: Introduction, Report-Interpretation, Clinical Significance, and Keynotes

Gram negative cocobacilli in Gram staining of BAL and pus cells

Introduction Bronchoalveolar lavage (BAL) is a diagnostic procedure used to collect specimens from the lower respiratory tract, particularly from the alveolar spaces. It is performed by instilling sterile saline into a segment of the lung via a bronchoscope and then aspirating it back. Gram staining …

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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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Throat Swab Gram stain: Introduction, Report-Interpretation, Clinical Significance, and Keynotes

Gram positive and Gram negative bacteria in throat swab Gram stain photomicrograph at a magnification of 4000X

Introduction A throat swab Gram stain is a rapid, initial diagnostic test performed on specimens collected from the oropharynx or tonsillar region. It helps to identify bacterial flora, pathogens, and inflammatory response. While culture and molecular methods provide definitive diagnosis, Gram staining offers early guidance …

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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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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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