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THE GRAM STAINADVANCED INTERPRETATIONS
Richard (Tom) Thomson, Jr., Ph.D.Northwestern University Feinberg School
of MedicineEvanston Northwestern Healthcare
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REVIEW OF THE BASICS
• Procedural highlights– Select area of specimen– Prepare smear– Low and high power scanning– Quantitate cells and microorganisms– Interpret by specimen source– Slides for review
• Interpret bacterial morphologies– Minimum competency– Advanced competency
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EXTRA GRAM STAIN MORPHOLOGIESINDICATORS OF PATHOLOGY
• White blood cells (polymorphonuclear leukocytes)
• Alveolar macrophages• Squamous/columnar epithelial
cells• Elastin/collagen fibers• Curschmann’s spirals• Corpora amylacea
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EXTRA GRAM STAIN MORPHOLOGIESINDICATORS OF PATHOLOGY
• Cell necrosis • Intracellular bacteria/yeasts• “Antibiotic” treated bacteria• Crystals• Respiratory therapy• Other oddities
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GRAM STAIN: PATTERN RECOGNITION
• Respiratory tract– Pneumonia/bronchitis– Aspiration pneumonia– Cystic fibrosis– Chronic lung disease/COPD
• Urinary tract– UTI– Vesicocolonic fistual
• Meningitis
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GRAM STAIN: PATTERN RECOGNITION
• Abscess– Staphylococcal– Mixed aerobic/anaerobic– Streptococcus milleri/anginosis– Nocardia
• Toxemia– Streptococcal necortizing fasciitis– Clostridium gas gangrene
• Miscellaneous– BV (bacterial vaginosis)– Lemierre’s disease (jugular vein thrombosis)– Gonococcal urethritis– Crystalline joint disease
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AFTER ALL THIS TRAINING
• Can you identify the pathogen in the following case?– Newborn sepsis– Mother appears at hospital in labor
• no pre-natal care
– Peri-partum fever– Child delivered vaginally
• Blood and CSF specimens for stain/culture
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CONCLUSIONSMicrobiology Model
• Standardize Gram stain procedure• Minimum competency for laboratory personnel• Gram stain review procedure• Advanced interpretation
– Indicators of pathology– Pattern recognition (diseases)
• Use Gram stain results in culture work-up• Train physicians to use the Gram stain• Future?
– Provide images of diagnostic Gram stains (high resolution monitors)
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