CLINICAL LABORATORY DIAGNOSTICS OF PATHOLOGICAL PROCESSESS IN LUNGS

1. CLINICAL LABORATORY DIAGNOSTICS OF PATHOLOGICAL PROCESSESS IN LUNGS Marushchak Maria

2. Obtaining a sputum sample • Mouth should be free of foreign objects • Remove food, gum, or Tobacco • Remove dentures • Early morning specimen is best • Induce sputum if necessary • Nebulized hypertonic saline or distilled water • Chest percussion • Postural drainage • Cough into sterile specimen cup

3. Special Circumstances • Tuberculosis suspected • Sputum collected in negative pressure room • Early morning gastric aspirate • Bronchoscopy with bronchial lavage • Anaerobic culture specimen • Transtracheal aspiration • Thoracentesis • Direct lung puncture • Viral Culture Specimens • Patient gargles and expectorates with nutrient broth • Nasopharyngeal swab transported in viral medium

4. Preparation of Sputum for Lab • Fixation of sputum for cytology (prevents air drying) • Patient expectorates into jar of 70% Ethanol • Spread fresh sputum on slide and spray pap fixative • Culture specimen transport to lab • Sputum Gram Stain assesses sample for adequacy • Anaerobic cultures transported in air tight container • Transport to lab for immediate plating • Aerobic culture specimen • Bring to lab as quickly as possible • Refrigerate specimen if transport delayed • Consider washing specimen of oral flora • Rinse several times with saline • Discard supernatant (non-viscous Saliva) • Tuberculosis culture • May be stored at room temperature for up to 48 hour

5. Sputum Gross Exam

6. Estimate daily volume of Sputum • Small amounts • Lung Abscess • Pneumonia • Tuberculosis • Copious amounts (>200 cc/day) • Bronchiectasis • Bronchopleural Fistula

7. Sputum Color • Bloody Sputum (Hemoptysis) • Rusty Sputum (Prune-juice) • Pneumococcal Pneumonia • Purulent Sputum (yellow, green, dirty-gray) • Color alone does not distinguish bacterial infection

8. Sputum Turbidity • Frothy Sputum (air bubbles, Hemoglobin) • Pulmonary edema • Foamy, clear material • Saliva • Nasal secretions

9. Sputum Viscosity • Bloody Gelatinous Sputum (Currant-Jelly) • KlebsiellaPneumonia • Pneumococcal Pneumonia • Stringy Mucoid Sputum (may also appear frothy) • Follows Asthma exacerbation • Cloudy, mucoid Sputum • Chronic Bronchitis • Three layered appearance (stagnant, Purulent Sputum) • Bronchiectasis • Lung Abscess

10. Sputum with Feculent Odor • Anaerobic infection • Bronchiectasis

11. Sputum Microscopy

12. Assessing Sputum Sample Quality • Ideal Sputum Sample for Culture • Under 10 squamous epithelial cell per low power field • Many Neutrophils present (>5 per high power field) • Bronchial epithelial cells present • Alveolar Macrophages may be present • Inadequate Sputum Sample • Over 25 squamous epithelial cells/LPM

13. Sputum Sample Preparation • Pull strand or plug of Sputum onto slide • Consider buffered crystal violet to stain cells • Apply cover slip • View under oil immersion

14. Cytology Stains • No Stain • Blastomycosis • Cryptococcosis • Gram Stain • Gram Positive Bacteria • Candida • Tuberculosis (weakly Gram Positive) • Nocardia (weakly Gram Positive) • Direct Fluorescent Antibody Staining • Legionella • Wright stain or Giemsa Stain • Intracellular organisms

15. Special Staining Circumstances

16. Acid-fast Mycobacteria (Tuberculosis) • Ziehl-Neelsen Stain (Red against blue background) • Kinyoun stain • Less reliable than Ziehl-Neelsen stain • Results in quickly stained sample • Fluorochrome dyes (auramine, rhodamine) • Higher false positive rate than Ziehl-Neelsen stain • Assist greatly in identifying organisms

17. Fungal Organisms • PAS staining or Methenamine silver staining • Histoplasmosis • Coccidioidomycosis • Aspergillus • Mucor • KOH Preparation

18. Microscopic findings • Caseous masses • Dittrich's plugs • Curschmann's spirals (Asthma) • Charcot-Leyden Crystals (Asthma) • Bronchial casts • Concretions • Broncholith • Calcified particles as seen in Broncholithiasis • Lung Cancer cells • Central bronchus tumors • May require 4 samples to detect • Eosinophils (>5%): identified with Wright's Stain • Allergy • Asthma

19. Pneumonia • General • Lab Indications • Moderate or severe community acquired pneumonia • Patient with comorbid conditions • Efficacy of Labs • No value in non-severe community acquired pneumonia

20. Sputum Examination • Tests • Sputum Gram Stain • Sputum Culture • Efficacy of Sputum exam • Sputum has low diagnostic yield in CAP • Not recommended in community acquired pneumonia

21. Blood Culture • Indications • Not indicated unless severe disease • Recommended by ATS in hospitalized CAP • Efficacy • Low sensitivity: Positive in only 5-10% of cases • Does not predict severity or outcome

22. Specific Testing with reasonable efficacy • Chlamydia pneumonia • Rapid PCR (>30% Test Sensitivity) • Influenza • Rapid Influenza Test (Influenza DFA) • Legionella pneumophila • Rapid PCR of Sputum (80% Test Sensitivity) • Urinary antigen (>50% Test Sensitivity) • Mycoplasma pneumoniae • Rapid PCR of Sputum (>30% Test Sensitivity)

23. Chronic Bronchitis • Labs • Arterial Blood Gas (ABG) • Markedly reduced arterial pO2 • Elevated arterial pCO2 (40-50 mmHg) • Pulmonary Function Tests • Residual Volume increased • FEV1 decreased • FEV1/FVC decreased • FEF 25-75 (mid-flows) decreased • Diffusion capacity (DLCO) near normal

24. Bronchiectasis • Labs: Sputum • Sputum forms layers on standing • Top: Mucus • Middle: Clear fluid • Bottom: Pus • Sputum Culture not diagnostic (mixture of organisms) • Fungal Culture

25. Lung Abscess • Labs • Sputum examination • Microscopy • Gram Stain • Mycobacterial stains • Fungal stains • Sputum layers on standing • Sputum Cultures are usually not helpful • Complete Blood Count • Leukocytosis

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