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Legionella
Aka: Legionella, Legionella pneumophila, Legionella pneumonia, Legionnaire's Disease, Legionellosis, Pontiac Fever- See Also
- Pathophysiology
- Aerobic, intracellular, Gram Negative Rod
- Virulent organism
- More severe disease than other Atypical Pneumonia
- Transmission
- Optimal conditions for growth
- Temperature: 89 to 113 F water
- Stagnant water
- Waterborne Illness
- Freshwater or moist soil near ponds
- Air conditioning
- Condensers
- Cooling towers
- Respiratory therapy equipment
- Showers or water faucets
- Whirlpools
- Aeorsolized mist (hot tubs, decorative fountains)
- Optimal conditions for growth
- Incubation
- Two to ten days
- Aerobic, intracellular, Gram Negative Rod
- Risk Factors
- Tobacco Smoking
- Chronic Renal Failure
- Malignancy
- Immunosuppression
- Diabetes Mellitus
- Chronic Liver Disease
- Exposure to recent plumbing work
- Overnight stay outside the home
- Presentations
- Symptoms
- Signs
- Severe respiratory distress
- Confusion
- Disorientation
- Complications
- Respiratory Failure (20-40% of cases)
- Extrapulmonary complications
- Radiology: Chest XRay
- Small Pleural Effusions
- Unilateral parenchymal infiltrates
- Round, fluffy opacities
- Spread contiguously to other lobes
- Progresses to dense consolidation
- Progresses to bilateral infiltrates
- Labs
- Complete Blood Count
- Erythrocyte Sedimentation Rate
- Elevated markedly
- Liver Function Tests increased
- Sputum Exam
- Fluorescent Antibody studies of Sputum
- Legionella can not be seen on Gram Stain
- Diagnosis
- Legionella urine Antigen testing
- High sensitivity and Specificity for serogroup 1
- Serogroup 1 (LP1) causes most U.S. cases (80%)
- Sputum Culture required to identify other serogroups
- Urine Antigen and Sputum Culture all cases
- References
- High sensitivity and Specificity for serogroup 1
- Concurrent Sputum and Blood Culture in all suspected cases (before antibiotics)
- Sputum Culture on special medium
- Legionella Serologies
- Legionella fourfold titer rise to >= 1:128 or
- Legionella titer >= 1:256
- Legionella urine Antigen testing
- Management (Antibiotic course for 21 days)
- Azithromycin IV
- Levofloxacin IV
- Trovafloxacin IV
- Erythromycin IV
- Add Rifampin in Immunocompromised or severe disease
- Course
- Response to antibiotics may not be seen for 4-5 days
- Up to 10-15% mortality in some studies
- References
- Gilbert (2001) Sanford Antimicrobial, p. 28
- Akbas (2001) Postgrad Med 109(5):135-47 [PubMed]
- File (1998) Infect Dis Clin North Am 12(3):569-92 [PubMed]
- Klein (1998) Semin Respir Infect 13(2):140-6 [PubMed]
- Perkins (2017) Am Fam Physician 95(9):554-60 [PubMed]
- Plouffe (2000) Clin Infect Dis 31:S35-9 [PubMed]
- Tan (1999) Can Respir J 6:15A-9A [PubMed]
- Waterer (2001) Am J Med 110(1):41-8 [PubMed]