Dr. Sinkoff presents the case of a middle aged gentleman who presented with confusion, hyponatremia and pneumonia ultimately diagnosed with legionella.
Teaching points:
1. Pneumonia classifications:
Community Acquired pneumonia
Health care associated pneumonia: within 90 days of hospitalization, visitation to hemodialysis, residence in long term facility
Hospital acquired pneumonia: >/= 48 hours after admission
Ventilator associated pneumonia: >/= 48 hours after intubation
2. Legionella makes up 2-15% of all community-acquired pneumonia cases that required hospitalization
Inhalation of aerosols containing legionella, microaspiration of contaminated water
Infection may occur without obvious source
Classically hotels, hospitals, cruise ships, office buildings
Can be severe in presentation - complicated by stupor, respiratory failure, multiorgan failure, diarrhea
Hyponatremia is a hint that a pneumonia might be legionella
Diagnosis is better made by urine antigen test (sensitivity of 68-81%, specificity of 98-99%). Urine antigen testing evaluates for serotype 1 infection, results can remain positive for prolonged periods after initial infection
Culture only has a sensitivity of 60-61% and has a >48 hour incubation period.
Treat with levofloxacin or azithromycin
3. How do we risk stratify patients with pneumonia?
CURB-65 scoring:
4. What is the best way to rule out a PE in a patient that presents with symptoms of dyspnea, tachycardia, and hypoxia?
PERC criteria: can be applied to a subset of patients at very low risk - these patients don't even require a D-dimer
---> In a recent meta-analysis, if the PERC were applied only 0.3% of PEs would have been missed, and 22% of D-dimer testing would have been avoided
---> If PERC is >0, D0dimer should be pursued
Wells Criteria for PE
Low pretest probability + negative D-Dimer: no imaging necessary
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