Today our residents reviewed a case of an elderly gentleman presenting after 1 week of symptoms that includes fevers, chills, SOB, malaise, nausea, vomiting, and diarrhea. He reported recent travel to Las Vegas and stayed at a hotel with his wife and other friends. Then ~8 days ago his wife started to have symptoms and the next day his symptoms started.
Patient was found to be febrile, hypoxic, and tachycardic on admission. Labs showed a hyponatremia, AGMA, a significant AKI, leukocytosis, and elevated LFTs. We then reviewed the CXR and discussed a differential for our patient’s presentation. Based on the clinical presentation we discussed additional labs/studies to order. These included ESR, CRP, COVID PCR, RPNA panel, hepatitis panel, Legionella Urine Antigen, and Cocci serologies.
Patient was found to have a positive Legionella urine antigen, confirming diagnosis of Legionnaires disease. We then discussed clinical factors that should raise clinical suspicion for Legionella and patient risk factors associated with infections. We reviewed IDSA recommendations for testing all patients with moderate or severe pneumonia given potential severity of symptoms if not treated early. Lastly we discussed different ways to test for legionella, noting that Urine Antigen is the fasted and most common, BUT it only tests for one serogroup of 1 species. Given that serogroup is responsible for >80% of cases worldwide it is still a good initial test, but it does not rule out Legionella if clinical suspicion is still high!
- Clinical factors that raise suspicion for Legionella- GI symptoms, hyponatremia, elevated LFTs, CRP levels >100 mg/L
- Recommended to test for legionella in all patients with moderate or severe CAP (hospitalized)
- Test with PCR or Urine Antigen (remember urine antigen only tests for L. pneumophilia serogroup 1)
- Cases of Legionella have been increasing steadily over the past two decades