Case 46

1. Presented by Ankit Rajgariah, MD and reviewed by Karen Carroll, MD

A middle-aged patient with a past medical history of hypertension and hyperlipidemia, presents to the emergency department with two days of weakness, fevers, chills, and poor appetite. Over the past few days, the patient had worsening shortness of breath, weakness, and became confused. Of note, the patient recently returned from a trip to a foreign country and was there for several weeks. During the time abroad, the patient was around construction sites and changed water tanks.

Upon presentation, the patient was profoundly hypoxic with SpO2 of 57%. The patient was emergently intubated and started on a ventilator. In addition, the patient was tachycardic, hypotensive with a blood pressure of 90/68, and febrile at 39.2 C. The patient's initial CBC showed a WBC of 17,510 with a neutrophil predominance (87.1% neutrophils, 7.5% lymphocytes, 4% monocytes). A complete metabolic panel was notable for decreased sodium, 129 meq/L, elevated creatinine, 2.4 mg/dL, and elevated liver enzymes, ALT 173 u/L and AST 164 u/L. In addition, the patient's troponin was increased to 0.12 ng/mL. Two sets of blood cultures, urine culture, sputum culture, and urinary antigen tests for Streptococcus pneumoniae and Legionella were ordered. The patient was started on antibiotics empirically and admitted to the ICU.

Question: What organism does the BinaxNow® Legionella urinary antigen detect?