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Legionella Pneumonia With Diffuse Macular Purpuric Rash and Negative Urine Test: A Diagnostic Dilemma FREE TO VIEW

Prashanth Thalanayar, MD; Shavitri Mahendiran, MD; Jonhan Ho, MD; Fernando Holguin, MD
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University of Pittsburgh Medical Center, Mckeesport, PA

Chest. 2014;145(3_MeetingAbstracts):119A. doi:10.1378/chest.1836677
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SESSION TITLE: Infectious Disease Case Report Posters I

SESSION TYPE: Case Report Poster

PRESENTED ON: Sunday, March 23, 2014 at 01:15 PM - 02:15 PM

INTRODUCTION: Legionella pneumophilia is the most common cause of legionellosis and is one of the organisms causing atypical pneumonia. This case report describes a case of Legionella pneumonia with unique clinical presentations and variations in diagnostic work-up.

CASE PRESENTATION: A 44-year-old male presented with a one week history of cough, fever, myalgia and a thigh rash. Shortly after admission he developed respiratory distress, was intubated and admitted to the medical ICU. CT chest revealed right middle and lower lobe pneumonia. Leukopenia(WBC 1.6) and thrombocytopenia(platelets 94000) were noted. He was started on broad spectrum antibiotics- vancomycin, ciprofloxacin, flagyl, and doxycycline. 24 hours later, the rash became more confluent, with dark necrotic-appearing areas. Blood, urine, and sputum cultures were negative. Legionella urinary antigen was reported negative. The initial serum antibody titer for legionella serogroup 1 was positive at 1:64, and subsequently 1:1024. Antibiotics were adjusted to include moxifloxacin. A biopsy from his right thigh revealed partial fibrin thrombi in superficial vessels as wells as mid-dermal vessels and fibrinoid degeneration of the vessel wall. Subsequent work-up revealed a diagnosis of Disseminated Intravascular Coagulation(DIC) most likely from underlying infection. Thereafter, the diffuse rash improved and the leucopenia and thrombocytopenia resolved. He was extubated later and was discharged home few weeks after having good recovery.

DISCUSSION: The disadvantage of using the urine Legionella antigen is that it only detects the most common type causing pneumonia, serogroup 1. Urine antigen testing has a 26% false negative rate. A four-fold or higher increase in the serum antibody titer is required to help establish the diagnosis. The diagnosis of Legionellosis cannot be based on the urine antigen tests and/or serological studies alone. The above case also presents an extensive maculopapular rash associated with severe Legionella infection diagnosed as 'purpura fulminans'. According to MEDLINE search, two cases of diffuse maculopapular rash have been reported. The pathogenesis of skin involvement is unclear. It may be due to a toxin released by the organism or related to an immune response of the host to the organism.

CONCLUSIONS: A false negative urine Legionella antigen test is not uncommon. Therefore, in the face of strong clinical suspicion, empirical therapy covering Legionella should be used due to increased mortality seen with delay in initiation of appropriate therapy. Cutaneous involvement with Legionellosis is uncommon and may present similar to purpura fulminans.

Reference #1: Shimada T, Noguchi Y, Jackson J et al . “Systematic Review and Metaanalysis: Urinary Antigen Tests for Legionellosis.” Chest. Dec. 2009; 136(6): 1576-1585

Reference #2: Calza L, Briganti E, Casolari S, Manfredi R, Chiodo F, Zauli T. Legionnaires’ disease associated with macular rash: two cases. Acta dermatovenereologica. 2005; 85(4): 342-4.

DISCLOSURE: The following authors have nothing to disclose: Prashanth Thalanayar, Shavitri Mahendiran, Jonhan Ho, Fernando Holguin

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