DISSEMINATED PULMONARY HISTOPLASMOSIS IN IMMUNOCOMPETENT PATIENTS: A COMMON EPIDEMIOLOGICAL EXPOSURE IN CONSTRUCTION WORKERS

Abstract

SESSION TITLE: Chest Infections 4 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Most histoplasmosis infections in immunocompetent patients are asymptomatic and self-limited. The following are four immunocompetent patients with a common epidemiologic exposure--construction work---that presented with disseminated pulmonary histoplasmosis and acute respiratory failure. CASE PRESENTATION: The first three cases involved 19, 44 and 70-year-old males presenting with fevers, severe dyspnea and productive cough over 2 weeks after remodeling a same old apartment building. Diffuse crackles were heard on lung auscultation. Chest X-rays and CT chests showed bilateral diffuse lung nodules and alveolar opacities. Patients failed antibiotic therapy and was transferred from a local hospital due to worsening respiratory status. The 19-year-old patient was the first admitted to the ICU. Initially, patient was diagnosed with severe community acquired pneumonia and treated with vancomycin and piperacillin-tazobactam. However, given worsening conditions and history of recent construction work, acute pulmonary histoplasmosis was suspected. Patient was started on empiric amphotericin B and systemic corticosteroid. The 44 and 70-year-old patients were later transferred and started on same antifungal therapy given same exposure. Later, histoplasmosis was confirmed with positive bronchoalveolar lavage (BAL) cultures and urine/serum/BAL Histoplasma antigen. The last case was a 48-year-old male presenting with similar symptoms, physical exam, and chest x-ray and CT chest findings as above. Given his recent work remodeling an old building, patient was empirically started on itraconazole and systemic prednisone. Histoplasmosis was later confirmed with positive BAL/sputum cultures and urine/serum Histoplasma antigen. All four patients recovered with 12 weeks of antifungal therapy. DISCUSSION: Patients most likely developed disseminated pulmonary histoplasmosis due to high level of fungal inoculum from construction work in old buildings. Diagnosis of histoplasmosis is often challenging because (1) clinical presentation resembles bacterial or mycobacterial infections, or inflammatory conditions, (2) diagnosis is confirmed through isolation of the fungus in cultures which take several weeks or histopathology that is invasive. Detection of Histoplasma antigen or Histoplasma antibodies aids in diagnosis but also limited by long turnaround time, low sensitivity and cross reactivity with other mycosis. Misdiagnosis often leads to inappropriate therapy with unnecessary antibiotics or immunosuppressive agents and delay in appropriate antifungal therapy. CONCLUSIONS: It is important to recognize any epidemiologic exposure (construction work, traveling, hiking, farming) for histoplasmosis, promptly start a diagnostic work-up and have a low threshold to start empiric antifungal therapy. Also, workers with potential exposure to bat/bird droppings should be educated on use of N95 respirator as recommended by NIOSH. Reference #1: Benedict K, Mody RK. Epidemiology of Histoplasmosis Outbreaks, United States, 1938-2013. Emerg Infect Dis. 2016;22(3):370-8. Reference #2: Azar MM, Zhang X, Assi R, Hage C, Wheat LJ, Malinis MF. Clinical and epidemiological characterization of histoplasmosis cases in a nonendemic area, Connecticut, United States. Med Mycol. 2017. Reference #3: Wheat LJ, Azar MM, Bahr NC, Spec A, Relich RF, Hage C. Histoplasmosis. Infect Dis Clin North Am. 2016;30(1):207-27. DISCLOSURES: No relevant relationships by Swan Lee, source=Web Response No relevant relationships by Rolando Sanchez, source=Web Response