THE MYSTERY OF THE MIGHTY MEDIASTINAL MASS: WHEN STREPTOCOCCUS ANGINOSUS GOES ROGUE

Abstract

SESSION TITLE: Chest Infections 3 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Streptococcus anginosus group (SAG: S. anginosus, S. intermedius, S. constellatus) is a subgroup of viridans streptococci that can cause thoracic infections, which carry significant morbidity and mortality. As part of normal oral flora, they can cause empyema and lung abscesses from aspiration. Mediastinitis is a rare presentation and can occur as primary infection or from spread of neck infection. Risk factors include periodontal disease, alcoholism and respiratory tract surgical procedures. Since streptococci are normal oral flora, diagnosis requires isolation of organism from cultures of blood, pleural fluid, or a respiratory sample obtained invasively. CASE PRESENTATION: A 40 y.o. female with no significant PMH presented to the ER for worsening dry cough and night sweats for 3 months and high-grade fevers, dyspnea, chest tightness and right neck pain for 4 days. History was significant for cave exploration and teeth cleaning 3 months ago. Her father had diffuse large B-cell lymphoma.On examination, BP:134/79 mmHg, HR:128/min, Temperature:99.5 F, RR:18/min, O2 saturation:100%. Lungs clear to auscultation and no peripheral lymphadenopathy. WBC: 19,000 cu mm. CT Angio Chest showed a new 7 x 7.2 x 4.6 cm right upper mediastinal mass encasing innominate, vertebral, and common carotid arteries. CT Neck showed the mass extended into the right portion of the neck causing mass effect on the right internal jugular vein. CT-guided needle aspiration of the mass yielded 4cc of pus and normal flow-cytometry. During the procedure, she had a fever of 103. IV piperacillin-tazobactam and oral itraconazole were started. Blood cultures and mediastinal aspirate grew pan-sensitive SAG (S. constellatus). Quantiferon Gold, ACE level, antigens for histoplasma, blastomyces, coccidioides and aspergillus were normal. Right video assisted thoracoscopic surgery (VATS) was performed with drainage of a large purulent mass. Intra-operative cultures were negative but pleural biopsies grew SAG (S. constellatus). Her post-operative course was uneventful. DISCUSSION: While histoplasmosis and malignancy were considered given recent cave exploration and family history of lymphoma, it is important to keep SAG infection in mind when evaluating a patient with mediastinal mass, high fevers and history of dental procedures. CONCLUSIONS: We believe this is a rare and uniquely aggressive manifestation of SAG thoracic infection. Given potential for fatal complications from spread of mediastinal infection by crossing of tissue planes with encasement of great vessels and airways, timely intervention with thoracoscopy and appropriate intravenous antibiotics is critical in these high-risk patients to prevent poor outcomes. Bacteremia should prompt a search for other focal suppurative seeding, such as brain abscesses. Reference #1: Sunwoo, B. Y., & Miller, W. T. (2014). Streptococcus anginosus Infections Crossing Tissue Planes. https://doi.org/10.1378/chest.13-2791 DISCLOSURES: No relevant relationships by Mohamed Babiker-Mohamed, source=Web Response No relevant relationships by Manojna Nimmagadda, source=Web Response No relevant relationships by William Sanders, source=Web Response No relevant relationships by Nehan Sher, source=Web Response