EMPYEMA NECESSITATIS AS A COMPLICATION OF DIABETIC FOOT INFECTION

Abstract

SESSION TITLE: Chest Infections 2 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: We report a case of empyema necessitatis associated with diabetic foot infection secondary to Staphylococcus simulans, a commensal organism uncommonly associated with invasive infection. CASE PRESENTATION: A 58-year-old Caucasian man with a history of tobacco abuse and uncontrolled type 2 diabetes mellitus with associated neuropathy presented to a hospital emergency department three weeks after stepping on a tack. He developed a local infection, including cellulitis and myositis, which worsened until he decided to seek medical care. During this time, he had also noticed the development of a right-sided anterior chest wall mass. Exam and initial labs were significant for signs of sepsis and a fluctuant soft tissue mass at the right costochondral junction. Broad-spectrum IV antibiotics were started. Chest radiographs demonstrated a large right-sided pleural effusion, and an echocardiogram was negative for vegetations. Thoracentesis fluid studies indicated an exudative effusion with the presence of Gram-positive cocci eventually identified as a methicillin-resistant strain of Staphylococcus simulans. CT imaging of the chest demonstrated extension of the empyema through the mediastinum to the anterior right chest wall (Figure 1). A pleural drain was placed and intrapleural thrombolytics were administered. There was significant improvement on chest radiographs, and the patient was discharged from the hospital. Follow-up imaging after six weeks of outpatient broad-spectrum intravenous antibiotics showed resolution of the empyema, including the mediastinal and chest wall components (Figure 2). DISCUSSION: Empyema necessitatis, a complication of pleural empyema in which the infection invades the chest wall to create a soft tissue infection and/or abscess, is an uncommon complication of pleural infection.1 The most common causes are Mycobacterium tuberculosis and Actinomyces spp.1 In this case, the only identified organism was Staphylococcus simulans, a coagulase-negative commensal organism found in normal skin flora that is occasionally recognized as the likely culprit of skin and soft tissue infections and can be associated with significant antibiotic resistance.2 The most likely etiology of this empyema was hematogenous spread from his diabetic foot infection. Despite extension through the mediastinum to the distant anterior chest wall, local management of the empyema with chest tube drainage and intrapleural thrombolytics, as well as broad-spectrum IV antibiotics, successfully resolved this infection. CONCLUSIONS: Management of empyema necessitatis involves drainage and antimicrobial drugs and can be effective at resolving infection even at sites of distant invasion. Culture data is extremely important to guiding therapy and suspicion for Mycobacterium tuberculosis infection should remain high, especially in patients with risk factors. Reference #1: Freeman AF, Ben-Ami T, Shulman ST. Streptococcus pneumoniae empyema necessitatis. Pediatr Infect Dis J. 2004; 23(2): 177-9. Reference #2: Shields BE, Tschetter AJ, Wanat KA. Staphylococcus simulans: An emerging cutaneous pathogen. JAAD Case Rep. 2016; 2(6): 428-9. DISCLOSURES: no disclosure on file for Gregory Bobulsky; No relevant relationships by Joe Chiles, source=Web Response No relevant relationships by James Lamb, source=Web Response No relevant relationships by Ellen Liu, source=Web Response