Penetrating Chest Injury Leading to Methicillin-Resistant Staphylococcus Aureus (MRSA) Bacter-Emia and Mycotic Abdominal Aortic Aneurysm in Immunocompromised Patient

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Conference Proceeding

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Publication Title

J Gen Intern Med


Learning Objective #1: Recognize that mycotic aneurysm is a term used to describe any localized dilation of an artery due to destruction of the vessel wall by infection. This aneurysm can result from the infection or a preexisting aneurysm that becomes infected. Learning Objective #2: Recognize that trauma, endocarditis and impaired immunity are common risk factors for infected aneurysms. CASE: A 52-year-old male with a PMHx of chronic lower back pain s/p laminectomy, presented with a 4 day history of right-sided flank pain, subjective fevers and chills. Additional symptoms included dysuria along with episodic suprapubic pain. Vitals were significant for episodic fever. Physical examination was significant for superficial skin abscesses. He did admit to a recent history of incarceration and reported that he was stabbed in the right upper chest which resulted in a pneumothorax. There was a high index of suspicion for pyelonephritis. UA showed findings consistent with UTI. Initial urine cultures and blood cultures came back positive for MRSA. Due to evidence of persistent bacteremia, IV dapto-mycin and ceftaroline was initiated. CT chest showed findings consistent with septic emboli in the lungs. Echocardiogram was obtained and subsequent transesophageal echocardiogram which were negative for vegetations. MRI was negative for spinal abscess. HIV-1 quantitative and total CD4+ T cell count were obtained and revealed values 102,587 and 11, respectively. At this time, the patient began complaining of acute abdominal pain and painful pulsatile abdominal mass was appreciated on physical exam. CT-abdomen revealed a 3.1x2.8x3.5 cm saccular mycotic aneurysm projecting off the right side of the abdominal aorta. The patient was treated with 6 weeks of daptomycin and placed on dapsone and azithromycin prophylaxis following completion of daptomycin. The patient underwent surgical repair of the aneurysm with a rifampin-soaked Dacron graft and right nephrectomy for an infarcted right kidney. IMPACT/DISCUSSION: This case highlights that pentrating chest injury in a immunocompromised host led to a MRSA bacteremia causing a mycotic aneurysm. The most commonly involved organisms in mycotic aneurysms include S. aureus, Streptococci and Salmonella. In our case, the patient's risk factors for an infected aneurysm were the stab wound which was a likely inoculation site for MRSA and impaired immunity (HIV+). Clinical findings are a painful, pulsatile mass in the abdomen. CT angiog-raphy is the diagnostic test of choice. Empiric antibiotics should include MRSA and gram negative coverage, while definitive treatment is surgical excision of the aneurysm and extensive debridement of infected tissues. Conclusion:-Trauma such as penetrating chest wall injury, endocarditis, and immunocompromised hosts are common risk factors for infected aneurysms-Clinical presentation can include a painful, pulsatile mass-The diagnosis of an infected aneurysm is based upon imaging of the aneurysm and infection is confirmed with blood cultures and/or cultures from aneurysm wall.





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