1. Introduction Mycotic aneurysm of thoracic aorta is a rare condition. This even more rare in children. We are reporting a case of mycotic aneurysm with community-acquired methicilin-resistant staphylococcus aureus (MRSA) in a healthy aldoscent male. He was successfully operated and send home with out any long term complications identified at 6 months follow up. Mycotic Aortic Aneurysm with Community- Acquired MRSA in a Healthy Teenager Durga P. Naidu, MD; Duraisamy Balaguru, MD University of Texas Health Science Center, Houston Texas Discussion Case Presentation A 15-year-old, previously healthy Hispanic male, presented to Emergency Room (ER) for sharp chest pain located in left upper chest, radiating to upper back. Admitted to feeling general malaise for 2-3 weeks prior. Chest X-ray (Figure 1A) and electrocardiogram were normal. Ibuprofen was prescribed and discharge. Presented twice on consecutive days to the ER, with fever, nausea and vomiting on the third visit. Small erythematous spot was noted in left palm and a cold sore in lower lip. Past medical history: Surgical repair of sports-related anterior cruciate ligament tear in right knee at age 13 yrs. Involvement in motor vehicle accident at age 3 yrs, without any injuries. Hospitalized. Urine and blood cultures were sent and Vancomycin, Rifampicin and Acyclovir were started. Endocarditis was suspected. Echocardiogram showed normal cardiac anatomy and trivial pericardial effusion. On 4 th hospital day, Chest X-ray 4-days after hospitalization (Figure 1B) showed widening of superior mediastinum. CT chest was performed (Figure 2) which showed paraaortic abscess with 4 cm saccular aneurysm of the distal aortic arch and upper thoracic aorta. Small pericardial effusion was present. Mild splenomegaly. Conclusions 1)Chest pain in children is mostly non-cardiac in origin. When it is associated with systemic features such as fever, malaise, nausea and vomiting, serious infectious causes have to be considered. 2)Careful follow-up of chest X-ray with specific attention to superior mediastinal shadow lead to timely diagnosis of this condition and avoid mortality. High mortality associated with aortitis and mycotic aneurysm formation is associated with diagnosis after extensive spread and aortic rupture. 3)Community-acquired MRSA in a previously-healthy child without any predisposing cardiac or aortic abnormality is rare. To our knowledge, only one other patient has been reported. 4)Value of Bactrim prophylaxis against MRSA is unclear. References 1.Lobe TE, Richardson CJ, Boulden TF, Swischuk LE, Hayden CK, Oldham KT: Mycotic thromboaneurysmal disease of the abdominal aorta in preterm infants and its management. J Pediatr Surg. 1992 Aug;27(8):1054-1059. 2. Aykan AÇ, Yıldız M, Özkan M: Infective endocarditis, thoraacic aortitis and mycotic aneurysm formation complicating balloon angioplasty of aortic coarctation. Cardiol Young. 2013 Feb;23(1):138-140. 3.Sirin G, Yilmaz O, Demirsoy E, Alan S, Soybir N, Sönmez B: Mycotic ascending aortic pseudoaneurysm at aortic cannulation site. Asian Cardiovasc Thorac Ann. 2009 Aug;17(4):417-418 4. Barth H, Moosdorf R, Bauer J, Schranz D, Akintürk H: Mycotic pseudoaneurysm of the aorta in children. Pediatr Cardiol. 2000 May-Jun;21(3):263-266. 5.Patel S, Maves R, Barrozo CP, et al. Mycotic pseudoaneurysm and purulent pericarditis attributable to MRSA. Mil Med. 2006;171:784-7/ Texas Pediatric Society Electronic Poster Contest Management Blood culture: MRSA Viral PCRs: Negative ESR: 80 mm/hr, High-Sensitive CRP: 60.7, RPR & HIV: negative. 1)Antibiotics – Vancomycin and Rifampicin were continued. Acyclovir was stopped. 2)Emergency surgery: Resection of aneurysm, Hemashield® graft repair of thoracic aorta and left subclavian artery and live coverage of graft using left latissmus dorsi muscle flap. Biopsy: showed presence of aortic wall in the specimen (aneurysm). Peri-aortic adipose tissue had hemorrhage. Cultures of aortic tissue grew MRSA. 3)Antibiotics were given for 8 weeks. 4)Repeat surgery for recurrence of aneurysm. Healed periaortic tissue was noted. Grafts were replaced along with replacement of ascending aorta. 5)Discharged home after 3 months on oral Bactrim (to be given life-long as prophylaxis against MRSA). 6)Doing well at 6 month follow-up. No recurrence of aneurysm. 1)Mycotic aortic aneurysm is extremely rare in children. 1 In both children and adults, there is usually a predisposing factor for myoctic aneurysms such as umbilical arterial catheter in neonates, infective endocarditis, coarctation repair 1,2, or open heart surgery especially for coronary artery bypass. 3,4 Most of these are described in adults. 2)Mycotic aneurysms have a high mortality secondary to aortic rupture and extension of infection to surrounding structures, myocardium, lung and pericardium. Early recognition from careful evaluation of Chest X-ray and prompt further imaging with CT angiogram, lead to early recognition and treatment in our patient. 3)Methicillin-senstive Staphylococcus aureus is commonly- identified pathogen. MRSA aortitis occurring in a previously-healthy individual has been reported only once (a 20-yr old male) and this was community-acquired MRSA. We chose to provide life-long prophylaxis according to advice from our infectious disease specialists. Value of Bactrim prophylaxis for MRSA remains unclear.