O2056: Not Just a chunk: Mitral and aortic Valve Infective Endocarditis caused by Abiotrophia Defectiva

Introduction: Abiotrophia defectiva is a rare species leading to infective endocarditis (IE) with a poor prognosis. We describe a previously healthy patient with mitral and aortic valve infective endocarditis caused by A. defectiva.

Case Description: 5-year-old female with poor dentition but otherwise previously healthy who prior to admission to the pediatric Intensive care unit had a 1 week history of fever associated with cough for 1 month. She was seen by her Pediatrcian and was clinically diagnosed with murine typhus and prescribed doxycycline. The physician obtained a blood culture that was then reported as gram positive cocci. The mother was called, and the patient was brought to a local emergency department where she underwent further workup.
Chest x-ray was normal. CRP was elevated at 5.2 mg/dL, and a multiplex respiratory virus panel PCR was negative. A repeat blood culture was obtained. The patient received 1 dose of ceftriaxone. The repeat blood culture also grew gram positive cocci despite being on doxycycline for 5 days. Abiotrophia Defectiva was subsequently identified from both positive cultures. During the admission, the patient was afebrile. Infectious Disease was consulted and recommended continuation of ceftriaxone and doxycycline and ultimately recommended obtaining an echocardiogram for persistent positive blood culture. Echocardiogram was performed which demonstrated large vegetations in the mitral valve and aortic valces. This prompted transfer to our facility.
Echocardiogram revealed a large elongated mitral leaflet mobile vegetation measuring 12-15 mm in length and suggestion of a perforation in the anterior leaflet. There was also a large size mobile vegetation 18 x 10 mm attached to the aortic valve.
The patient was taken to the operative room (OR) by cardiovascular surgery. The finding in OR where aortic valve endocarditis, mitral valve endocarditis, and ascending aortic infection with mycotic aneurysm and contained aortic rupture. The surgeon performed aortic valve replacement, resection of mycotic aneurysm of the ascending aorta, resection of vegetation from mitral valve and mitral valve repair, with augmentation of the ascending aorta with good result. The patient was discharged after 17 days.

Discussion: IE is a rare finding in children with previously unknown heart disease. Most cases are caused by S.aureus and Streptococcus.virdans. Abiothrophia species is an extremely rare cause of IE. It has a high risk of embolic complication and valvular dysfunction that requires surgical intervention. Even patients with early appropriate antibiotic therapy and rapid achievement of bacteriological clearance remain at high risk for embolic and immune mediated complications and irreversible valvular damage.

Conclusion: Abiotrophia defectiva is an organism that is difficult to isolate, has serious complications and when it causes infective endocarditis it could require aggressive management with heart surgery and prolonged course of antibiotics therapy. It requires a high index of suspicion and multidisciplinary care.