Case Presentation:
A 37-year-old woman with significant history of intravenous substance abuse, six-year-old mechanical mitral valve replaced for mitral regurgitation and non-adherence to medications presented with shortness of breath and fever (103 F). She was hypotensive (84/64mmHg) and tachycardic (130/minutes). She was intubated and mechanically ventilated for acute respiratory failure. Lab results were remarkable for acute kidney injury, elevated BNP (1900 pg/mL), elevated troponin (0.142 ng/mL), thrombocytopenia (70,000 /ml), Hyponatremia (121 mmol/L), lactic acidosis (4.9 mmol/L), INR 1.7, elevated fibrin degradation products (20 uG/ml). Transesophageal echocardiogram revealed mixed thrombus and vegetation (4x2x3 cubic centimeter) adherent to the prosthetic mitral valve causing flow limitation and severely elevated mean gradient of 10.9 mmHg. Blood culture grew Achromobacter xylosoxidans. She underwent an emergent redo mitral valve replacement with 27-millimeter bioprosthetic valve and removal of large infected vegetation. Post procedure she suffered multiple cerebral infarcts resulting in significant neurological deficit even requiring intubation for airway protection. She was not anticoagulated for potential life threatening intracranial bleeding. She had significant clinical recovery and warfarin was started two weeks later. She was treated with intravenous Meropenem for six weeks resulting in uneventful recovery.
Upon revisiting the history, she confirmed the use of intravenous cocaine mixed with stored and tap water. Last injection was two weeks prior to the presentation.
Discussion: Achromobacter xylosoxidans, a motile, gram-negative bacillus, is an opportunistic and environmentally resistant organism that typically inhabits aqueous environments. This pathogen may cause meningitis, pneumonia, peritonitis and urinary tract infections in patients with cystic fibrosis and in immunocompromised hosts. Bacteremia from A. xylosoxidans is uncommon and endocarditis is even rare. This rare pathogen probably entered the bloodstream from injecting substances mixed with contaminated water. There are only thirteen case reports of A. xylosoxidans endocarditis since this organism was first isolated in 1971. A. xylosoxidans bacteremia has a mortality rate of between 15 and 48%. With timely actions including emergent valve replacement and multidisciplinary team approach she survived the complications including multi-organ failure and septic cerebral emboli. Decision-making on anticoagulation is challenging in these special circumstances. She is the sixth survivor out of the fourteen cases reported in the literature.
Conclusions: We report a unique complicated case of prosthetic mitral valve infective endocarditis caused by Achromobacter xylosoxidans in an intravenous drug user who survived the complications through timely surgical and medical management. Our experience resurfaces the importance of a through history including substance use, method of use and cutting agent used to form an inclusive differential diagnosis. Stroke complicating infective endocarditis poses a therapeutic dilemma, particularly in patients with prosthetic valves.