During hospitalization, he continued to have persistently elevated white blood cell count, with no clear explanation on workup. He was needing aggressive diuresis for his clinical picture of cardiogenic shock and associated fluid overload. Multiple sets of blood cultures remained negative after more than 72 hours of incubation. Computed tomography of abdomen and pelvis scan revealed no abscess or foci of infection.

He was started on empiric intravenous ceftriaxone given his recent history of K. oxytoca septicemia. Echocardiograms via both transthoracic and transesophageal approaches were pursued which showed preserved left ventricular ejection fraction however was concerning for native aortic valve endocarditis with severely thickened aortic valve and a pseudoaneurysm of aortic root.

Cardiothoracic surgery was consulted given findings of valvular endocarditis with symptoms and signs of left ventricular failure. He subsequently underwent surgical debridement of aortic annulus and left ventricular outflow tract with aortic valve replacement. Intraoperatively, chronic vegetation at the base of the right coronary cusp with fibrosis of the left ventricular outflow tract was found. Debrided valve tissue was sent for bacterial, acid-fast bacilli (AFB) test, fungal cultures and direct DNA sequencing by PCR. Gram stain and routine bacterial, mycobacterial and fungal cultures of the operative specimens were negative. However, K. oxytoca  specific DNA was detected on the ribosomal DNA amplification by polymerase chain reaction of diseased valve/tissue.

The patient clinically improved after a few days’ stay in the cardiac care unit post-surgery and was continued on intravenous ceftriaxone. He was able to be discharged home after eleven days of hospitalization and was continued on intravenous antibiotics via a peripherally inserted central catheter to complete a four-week course. On a post-hospital discharge visit to the cardiology clinic, he clinically improved and continued to participate in physical therapy sessions.