BACKGROUND: Infective endocarditis associated with bacterial infections has a 20% mortality rate despite many scientific advances. The most common pathogens causing infective endocarditis are Staphylococcus aureus (S. aureus), Streptococcus viridans (S. viridans) and Enterococcus. The ability of these pathogens to become resistant, has allowed an upward trend in the development of new cases. The goal of this study was to increase awareness of unusual causes of infective endocarditis to help avoid mortality in infected patients.

CASE REPORT: A 63-year-old Caucasian male presented to the emergency department with onset of a new murmur and atrial fibrillation. Based on diagnostic findings, mitral valve repair was suggested. Prior to his scheduled surgery, the patient exhibited physical signs of infection, despite negative blood cultures and negative labs. The patient underwent cardiac surgery, and shortly thereafter, the tissue culture yielded positive results for vancomycin-resistant Enterococcus (VRE) and Lactobacillus.

CONCLUSIONS: Thorough laboratory studies had negative serial (×3) blood cultures with no aerobic or anaerobic growth, no acid fast bacilli on smear, and no mycological growth. Tissue culture of a mitral valve leaflet, in a subculture broth, grew VRE species and Lactobacillus species. Good clinical suspicion, empirical treatment, and a successful tissue culture led to finding and treatment of an unusual case of infective endocarditis.

Keywords: Endocarditis, Lactobacillus, Mitral Valve Prolapse, Vancomycin Resistance