L actobacilli are gram-positive, rod-shaped bacteria that are rarely infectious, and their presence as commensal organisms in the gastrointestinal tract is associated with protection against pathogens, stimulation of the immune system, and positive effects on colonic health and the host's nutrition. Nevertheless, lactobacilli have also been identified in some clinical reports as causal agents of dental caries, infectious endocarditis, urinary tract infections, and intra-abdominal, liver, and spleen abscesses. Endocarditis due to Lactobacillus is associated with impaired immunity, structural heart disease, recent surgery, prolonged antibiotic therapy, and severe comorbid conditions.2 Some clinical reports show a 30% mortality rate associated with endocarditis caused by lactobacilli.3 Probiotic agents that serve as entry vehicles for Lactobacillus have been identified as a relatively new risk factor in the genesis of these infections. 4 Case ReportA 48-year-old man with a history of paroxysmal supraventricular tachycardia (ablated in the past), mild aortic regurgitation, and the implantation (4 years earlier) of upper and lower dental bridges, presented at our emergency department. He reported exertional shortness of breath, increased lower-extremity edema, 3 months of intermittent fever ranging from 100.4 to 102.9 °F, and recent left-upper-quadrant abdominal pain.The patient was lethargic. His vital signs included a blood pressure of 112/43 mmHg, a heart rate of 113 beats/min, a respiratory rate of 20 breaths/min, and an oral temperature of 99 °F. His examination was notable for jugular venous distention (12 cm), a grade III/IV holosytolic murmur heard over the left lower sternal border, crackles in the lung bases bilaterally, splenomegaly, 3+ pitting edema bilaterally up to the knees, and scattered red macules anterior to the shins. His laboratory results indicated pancytopenia, acute renal failure, and hypoalbuminemia. His white blood cell count was 3.9 × 10 3 /µL, hemoglobin 7.1 g/dL, platelet count 114 × 10 3 /µL, serum creatinine 4.51 mg/dL, and albumin 2.3 g/dL. The urinalysis showed many bacteria, hyaline and granular casts, microscopic hematuria, and 50 white blood cells per highpower field. Blood cultures from 2 different venipuncture sites grew Lactobacillus acidophilus.A transthoracic echocardiogram revealed a left ventricular ejection fraction of 0.60 and a membranous ventricular septal defect with a mobile, echodense, vegetative mass 1.1 cm in diameter, moving between the left ventricular outflow tract and the right ventricle. Mild dilation of the aortic root was found, together with mild aortic regurgitation.Initial antibiotic treatment with empiric vancomycin and piperacillin/tazobactam was switched to penicillin on treatment day 4 for a 6-week course after species Case Reports