Persistent bacteremia secondary to delayed identification of Lactobacillus in the setting of mitral valve endocarditis

INTRODUCTION: Lactobacillus species causing infective endocarditis is rare. Most reported cases arise from the oral ingestion of Lactobacillus via dairy or nutritional supplements in patients with congenital valve disease or replacement. We present a case of native valve bacterial endocarditis caused by Lactobacillus arising from dental abscesses. Additionally, there was an error in identification of the Lactobacillus as Corynebacterium, which led to inadequate treatment. PRESENTATION OF CASE: A 51-year-old male presented to an outside clinic with several weeks of subjective fevers and malaise. The provider obtained two sets of blood cultures. Both grew Gram-positive bacilli identified as Corynebacterium. Once hospitalized he persistently had positive blood cultures despite treatment with vancomycin and gentamicin. The specimens were sent to a reference lab. The cultures were confirmed to be Lactobacillus zeae resistant to vancomycin and gentamicin. Once he was started on appropriate therapy his blood cultures showed no further growth of bacteria. The infected teeth were removed as it was felt they were the source of the bacteremia. DISCUSSION: This case presents two interesting topics in one encounter. First, Lactobacillus is not a common culprit in endocarditis. Secondly, the incorrect identification of the gram-positive bacilli bacteria led to prolonged bacteremia in our patient. CONCLUSION: The patient was evaluated by cardiothoracic surgery at our facility and it was determined that he would likely need a mitral valve replacement versus repair. The decision was made to treat the patient with six weeks Penicillin-VK prior to the operation. He is currently completing his antibiotic therapy.