Lactobacillus species are facultative gram-positive, catalase-negative anaerobic bacilli that are part of the normal bacterial flora of the human gastrointestinal mucosa. They are rarely considered a pathogen but have been reported to cause bacteremia with or without endocarditis among other infections including vertebral osteomyelitis, liver or pelvic abscesses, meningitis, and pneumonia. They can cause disease in patients who are immunocompetent and immunocompromised. Recommended treatment of choice for severe infections due to Lactobacillus species endocarditis is high-dose penicillin in combination with an aminoglycoside.