Endocarditis Caused by <i>Lactobacillus plantarum</i>

Abstract

Lactobacilli are considered nonpathogenic members of the human bacterial flora, and only eight serious infections have previously been described. This is the first documented episode of Lactobacillus plantarum endocarditis in the United States. The biochemical and growth characteristics and pleomorphic form on Gram stain were consistent with those of Erysipelothrix or Lactobacillus. Identification was made by growth of the organism on tomato-juice agar, lack of motility in gelatin at 22 °C and 37 °C, and failure to agglutinate with commercial E. insidiosa antiserum. The infection in a previously healthy 44-year-old woman had its source in the oral cavity and followed a dental procedure. Despite in-vitro sensitivity to 1 U/ml of penicillin, response to 24 × 106 U/day was inadequate. Rapid improvement and complete cure was achieved with 48 × 106 U/day. Lactobacilli isolated from patients with severe infections thus cannot be dismissed as contaminants.