Bacteria have been used in food processing and have thus been ingested, live or dead, throughout human history. The safety of lactic and acetic acid bacteria has been confirmed over the years (5). However, in recent years, lactic acid bacteria belonging to the genera Lactobacillus, Leuconostoc, Pediococcus, or Bifidobacterium have been isolated from a variety of clinical samples, generally from patients with diabetes, cancer, or immunosuppression (6). As lactic acid bacteria are part of the normal human flora, their clinical relevance is often difficult to establish. In contrast, acetic acid bacteria have never been isolated from human flora; recently, the pathogenicity of an unknown bacterium that probably belonged to acetic acid bacteria, Granulobacter bethesdensis, was found in a patient with lymphadenitis