Bacteroides levii-Like Organisms Isolated from Clinical Specimens

Bacteroides levii is an anaerobic, pigmented, gram-negative rod originally isolated from the bovine rumen. B. levii-like organisms (BLLO) have been isolated occasionally from human sources such as the vagina and from patients with chronic otitis media. These organisms closely resemble Porphyromonas species biochemically as well as by metabolic fatty acid profiles and antibiotic disk identification patterns (susceptibility to vancomycin), and their taxonomic position warrants reassessment. Because BLLO weakly ferment glucose, lactose, and mannose (which is often difficult to demonstrate with use of prereduced anaerobically sterilized [PRAS] media), their identification in clinical laboratories has been problematic; they are often either misidentified as Porphyromonas species or pigmented Bacteroides or Prevotella species or else reported as unusual pigmented, gram-negative rods. The aim of this report is (1) to describe the isolation of BLLO from clinical specimens and the laboratory tests that are useful in identification and differentiation of these organisms and (2) to assess the information available regarding predisposing conditions and clinical presentation of the infections.