Characterization of Solobacterium moorei Strains from Subjects with Halitosis

Objectives: Solobacterium moorei is a gram-positive anaerobic bacillus originally isolated from human feces. Studies of clinical samples taken from human subjects with and without halitosis analyzed by bacterial culture and direct amplification of nucleic acids indicate that Solobacterium moorei is significantly associated with halitosis. This study examined the type strain and four clinical isolates of S. moorei. Methods: The type strain JCM10645 and clinical isolates SUNYAB H3-63, SUNYAB H6-109, SUNYAB H7-23, and SUNYAB H8-20 obtained from four different patients with halitosis were examined for restriction fragment length polymorphisms using double digests of HindIII / EcoRI and HindIII / BamHI probed with 16S rDNA; 16S rDNA sequence; enzymatic activity by semi-quantitative API-ZYM; susceptibility to 18 antibiotics by disc diffusion on solid media; susceptibility to seven commercially-available mouthwashes by serial dilution in liquid media; and, production of volatile sulfur compounds by culture on fastidious anaerobe agar. Results: Genome sequence analysis of 16s rDNA indicated ≥98% similarity for all 5 strains. RFLP analysis could differentiate strains except for SUNYAB H7-23 and SUNYAB H8-20 which were identical by both RFLP and 16S rDNA sequence. Detectable enzyme activities included acid phosphatase, beta-galactosidase, alpha-glucosidase, esterase, lipase, leucine arylamidase, naphtol phosphohydrolase and N-acetyl-beta-glucosamidase. S. moorei strains were highly sensitive to most of the antibiotics tested but no strain was susceptible to gentamycin, nalidixic acid, or rifampin and only strain SUNYAB H8-20 was susceptible to kanamycin. Oral rinses containing chlorhexidine gluconate and cetylpyridinium chloride were most effective against the S. moorei isolates. All isolates produced volatile sulfur compounds as shown by culture on fastidious anaerobe agar. Conclusions: S. moorei strains like other bacterial species associated with oral halitosis produce volatile sulfur compounds. There is genetic and phenotypic heterogeneity among S. moorei strains isolated from human subjects with oral halitosis. The study was supported by NIH Grant DE07034.