Streptococcus anginosus infection in oral cancer and its infection route.

To elucidate a possible involvement of Streptococcus anginosus in oral cancer, we assessed the frequency of S. anginosus infection in oral cancer tissues, and investigated its infection route. The tissue specimens were obtained from 46 oral cancer and three precancerous leukoplakia subjects. Frequency of S. anginosus infection was assessed by a species-specific polymerase chain reaction (PCR) assay. The genotype of the clinical isolates taken from cancer tissue and dental plaque samples was analyzed using pulsed-field gel electrophoresis (PFGE). S. anginosus DNA was frequently detected in squamous cell carcinoma (19/42), but not in other types of cancer (lymphoma and rhabdomyosarcoma) or leukoplakia samples. A subject-based analysis revealed that S. anginosus was solely detected in dental plaque and not in saliva from all 19 S. anginosus-positive squamous cell carcinoma cases. Further, the genotype of S. anginosus isolated from cancer tissue was identical to that from dental plaque of the same patients. Infection of S. anginosus could occur frequently in oral squamous cell carcinoma and that dental plaque could be a dominant reservoir of the S. anginosus. [ABSTRACT FROM AUTHOR]