Study of the distribution of Megasphaera micronuciformis in oral cavities of the Japanese by species-specific polymerase chain reaction (PCR) assay

Megasphaera micronuciformis is an anaerobic microbe isolated from humans. However, since the microbe is strictly anaerobic, its cultivation requires complicated facilities, making detection costly. For rapid, inexpensive detection and identification of M. micronuciformis in the clinical setting, a new technique is necessary. This study aimed to develop a species-specific PCR primer set for the detection of M. micronuciformis. A ribosomal DNA-specific PCR primer Mm2F was designed for M. micronuciformis. Analytical specificity data showed that the PCR primer set Mm2F/Mega-X produced amplicons from M. micronuciformis but not from the other species tested, including 4 Megasphaera species and representative related species. Of the 52 oral samples from Japanese subjects evaluated in our study, 71% were positive for M. micronuciformis, suggesting the likelihood that M. micronuciformis is widely distributed in the oral cavity of the Japanese population.    Key words: Megasphaera micronuciformis, specific polymerase chain reaction (PCR), Mm2F, oral bacteria.