Transmission and Establishment of Streptococcus mutans in an animal experimental system.

变形链球菌被认为是人类和实验动物龋齿中最重要的病原体。几项研究表明，大多数人，无论是否患有龋齿，都携带变形链球菌。而变形链球菌在乳牙出牙前未在口腔中检出。根据从一位母亲和她的孩子身上分离出的变形链球菌的血清学和细菌学相似性，这种变形链球菌感染似乎是家族内传播，特别是来自母亲的感染。本研究的目的是探讨大坝接种量对实验动物凋落物传播、龋齿发生率和变形链球菌建立的影响。利用在口腔内携带不同数量变形链球菌的SPF级雌性大鼠使其怀孕，观察变形链球菌从母鼠到产仔的传播情况。变形链球菌MT8148R和6715均未从10日龄和15日龄的窝产仔中检出，但在20日龄窝产仔中检出。断奶仔猪下颌骨中发现的变形链球菌数量与断奶仔猪下颌骨中发现的变形链球菌数量呈正相关。枯落物龋病发生率和严重程度与枯落物变异链球菌水平呈显著正相关。在SD大鼠和ICR小鼠中研究了接种量和感染攻毒对变形链球菌形成的影响。用不同接种量的变形链球菌感染动物1次或10次。与1次攻毒相比，10次攻毒能显著增强变形链球菌在大鼠或小鼠体内的建立。当给动物喂食蔗糖时，变形链球菌的建立增强了。

S. mutans has been considered to be most significant pathogen in dental caries of humans and experimentalanimals. Several studies indicated that most people, with or without dental caries, harbor S. mutans. However, S. mutans was not detected in the oral cavity before the eruption of primary teeth. This infection with S. mutans seemed to be of intrafamilial transmission, especially from mother, based on serological and bacteriological similarity of S. mutans isolated from one mother and her children. The purpose of the present study was to investigate the influence of inoculum size in dam to litter transmission, incidence of dental caries and establishment of S. mutans in experimental animals.SPF female rats, which had harbored various number of S. mutans in their oral cavities, were made pregnant, and the transmission of S. mutans from dam to litter was examined. S. mutans MT8148R or 6715 was not recovered from the mandibles of 10 or 15-day old litter in any of the groups, however, both strains were recovered in 20-days old litter. There were positive correlations between the number of S. mutans recovered from the mandibles of litter and those of dam at weaning. Furthermore, positive correlations were shown between the occurrences and severity of caries of litter with S. mutans level of dam. The influence of inoculum size and infectious challenges on the establishment of S. mutans were examined in SD rats and ICR mice. The animals were infected with various inoculum sizes of S. mutans either once or 10 times. Infection of S. mutans with 10 challenges enhanced the establishment of S. mutans markedly in rats or mice, compared with that of one infection. The establishment of S. mutans was enhanced when the animals were fed with sucrose diet.