Lapirattanakul J, Nakano K, Nomura R, Hamada S, Nakagawa I, Ooshima T
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan.
Caries Res. 2008;42(6):466-74. doi: 10.1159/000170588. Epub 2008 Nov 7.
A new reliable genotyping method, multilocus sequence typing (MLST), was used to evaluate vertical transmission of the cariogenic pathogen Streptococcus mutans. A total of 136 S. mutans strains were isolated from saliva samples of 20 Japanese mother-child pairs, including 5 girls and 5 boys with primary dentition, and 5 girls and 5 boys with mixed dentition. The nucleotide sequences of 8 partial housekeeping genes, aroE, murI, gltA, glnA, glk, tkt, lepC, and gyrA, were analyzed and a similarity for all of those sequences between strains from a mother-child pair was regarded as indicating transmission, which was shown in 70% of the pairs. Interestingly, the rate of transmitted strains from mothers was significantly higher in the girls (90%) than in the boys (p = 0.001). Furthermore, the S. mutans sequence type (ST) with the highest distribution percentage in each maternal saliva sample was found to be transferred to their children. In addition, variations in two large conjugative-transfer associated regions, TnSmu1 and TnSmu2, were determined and compared with the STs defined by MLST. No variations in those two regions shown by PCR patterns were present in any of the strains isolated from the same families with the same STs, though isolates of some STs from different families showed distinct patterns for TnSmu2. Our results indicate that mothers are the main source for transmission of S. mutans to their children, while the present MLST method was also shown to be useful for investigating bacterial transmission.
一种新的可靠基因分型方法，多位点序列分型（MLST），被用于评估致龋病原体变形链球菌的垂直传播。从20对日本母婴的唾液样本中总共分离出136株变形链球菌，其中包括5名乳牙期女童、5名乳牙期男童、5名混合牙列期女童和5名混合牙列期男童。分析了8个管家基因aroE、murI、gltA、glnA、glk、tkt、lepC和gyrA的部分核苷酸序列，母婴对中菌株间所有这些序列的相似性被视为传播的证据，70%的母婴对呈现出这种情况。有趣的是，母亲传播给女童的菌株比例（90%）显著高于男童（p = 0.001）。此外，发现每个母亲唾液样本中分布百分比最高的变形链球菌序列类型（ST）会传递给其子女。另外，确定了两个大的接合转移相关区域TnSmu1和TnSmu2的变异，并与MLST定义的STs进行比较。来自同一家庭且具有相同STs的所有分离菌株中，PCR图谱显示这两个区域均无变异，不过来自不同家庭的一些STs分离株在TnSmu2上呈现出不同的图谱。我们的结果表明，母亲是变形链球菌向子女传播的主要来源，同时也表明目前的MLST方法对于研究细菌传播是有用的。
