全托儿童口腔变形链球菌水平传播的初步研究

目的　通过对幼儿园全托儿童之间口腔变形链球菌水平传播的研究,为儿童龋病预防提供新的思路。方法　选择24名3~4岁全托儿童为研究对象,其中无龋组和有龋组各12名。采用无菌牙签采集牙面菌斑,厌氧培养48 h,根据变形链球菌的典型形态挑取单个菌落进行次代纯培养,经形态学和微量生化鉴定后将分离的菌株行AP-PCR扩增,对来自不同个体基因型相似的菌株再进行DNA指纹分析。结果　24名受检儿童中,变形链球菌检出率为66·7%,无龋组和有龋组检出率分别为58·3%和75·0%。经AP-PCR扩增,24名儿童口腔中检测出29个不同基因型的变形链球菌,其中携带2个以上基因型儿童占45·8%。经DNA指纹分析,有2种基因型在11名全托儿童口腔中有重复检出。结论　变形链球菌在全托儿童口腔中可能存在水平传播。

Study on the Horizontal Transmission of Oral Streptococcus mutans in Children

Objective To find out horizontal transmission of oral Streptococcus mutans(S.mutans) in nursery children through analyzing the similarity of S.mutans[WTBZ] genotypes.Methods The study group included 24 nursery children between 3 and 4 years of age.Dental plaque samples were collected with sterile toothpick and cultured on MSB plates for 48 h.Individual Streptococcus mutans group colonies representative of the colonial morphologies were subcultured on TPY plates. These strains were identified to species level biochemically.AP_PCR fingerprinting was preformed after identification.S.mutans isolates from different children with very similar fingerprinting profiles were examined by chromosomal DNA fingerprinting analysis.Results Streptococcus mutans group were isolated in oral cavities of 66.7% children,58.3% in caries_free and 75.0% in caries children.A total of 46 S.mutans isolates from 24 subjects were analyzed by AP_PCR,and 29 different amplitypes were identifyied,45.8% carried two genotypes.There were 2 genotypes of S.mutans isolated repeatedly among 12 nursery children.Conclusion The presence of matching genotypes of S.mutans among nursery children suggests horizontal transmission.