青春期龈炎龈下菌斑中牙龈卟啉单胞菌kgp基因型的研究

目的 研究青春期龈炎龈下菌斑中牙龈卟啉单胞菌（P.gingivalis）的特异kgp基因型，评估其与疾病严重程度之间的关系。方法检查并记录青春期龈炎组与牙龈健康组各36例的牙周临床指数，收集龈下菌斑样本，提取染色体DNA，采用聚合酶链反应（PCR）方法扩增编码牙龈蛋白酶K（KGP）催化域的序列片段。PCR产物用限制性内切酶Mse I消化。结果 P.gingivalis有毒株W83表现为kgp-A型，而无毒株ATCC33277表现为kgp-B型。所有P.gingivalis阳性个体的龈下菌斑中只检测到一种kgp基因型。kgp-A型在青春期龈炎组P．gingivalis阳性个体中的检出率为79．0％，在牙龈健康组为22．2％，两组kgp基因型的检出率差异有统计学意义（P=0．028）；青春期龈炎组有P.gingivalis定植的个体中，牙周临床指数与kgp的基因型无相关关系（P〉0．05）。结论青春期龈炎个体定植的Pgingivalis的kgp基因型多与有毒株P.gingivalis W83的表现相同，有必要监测kgp-A型阳性的个体，因其个体发展为牙周疾病的危险度可能会增高。

kgp genotypes of Porphyromonas gingivalis in subgingival plaque in puberty gingivitis

Objective To assess the prevalence of specific kgp genotypes in puberty gingivitis and investigate their possible association with disease severity. Methods Subgingival plaque samples were collected from 72 pubertal children aged from 14 to 17 years, which were divided into two groups, gingivitis group and healthy (control) group. Clinical parameters were recorded beforehand. PCR technique was used to amplify the region encoding the catalytic domain of gingipain K(KGP). The PCR products were digested with restriction enzymes Mse I . Results The kgp-A genotype was digested in fragments of 102 bp, 288 bp and 402 bp, and kgp-B genotype was unrestricted with 792 bp. Virulent strain P. gingivalis W83 was manifested by kgp-A genotype while a virulent strain P. gingivalis ATCC 33277 was manifested by kgp-B genotype. All P. gingivalis positive subjects were subgingivally colonized by only one kgp genotype. The prevalence of kgp-A genotype in puberty gingivitis group and gingival healthy group was 79. 0% and 22. 2% respectively. The distribution differences of genotypes between the two groups were statistically different ( P = 0. 028). There was no statistically significant difference in the clinical parameters between pubertal subjects harboring P. gingivalis of kgp-A genotype and kgp-B genotype (P > 0. 05 ). Conclusions Most subjects with puberty gingivitis were harbored by the same kgp genotype as that of virulent strain P. gingivalisW83. It may be necessary to continue to monitor individuals who are positive for P. gingivalis of kgp-A genotype since their risk of developing periodontal diseases may be increased in the future.