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Objective@#To investigate the distribution of fimA and kgp genotypes as well as the common genotype combination of Porphyromonas gingivalis (Pg) in infected root canals of primary apical periodontitis for virulent isolates screening in future.@*Methods@#Thirty-four samples harboring Pg were selected from infected root canals of primary apical periodontitis from patients of the Department of Endodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from June 2013 to September 2015. FimA type-specific primers were used to amplify the samples, revealing the distribution of various fimA genotypes. The genotypes of kgp were obtained by using Mse Ⅰ restriction endonuclease. The prevalence of each genotype and common genotype combinations were then calculated. Pearson's chi-squared test was performed to analyze the correlation between genotype combinations and clinical symptoms and major signs of apical periodontitis. In addition, the bioflim architectures between Pg isolates with different fimA and kgp genotype combinations were observed compared using confocal laser scanning microscope.@*Results@#Among the 34 Pg-positive samples, fimA Ⅱ was the most prevalent genotype [47% (16/34)] followed by fimA Ⅰ [26% (9/34)], while fimA Ⅴ was detected in only one sample. The prevalence of kgp Ⅰ [56% (19/34)] was slightly higher than that of kgp Ⅱ [44% (15/34)]. Both fimA Ⅱ+kgp Ⅰ and fimAⅡ+kgp Ⅱ were the most prevalent genotype combinations [24% (8/34) each]. No significant correlation was found between specific genotype combination and such major clinical manifestations as gingival swelling and sinus tract of dental origin (P>0.05). Three Pg isolates with different genotype combinations were acquired. Isolate A (fimAⅠ+kgpⅠ) formed densest biofilm, while the biofilm of isolate C (fimAⅤ+kgp Ⅰ) was much looser. The biofilm feature of isolate B (fimAⅢ+kgp Ⅱ) fell in between A and C.@*Conclusions@#Pg with fimA Ⅱ was most frequently detected in infected root canals of primary apical periodontitis. The prevalence of Pg with kgp Ⅰ was slightly higher than that with kgp Ⅱ, and fimAⅡ+kgp Ⅰ as well as fimA Ⅱ+kgp Ⅱ were the commonest genotype combinations. According to the comparison of Pg biofilms formed by clinical isolates, it might be possible that different genotype combinations may lead to distinct biofilm architectures.
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Objective To investigate the effect of fimH gene on type 1 fimbriae adhesion of uropathogenic Escherichia coli (UPEC) and the gene variations between type 1 fimbriae adhesion positive and negative bacteria.Methods A total of 171 UPEC strains (not catheter associated) were collected from the Second Hospital of Tianjin Medical University,Tianjin First Center Hospital,and Tianjin Children's Hospital during January 2012 and January 2013.fimH gene was detected by PCR technique,and type 1 fimbriae adhesion was detected by yeast agglutination test.RT-PCR was used to exterminate gene transcript factor impacting on adhesion.Chi-square and Yates' chi-squared tests were performed to comparefimH gene sequences between the adhesion positive and negative bacteria.Results Among 171 UPEC strains,142 (83％) werefimH gene positive,and type 1 fimbriae was expressed in 98 strains (57％).All adhesion positive strains carriedfimH gene.Among 44 strains with positivefimH gene and negative adhesion RT-PCR revealed thatfimH gene did not transcript in 8 strains (18％).The sequencing results showed that gene mutation on the 51 st amino acid site was more prevalent in the adhesion positive group compared with the negative group (x2 =6.64,P =0.010).In adhesion,mutations on the 190th and 219th amino acid sites were observed in 6 strains and 7 strains of negative group,respectively; while not observed in the adhesion positive group (x2 =4.69 and 5.87,P ＜ 0.05).Negative adhesion in other 23 strains was not attributed to single nucleotide polymorphism.Conclusion Adhesion function of type 1 fimbriae mignt be affected by mutation and deletion offimH gene.Three key site mutations may also affect the adhesion function of type 1 fimbriae.Besides fimH gene,there may be other genes that can affect the adhesion function of type 1 fimbriae.
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Objectives To analyze the characteristics of antigenic genes of clinical Bordetella pertussis strains recently isolated by analyzing the sequence of pertussis toxin S1 subunit(ptxS1) , pertactin (Prn) , fimbriae 2 (Fim2) and fimbriae 3 (Fim3 ) genes of four clinical isolates. Methods The 4 clinical isolates were collected in 2002 in Shijiazhuang of Hebei province. Four strains were isolated from pertussis patient's nasopharyngeal aspirate. ptxS1, Prn, Fim2 and Fim3 genes of these strains were amplified and sequenced. The sequences of those genes were compared with those of the isolates in GenBank and the isoaltes used in the production of pertussis vaccine in China. Results The results of the gene sequencing showed the four clinical isolates belonged to ptxS1 A type, which were different from those in vaccine strains. In addition, three Prn and three Fim'3 variants were observed in the four clinical isolates. Sequence analysis showed that the nucleotide sequence and deduced amino acid sequence of those strains had more than 99% identity with those in vaccine strains. The phylogenetic trees of those genes also showed these strains had a higher level of similarity with other Bordetella pertussis strains. Conclusion The four clinical isolates are different from vaccine strains in four antigenic genes, which laid a foundation for further studies on pertussis epidemiology,quality control and development of pertussis vaccine in China.