Fixed orthodontic treatment is conducive to dental plaque accumulation and gingival inflammation. In our study, after removal of orthodontic appliances, periodontal health improved, and the carriage and amount of subgingival P. gingivalis decreased. Nevertheless, the amount of subgingival P. gingivalis remained high for 6 months after appliance removal, and this finding might imply a potential risk to periodontal health in certain patients.

Subgingival plaque samples and root canal samples were collected from 2,839 marginal periodontitis (MP) patients and 21 apical periodontitis (AP) patients. Enterococcus species were identified by a series of phenotypic and genotypic tests. Antimicrobial susceptibility assays were performed by an agar disk diffusion test. Multilocus sequence typing (MLST), eBURST, and minimum spanning tree were used for enterococcal genetic clustering and population analysis. Enterococcus faecalis was recovered from 3.7% MP patients and 9.5% AP patients, and Enterococcus faecium was recovered from 0.04% MP patients. Enterococci were detected more often in older male patients. E. faecalis isolates of MP were found resistant to tetracycline (49.1%), erythromycin (8.5%), trimethoprim (2.8%), and gentamicin (1.9%), while one AP isolate was resistant to tetracycline. A total of 40 sequence types (STs) were resolved in 108 E. faecalis isolates. Comparison with E. faecalis international MLST database revealed that 27 STs were previously found, 13 STs were novel, and several major clonal complexes in the database were also found in MP isolates. The tetracycline-resistant isolates distributed mainly in the major clonal complexes and singletons, whereas the erythromycin-resistant isolates were more dispersed. Although the rate of occurrence of enterococci recovered in the MP and AP samples was low, 50% of these isolates are resistant to at least one antimicrobial agent, which is most often tetracycline. This implies that subgingival E. faecalis might represent a reservoir of resistance to tetracycline and erythromycin. The subgingival E. faecalis isolates show high genetic diversity but are grouped, in general, with the known isolates from the international database.

β-1, 4-Galactosyltransferase gene (B4GALT) family consists of seven members, which encode corresponding enzymes known as type II membrane-bound glycoproteins. These enzymes catalyze the biosynthesis of different glycoconjugates and saccharide structures, and have been recognized to be involved in various diseases. In this study, we sought to determine the expressional profiles of B4GALT family in four pairs of parental and chemoresistant human leukemia cell lines and in bone marrow mononuclear cells (BMMC) of leukemia patients with multidrug resistance (MDR). The results revealed that B4GALT1 and B4GALT5 were highly expressed in four MDR cells and patients, altered levels of B4GALT1 and B4GALT5 were responsible for changed drug-resistant phenotype of HL60 and HL60/adriamycin-resistant cells. Further data showed that manipulation of these two gene expression led to increased or decreased activity of hedgehog (Hh) signaling and proportionally mutative expression of p-glycoprotein (P-gp) and MDR-associated protein 1 (MRP1) that are both known to be related to MDR. Thus, we propose that B4GALT1 and B4GALT5, two members of B4GALT gene family, are involved in the development of MDR of human leukemia cells, probably by regulating the activity of Hh signaling and the expression of P-gp and MRP1.

Genetically heterogeneous yeasts were found in the oral cavities of marginal periodontitis patients and oral health subjects. Similar genetic clustering patterns were obtained from the yeasts of the two groups, with cluster V being most predominant. Yeasts of the marginal periodontitis group were more genetically diverse than yeasts of the oral health group, and some yeasts of the marginal periodontitis group exhibited unique genetic patterns. There was no clear association between yeast genetic clusters and oral sites in the two participant groups.

The present study aimed to identify and characterize plasmids in a national collection of oral Enterococcus faecalis (n = 106) isolated from patients with marginal periodontitis. Plasmid replicon typing was performed by multiplex-PCR and sequencing with specific primers for 18 rep-families and 1 unique sequence. Additional plasmid analysis by S1-PFGE was performed for comparison. Totally 120 plasmid replicon amplicons of seven rep-families were identified in 93 E. faecalis strains, e.g. rep9 (prototype pCF10), rep6 (prototype pS86), rep2 (prototype pRE25/pEF1), and rep8 (prototype pAM373). Rep9 was the most predominant rep-family being detected in 81 (76.4%) strains. Forty of these strains were tetracycline resistant and three were erythromycin resistant. Rep6 was the second predominant rep-family being detected in 22 (20.8%) strains. Rep2 was detected in eight (7.5%) strains. All rep2-positive strains were resistant to tetracycline and/or erythromycin and six of them contained Tn916/Tn1545 genes. The rep-positive E. faecalis exhibited divergence in multilocus sequence types (STs). There was a significant correlation between rep9 and ST21, while multiple rep-families appeared in ST40. Totally 145 plasmid bands were identified in 95 E. faecalis strains by S1-PFGE, 59 strains carrying one plasmid, 27 carrying two, five carrying three, three carrying four, and one strain carrying five plasmids. Plasmid sizes varied between 5–150 kbp. There was a significant correlation between the number of plasmids identified by PCR rep-typing and by S1-PFGE. The results indicate that the majority of E. faecalis of marginal periodontitis are likely to be a reservoir for diverse mobile genetic elements and associated antimicrobial resistance determinants.

The E. faecalis strains of chronic periodontitis exhibited weak biofilm formation ability at the early stage. Over 50% of the strains were resistant to tetracycline, and a few strains were highly resistant to erythromycin or gentamicin. E. faecalis cells in biofilm were hardly eradicated by most of the agents, even in high concentrations. Triclosan was effective in inhibiting E. faecalis growth in both biofilm and planktonic phase.

Yeasts can be members of the commensal flora in the healthy human mouth. They have also been found in periodontal pockets of patients with marginal periodontitis, but little is known about their distribution in other oral sites of such patients. The aim of the present study was to examine the distribution of genera, species and biotypes of yeasts in various sites of oral cavities of patients with chronic marginal periodontitis. Samples were taken from the periodontal pockets, buccal mucosa and palate of 70 marginal periodontitis patients and 45 healthy individuals. After cultivation yeast colonies were selected according to morphology and the biotype was determined by a commercial kit (ID 32C, bioMérieux, France). Oral yeasts were detected in 34.3% of the marginal periodontitis patients and 42.2% of the healthy subjects. Among the sites examined, the buccal mucosa was the major site for yeasts, being colonized in 31.4% of the marginal periodontitis patients and in 35.6% of the healthy subjects. Two genera (Candida and Saccharomyces), four species (C. albicans, C. dubliniensis, C. parapsilosis and S. cerevisiae) and 19 biotypes were identified from the marginal periodontitis patients, while one genus (Candida), two species (C. albicans and C. dubliniensis) and 11 biotypes were obtained from the healthy subjects. C. albicans was the most dominant species in all the oral sites. Among the other Candida species, C. dubliniensis dominated, being most prominent in the periodontal pockets. Two biotypes (7146340015 and 7347340015) of C. albicans and one biotype (7142100015) of C. dubliniensis were predominant in the marginal periodontitis patients, whereas three biotypes (7146340015, 7147340015 and 7347340015) of C. albicans dominated in the healthy subjects. The differences in the distribution of yeast species and biotypes may suggest cell, tissue or site tropism in oral yeast colonization.

A diversity of species and phenotypes was found among the yeasts in thrush and denture stomatitis. Candidal commensals were predominant in thrush and denture stomatitis, but the observation of divergent Candida species and biotypes, constituting 23% of all the yeast isolates, should not be ignored.