Finally, we discuss that the prevention strategies against oral colonization of nosocomial pathogens include classical methods and novel methods such as Photodynamic therapy, NO based therapy, anti-virulence therapy and other new under investigation antimicrobial strategies.

RNA interference (RNAi) or Post-Transcriptional Gene Silencing is a strong mechanism of gene silencing which is moderated by MicroRNAs (miRNAs), underlying many fields of eukaryotic biology. The miRNAs are small noncoding RNAs and a gene regulation expression system which showing a tissue-specific expression pattern, and inhibits protein synthesis. For the first time, miRNA has been seen in Caenorhabditis elegans. They play an important role in signaling pathways of various diseases especially periodontal disease during periodontal inflammation and oral cancers. The most important miRNAs in periodontal diseases and oral squamous cell carcinoma are miR-142-3p, miR-146a, miR-155, miR-203, and miR- 223. One of the most important diseases in association with gingival infectious is periodontal diseases which if left untreated, would lead to tooth loss. Hence, the aim of the present study is to focus the effects of miRNAs and their targets in diseases which are mentioned above.

Background:The aerobic Actinomycetes are a large group of soil-indwelling bacteria that are distributed in world-wide. These Gram-positive bacteria are most commonly associated with opportunistic infections in both immunocompromised and immunocompetent hosts.Materials and Methods:In this study, three phenotypic and deoxyribonucleic acid (DNA) extraction methods for isolation and identification of Nocardia genus were compared. Samples were taken in five different locations of Isfahan's suburb from hospitals area, parks, agricultural lands, gardens, arid lands with different soil temperature and pH.Results:In this study, showed that slip-buried-method was better than two other phenotypic methods; 14 out of 70 soil samples (20%) were positive for Nocardia spp. DNA of positive samples were extracted with three techniques and DNA extraction by microwave technique was better than others. This technique was confirmed with observation of DNA bands on 1% agarose gel.Conclusions:These bacteria are important in immune deficient patients such as cancer patients, transplant recipients, tuberculosis; acquired immunodeficiency syndrome etc., Their affluence is unsteady in different zones of the world. In this study, among the three phenotypic methods for the isolation of Nocardia slip-buried method was better than other methods. Among DNA extraction techniques, DNA extraction by microwave method would be selective method for DNA extraction of Nocardia spp. compared with others techniques.