Genotypic diversity of Streptococcus mutans found in saliva evidenced by different arbitrary primers

• Grant number: 06/02308-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2006
• End date: July 31, 2007
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Cinthia Pereira Machado Tabchoury
• Grantee: Maria Clara Sayuri Kajiki de Sousa
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

Streptococcus mutans has been considered the main etiological agent of dental caries and may be present in the oral cavity as different genotypes, which could have distinct capacities of virulence. In genotyping studies of S. mutans in the oral cavity, saliva has been considered an important habitat of these microorganisms. In a recent work, Tabchoury et al. (2006) found only one genotype of S. mutans in most of the volunteers’ saliva (85.7%), using OPA-02 primer for AP-PCR reaction (arbitrarily primed polymerase chain reaction). Maybe, if other primers had been used, higher genotypic diversity of S. mutans would have been found. Thus, the objective of this study is to evaluate the genotypic diversity of S. mutans previously isolated from volunteers’ saliva (Tabchoury et al., 2006), using 5 different arbitrary primers by AP-PCR and to verify the agreement degree in the genotypic profile shown by them. For that, 96 isolates of S. mutans will be reactivated in BHI agar. Then, the colony-forming units will be inoculated into tubes with Todd Hewitt Broth (THB) and incubated for 18 h at 37ºC. The tubes will be centrifuged and the genomic DNA of the bacteria pellet will be extracted. After this, the isolates will be genotyped by AP-PCR with the following arbitrary primers: OPA-02, OPA-03, OPA-05, OPA-13 and OPA-18. The amplicons will be separated by electrophoresis in 1.5% agarose gel and stained with ethidium bromide. The pattern of the bands obtained from each primer will be visually compared.