Cultural and molecular characterization of tetracycline resistant microflora associated with dental caries

Dental caries is the most common chronic disease. Tetracycline is commonly used in dentalpractice as a prophylactic agent and for treatment of oral infections. The wide use of tetracycline hadresulted in a major increase in the rate of tetracycline resistance among bacteria. Substantial epidemiologicevidence links Streptococcus mutans to caries; the pathobiology of caries may involve more complexcommunities of bacterial species. Molecular methods for bacterial identification and enumeration now makeit possible to more precisely study the micro biota associated with dental caries. The purpose of this studywas to characterize the tetracycline resistant microorganism associated with the dental caries using cultural& molecular method. The first step involved 20 samples from patients with different level of dental caries.From which 33 different isolates were obtained, out of which 12 showed resistances to tetracycline and 5were having maximum MIC indicating that they are highly resistant. These resistant microorganisms wereidentified to the species level by growing them on a suitable medium using the antibiotic tetracycline andwere analyzed with the help of FAME analysis, which indicated that different strains of the Pseudomonasaeruginosa and Bacillus subtilis were present.The second step involved identifying the tet k gene in thecultures. Tet k was amplified under standard conditions by using specific primers results. Interestingly, theresults showed that tet k gene was present in all the sample. Tet k gene is involved in imparting the resistantto the tetracycline by acting as a efflux pump. RFLP analyses were used in order to identify the polymorphicforms of the tet k. The HindIII digest suggest that high resistance to tetracycline was acquired due to somemutations in the genome.