The Relationship between Cell Surface Hydrophobicity and Antibiotic Resistance of Streptococcal Strains Isolated from Dental Plaque and Caries

Objective Bacterial adhesion is governed by specific and nonspecific interactions such as hydrophobicity. Hydrophobic interactions play a role in the adherence of microorganisms to a wide variety of surfaces and facilitate biofilm formation due to bacterial adhesion. In this article the relation between cell surface hydrophobicity and antibiotic resistance was studied. Materials and Methods We studied antibiotic susceptibility of isolated Streptococci from dental plaque and caries (by disk diffusion method) and cell suface hydrophobicity (by microbial adhesion to hydrocarbon). Results The results indicated that the mean surface hydrophobicity of all mutans and other than mutans Streptococci, without considering their location (caries or plaque) showed significant differences (mean ۷۸%, ۵۹%, respectively). No significant differences among caries and plaque isolated Streptococci were found regarding the antibiotic susceptibility. Chi square test with contingency table showed significant qualitative correlation between classes of hydrophobicity (high, moderate and low) and antibiotic resistance (p= ۰.۰۰۱), but according to the regression models we could not find any linear correlation between cell surface hydrophobicity and the diameter of inhibition zone for each antibiotic separately. Conclusion The high overall proportion of hydrophobic bacteria found in this study suggests that cell- surface hydrophobicity may play a role in adherence of certain oral species to the tooth surface. If bacteria attach to surfaces and form biofilm they can be more resistant, but these two factors (antibiotic resistance and cell surface hydrophobicity) did not show a linear correlation in this study.

Keywords:

Antibiotic resistance , Dental plaque and caries , Hydrophobocity , Streptococcus mutans