Abstract
In vitro eradication of theC. albicansandS. mutansmixed biofilms by eugenol alone and in combination with the antimicrobial drugs. Previously characterized strains ofC. albicans(CAJ-01 and CAJ-12) andS. mutansMTCC497 were used to evaluate the eradication of biofilms using XTT reduction assay, viability assay, time dependent killing assay and scanning electron microscopy (SEM). Synergistic interaction was assessed by checkerboard method. Sessile MIC (SMIC) of eugenol was equivalent to the planktonic MIC (PMIC) againstC. albicansandS. mutansmixed biofilms. SMIC of fluconazole and azithromycin was increased upto 1000-folds over PMIC. Eradication of single or mixed biofilms was evident from the viability assay and SEM. At 1 x MIC of eugenol, log(10)CFU count ofC. albicanscells were decreased from 6.3 to 4.2 and 3.8 (p < 0.05) in single and mixed biofilms, respectively. SEM studies revealed the eradication ofC. albicansandS. mutanscells from glass surface at 800 mu g/mL concentration of eugenol. Time dependent killing assay showed dose dependent effect of eugenol on pre-formed CAJ-01, CAJ-12 andS. mutansbiofilm cells. Eugenol was highly synergistic with fluconazole (FICI = 0.156) against CAJ-12 single biofilms. However, the combination of eugenol and azithromycin showed maximum synergy (FICI = 0.140) against pre-formedC. albicansandS. mutansmixed biofilms. These findings highlighted the promising efficacy of eugenol in the eradication of biofilms of two oral pathogens (C. albicansandS. mutans) in vitro and could also be exploited in synergy with fluconazole and azithromycin in controlling oral infections.