ABSTRACT
Garlic [Allium sativum] extract has an inhibitory effect on various pathogenic bacteria, viruses and fungi. The aim of the present study was to evaluate in vitro inhibitory effect of garlic extract on multi-drug-resistant [MDR] strains of Streptococcus mutans isolated from human carious teeth. Filtered sterilized aqueous extract of garlic was used in the present study. In this in vitro case-control study data was analyzed with Student's t-test [? = 0.05]. From 105 extracted human carious teeth 92 strains of S mutans were isolated. Disk sensitivity tests and broth dilution methods were used to determine antibiotic sensitivity profile and inhibitory activity of garlic extract on S mutans. Among 92 isolates of S mutans, 28 [30.4%] were MDR since they were resistant to four or more antibiotics. The highest and least resistance rates were observed for tetracycline [30.4%] and teichoplanin and vancomycin [0%], respectively; on the other hand, 22.8% and 23.9% of the isolates were resistant to penicillin and amoxicillin, respectively. Chlorhexidine minimum inhibitory concentration [MIC] for MDR and non-MDR S mutans varied from 2 to 16 microg/mL and from 0.25 to 1 microg/mL, respectively [p value < 0.05]. All the isolates, MDR and non-MDR, were sensitive to garlic extract with the MIC ranging from 4 to 32 mg/mL. Considering the data obtained from the present study, mouthwashes or toothpastes containing optimum concentrations of garlic extract can be used for the prevention of dental caries