ABSTRACT

Background: Dental caries is one of the most common and costly diseases in the world and, Streptococcus mutans have been commonly associated as major cariogenic bacteria.

Aim: To evaluate the efficiency of some drugs in Kurdistan against S. mutans   and study antimicrobial activity of ethanolic and aqueous extract of Juglans regia    leave and bark of the walnut   on the same isolates.

Method:  The dental carries samples were collected from 250 students during   October 2017 to April 2018, of both sexes with the mean age of 20 years. Biochemical and molecular identification were used for bacterial identification then antibiotic susceptibility assessed by disc diffusion method by using twenty antibiotics. Aqueous and alcoholic extracts of Juglans regia leaves and barks were used for inhibition the growth of isolated bacteria

Results: 80 isolates of Streptococcus mutans   were identified, there was a wide range of resistant S. mutans against antibiotics, the resistance started from 15% as low percentage of all isolates against each of MY, VA, N and NA antibiotics while, the high percentage of resistance was 95% toward ME and DO.  The minimum inhibitory concentration (MIC) for alcoholic and aqueous extracts of Juglans regia was 1400, and 1800 µg/ml respectively, ethyl and methyl alcoholic extracts of both parts most effective against S. mutans than aqueous extract.

Conclusion:   Juglans regia   is considered one of the most likely preferable alternative medical plant that used to treat dental caries to avoid the upcoming bacterial resistance to the antibiotic.

 Keywords:  S. mutans, J. regia.  antibiotics