antibiotic resistance of streptococcus spp. isolated from the root surface of extracted teeth to penicillin v and clindamycin using e-test

Background: antibiotics are used to treat and prevent oral infections. clindamycin and penicillin are widely used drugs in this field. poor use of antibacterial agents causes the emergence of antibiotic-resistant bacteria. objectives: the present study examined and compared the frequency distribution of resistance of streptococci isolated from the root surface of extracted teeth to penicillin v and clindamycin. this study was conducted in 2021 in yazd, iran. methods: this was an analytical cross-sectional study performed in vitro. the samples were taken from the root surfaces of 50 teeth immediately after extraction and transferred to the laboratory in a transfer medium. after cultivation, isolation, and identification, the antibiotic resistance of isolates was measured by the e-test method. the data were analyzed using spss software (version 23). results: streptococcispp. were isolated from 46 samples (92%) without environmental contamination. the minimum inhibitory concentration (mic) 50 and mic 90 for penicillin v were 0.5 μg/ml and 1 μg/ml, respectively, and for clindamycin, 0.125 μg/ml and 0.19 μg/ml, respectively, which was significantly (p = 0.0001) lower for clindamycin. intermediate sensitivity to penicillin v was 95.6%, and resistance to clindamycin was 21.8%. conclusions: it seems that except in limited cases where there is resistance to clindamycin, this antibiotic is a more effective drug to control the bacteria in the mouth. however, in some cases, aerobic isolates showed intermediate sensitivity to penicillin v; instead, resistance to clindamycin was observed.