| dc.description | Aim To test, in vitro, the susceptibility to different antibiotics of Enterococcus faecalis isolates from canals of root filled teeth with periapical lesions. Methodology Twenty-one E. faecalis isolates, from canals of root filled teeth with persisting periapical lesions, were tested for their antibiotic susceptibilities. The following antibiotics were used: benzylpenicillin, amoxicillin, amoxicillin-clavulanic acid, erythromycin, azithromycin, vancomycin, chloramphenicol, tetracycline, doxycycline, ciprofloxacin and moxifloxacin. Minimal inhibitory concentrations (MICs) for the antimicrobial agents were determined using the E-test System (AB BIODISK, Solna, Sweden), and the E. faecalis strains classified as susceptible or resistant according to the guidelines of National Committee for Clinical Laboratory Standards (NCCLS). The strains were also tested for beta-lactamase production with nitrocefin (Oxoid, Basingstoke, UK). Results All strains were susceptible to penicillins in vitro, however, the MICs of amoxicillin and amoxicillin-clavulanic acid (MIC90 = 0.75 mug mL(-1)) were lower than for benzylpenicillin (MIC90 = 3.0 mug mL(-1)). All strains studied were also susceptible to vancomycin and moxifloxacin, whilst 95.2% were susceptible to chloramphenicol. Amongst the isolates, 85.7% were susceptible to tetracycline and doxycycline and 80.9% to ciprofloxacin. The MIC of erythromycin ranged from 0.38 to >256 mug mL(-1); only 28.5% of the strains were susceptible (MIC less than or equal to 0.5 mug mL(-1)). Limited susceptibility was also observed with azithromycin which was active against only 14.2% of isolates. No strains produced beta-lactamase. Conclusion Enterococcus faecalis isolates were completely susceptible, in vitro, to amoxicillin, amoxicillin-clavulanic acid, vancomycin and moxifloxacin. Most isolates were susceptible to chloramphenicol, tetracycline, doxycycline or ciprofloxacin. Erythromycin and azithromycin were least effective. | |
