Evaluation of antimicrobial susceptibility of facultative anaerobic bacteria isolated in root-filled teeth with persistent infection front to use of systemic antibiotics

AbstractIntroductionBacteria associated with failure endodontic treatment are capable of acquiring and expressing resistance against antimicrobial agents usually used to treat infections, which makes necessary, in some cases, laboratory tests in order to detect the resistance or antimicrobial susceptibility of these microorganisms.Objectiveto evaluate the antimicrobial susceptibility of Enterococcus faecalis, Enterococcus faecium, Actinomyces viscosus and Staphylococcus aureus strains isolated from root canals of teeth with failure endodontic treatment.Material and methodEnterococcus faecalis (n=3), Enterococcus faecium (n=3), Actinomyces viscosus (n=3) and Staphylococcus aureus (n=3) clinical strains collected in vivo from root-filled canals with failure endodontic treatment thad been their antimicrobial susceptibility tested by the E-test method in duplicate using the antibiotics: Amoxicillin (AC), Rifampicin (RI), Moxifloxacin (MX), Vancomycin (VA), Tetracycline (TC), Ciprofloxacin (CI), Chloranphenicol (CL), Benzilpenicillin (PG), Amoxicillin + clavulanic acid (XL), Doxycycline (DC), Erythromycin (EM) e Azithromycin (AZ).Resultall the clinical strains tested were susceptible to AC, XL, PG, DC, MX, TC e VA. All the isolated S. aureus strains were susceptible to the 12 tested antibiotics. E. faecalis, E. faecium and A. viscosus strains showed intermediary susceptibility pattern against EM. Some E. faecalis and E. faecium strains were resistant against AZ and RI.Conclusionclinical strains isolated from radicular canals of teeth with failure endodontic treatment showed different antimicrobial susceptibility profiles, and none of E. faecalis or E. faeciumstrains appeared to be susceptible to AZ or EM.