Culture and molecular detection of Enterococcus faecalis from patients with failure endodontic treatment and antimicrobial susceptibility of clinical isolates / Cultura e detecção molecular de Enterococcus faecalis de pacientes com insucesso no tratamento endodôntico e suscetibilidade antimicrobiana dos isolados clínicos

ABSTRACT

Objective: The aim of this study was to evaluate the minimal inhibitory concentrations (MIC) of different antibiotic agents against to the most prevalent microorganism found in root-filled canals by culture and molecular approaches. Material and Methods: The microbial samples were taken either from thirty root-filled canals after removal of gutta-percha. Culture methods and 16s rDNA assay were used to identify the E faecails present in the samples. The antimicrobial susceptibilities of the isolates of E faecalis were determined by MIC values using the E test System and interpreted according to the Clinical and Laboratory Standards Institute guidelines. The following antibiotics were used benzylpenicillin, amoxicillin, amoxicillin-clavulanic acid, erythromycin, azithromycin, vancomycin, chloramphenicol, tetracycline, doxycycline, ciprofloxacin, rifampicin and moxifloxacin. Results: E faecalis were isolated (7/30) and detected (13/30) by culture and PCR assay, respectively. All tested E faecalis (n = 12) were highly sensitive to amoxicillin, moxifloxacin, vancomycin, benzylpenicillin and amoxicillin-clavulanic acid. Isolated E faecalis strains were resistant to some antibiotics such as rifampicin (4/12), tetracycline (2/12), doxycycline (1/12), erythromycin (3/12) and azythromycin (8/12). Conclusion: Amoxicillin, amoxicillin-clavulanic acid, benzylpenicillin, vancomycin and moxifloxacin were the most active antibiotics, in vitro, against E faecalis clinical strains, with all the isolates being susceptible Azithromycin and erythromycin were least effective, with none percentage of isolates being susceptible, during laboratory testing. Moreover, E faecalis were identified more frequently by PCR assay than by culture technique.

RESUMO

Objetivo: O objetivo deste estudo foi avaliar as concentrações inibitórias mínimas (CIM) de diferentes antibióticos contra micro-organismos mais prevalentes em canais radiculares pelos métodos moleculares e de cultura. Material e Métodos: As amostras microbianas foram obtidas de trinta canais radiculares após a remoção da gutapercha. Os métodos de cultura e ensaio 16s rDNA foram utilizados para identificar E. faecalis presente nas amostras. As susceptibilidades antimicrobianas dos isolados de E. faecalis foram determinadas pelos valores de CIM utilizando o sistema E teste e interpretados de acordo com as diretrizes CLSI(Clinical and Laboratory Standards Institute). Foram utilizados os seguintes antibióticos benzilpenicilina, amoxicilina, amoxicilina com ácido clavulânico, eritromicina, azitromicina, vancomicina, cloranfenicol, tetraciclina, doxiciclina, ciprofloxacina, moxifloxacina e rifampicina. Resultados: E. faecalis foram isolados (7/30) e detectados (13/30) por cultura e pelo método PCR, respectivamente. Todos E. faecalis (n = 12) foram altamente sensíveis à amoxicilina,moxifloxacina,vancomicina, benzilpenicilina e amoxicilina com ácido clavulânico. Cepas isoladas de E. faecalis foram resistentes a alguns antibióticos como a rifampicina (4/12), tetraciclina (2/12), doxiciclina (1/12), eritromicina (3/12) e azitromicina (8/12). Conclusão: Amoxicilina, amoxicilina com ácido clavulânico, benzilpenicilina, vancomicina e moxifloxacina foram os antibióticos mais ativos, in vitro, contra cepas clínicas de E. faecalis, com todos os isolados sendo suscetíveis. Azitromicina e eritromicina foram menos eficazes, com nenhuma porcentagem de isolados suscetível durante os testes laboratoriais. E ainda, E. faecalis foram identificados mais frequentemente pela técnica PCR do que pela técnica de cultura.