Identification and antimicrobial susceptibility profile of bacteria isolated from primary endodontic infections

Abstract This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients treated at the Dental Clinic of the University of Ribeirão Preto, São Paulo, Brazil. From September to December 2019, samples were obtained from 21 patients with primary endodontic infections. The collections were carried out in triplicate using paper cones placed close to the total length of the root canal. Bacterial isolation was performed in Brain Heart Infusion agar, Blood agar, and other selective culture media cultured at 37°C for up to 48 h under aerobiosis and microaerophilic conditions. The bacterial species were identified using the Vitek 2 automated system. The disk diffusion method on agar Müeller-Hinton was used to assess antimicrobial susceptibility with the recommended antimicrobials for each identified bacterial species. A total of 49 antibiotics were evaluated. Fifteen of the 21 samples collected showed bacterial growth, and 17 bacterial isolates were found. There were 10 different bacterial species identified: Enterococcus faecalis (four isolates), Streptococcus mitis/oralis (three isolates), Streptococcus anginosus (three isolates) being the most common, followed by Staphylococcus epidermidis, Enterococcus faecium, Streptococcus constellatus, Streptococcus alactolyticus, Enterobacter cloacae, Klebsiella variicola, and Providencia rettgeri (one isolate of each species). The analysis demonstrated significant susceptibility to most of the tested antibiotics. However, some Enterococcus isolates resisted the antibiotic's erythromycin, ciprofloxacin, and tetracycline. A Staphylococcus epidermidis isolate was characterized as multidrug-resistant. Five Streptococcus isolates were non-susceptible to all antibiotics tested.

Antibacterial Activity of a New Ready-To-Use Calcium Silicate-Based Sealer

Abstract The aim of this study was to evaluate the antibacterial potential of a calcium silicate-based sealer (Bio-C Sealer, Angelus) against common bacteria in primary and secondary endodontic infections. Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus mutans were exposed to fresh Bio-C Sealer for 24 h by the agar diffusion method (n=5). Additionally, the antibacterial activity was investigated against E. faecalis and S. mutans biofilms (48 h old) grown in discs with 4 mm in diameter and 2 mm in height. (n=3) of set discs of Bio-C Sealer (Angelus), EndoFill (Dentsply-Mallefer), Sealer 26 (Dentsply), AH Plus (Dentsply), Sealapex (Sybron-Endo) and EndoSequence BC Sealer (Brasseler). The antibacterial activity was evaluated by colony forming unity (CFU) counting using ImageJ software. Data were compared by one-way ANOVA followed by Holm-Sidak test (a=5%). Fresh Bio-C Sealer exhibited antimicrobial activity against all bacteria evaluated by agar diffusion method, except for S. mutans. Set discs of all endodontic sealers tested showed similar CFU values for E. faecalis (p>0.05). S. mutans in biofilms showed higher susceptibility to EndoFill compared with the other sealers (p<0.05). In conclusion, the results indicate that fresh Bio-C Sealer does not inhibit S. mutans growth, but exhibits antibacterial activity against E. faecalis, S. aureus, P. aeruginosa and E. coli. After setting, the Bio-C Sealer exhibits an antimicrobial potential comparable to that of the other sealers evaluated in E. faecalis biofilm, but lower than that of EndoFill for S. mutans biofilm.

Resumo O objetivo deste estudo foi avaliar o potencial antibacteriano do novo cimento biocerâmico (Bio-C Sealer, Angelus) contra bactérias comuns em infecções endodônticas primárias e secundárias. Culturas de Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus e Streptococcus mutans foram expostos a amostras frescas do Bio-C sealer durante 24 h pelo método de difusão em agar (n=5). A atividade antibacteriana de amostras dos cimentos Bio-C Sealer (Angelus), EndoFill (Dentsply-Mallefer), Sealer 26 (Dentsply), AH Plus (Dentsply), Sealapex (Sybron-Endo) e EndoSequence BC Sealer (Brasseler) após a presa também foi investigada em biofilmes de 48 h das bactérias E. faecalis e S. mutans, crescidos em discos com 4 mm de diâmetro e 2 mm de altura. A atividade antibacteriana foi avaliada por contagem das unidades formadoras de colônias (UFC) utilizando o software ImageJ. Os dados foram comparados por ANOVA a um critério seguido pelo pós-teste Holm-Sidak (a=5%). Amostras frescas do Bio-C Sealer exibiram atividade antimicrobiana contra todas as bactérias avaliadas pelo método de difusão em ágar, exceto para S. mutans. A análise da formação de biofilme mostrou que todos os cimentos endodônticos testados apresentaram valores similares de UFC para E. faecalis (p> 0,05), enquanto biofilmes de S. mutans foram mais suscetíveis ao EndoFill em comparação com os demais cimentos (p<0,05). Conclui-se que o cimento Bio-C Sealer fresco exibe atividade antibacteriana para E. faecalis, S. aureus, P. aeruginosa e E. coli, mas não inibe o crescimento de S. mutans. Após a presa, o cimento Bio-C Sealer exibe potencial antimicrobiano similar ao dos demais cimentos avaliados em biofilme de E. faecalis, mas inferior ao do EndoFill para S. mutans.

Detection of virulence and -lactamase encoding genes in Enterobacter aerogenes and Enterobacter cloacae clinical isolates from Brazil

ABSTRACT Enterobacter cloacae and E. aerogenes have been increasingly reported as important opportunistic pathogens. In this study, a high prevalence of multi-drug resistant isolates from Brazil, harboring several -lactamase encoding genes was found. Several virulence genes were observed in E. aerogenes, contrasting with the E. cloacae isolates which presented none.

Detection of virulence and ß-lactamase encoding genes in Enterobacter aerogenes and Enterobacter cloacae clinical isolates from Brazil

ABSTRACT Enterobacter cloacae and E. aerogenes have been increasingly reported as important opportunistic pathogens. In this study, a high prevalence of multi-drug resistant isolates from Brazil, harboring several β-lactamase encoding genes was found. Several virulence genes were observed in E. aerogenes, contrasting with the E. cloacae isolates which presented none.