Isolation and molecular detection of Enterococcus faecium from infected root canals: for progressing towards sustainability

Background and objectives. Enterococcus is a lactic acid bacterium that, according to the Lancefield method of serology-based classification, was formerly classified as a group D Streptococcus until 1984. The current study aimed to isolate and molecularly detect E. faecium (EF) from the infected root canal, and to assess the antimicrobial susceptibility of the isolates. Material and methods. Samples were collected from 50 people who had a single root canal tooth with radiographic evidence of apical periodontitis. The transport media were preincubated at 37°C for 30 minutes and vigorously agitated for 60s before use and were then cultured on primary media. Aerotolerance, Gram-staining, synthesis of catalase, trypsin, and indole were used in the preliminary characterization stage. For species-level identification after preservation at 37°C, a variety of biochemical tests were used, including motility tests, carbohydrate fermentation, and the detection of enzymes. DNA extraction was achieved using the PrestoTM Mini gDNA bacteria kit. Amplification of ddI chromosomal genes from EF was accomplished using DNA extracted from these isolates. Antimicrobial sensitivity tests were conducted to investigate the sensitivity and resistance of the target bacteria against 7 antimicrobial agents. Results. The analysis of data revealed that the prevalence of EF was 70% (in 35 of the samples collected). 74% of the Enterococcus isolates tested positive for EF according to PCR findings. The antibiotic sensitivity test results showed that vancomycin and erythromycin resistance was observed in all samples of EF. As many as 94.3% of isolates were resistant to amikacin, 88.7% were resistant to gentamycin, and 91.4 % were resistant to azithromycin. Doxycycline (94.3%) and nitrofurantoin (97.1%) were more effective against the E. faecium isolated from the root canals. Conclusions. The study concludes that the EF bacteria is an important pathogen of root canal infection which is resistant to many antibiotics.