Molecular Detection of Fluoroquinolone resistance Genes in Enterococcus spp. Isolated From Dental Root Canals Infections

Abstract

Enterococcus is among the most prevalent bacterial species identified in teeth exhibiting pulp necrosis that have not undergone prior endodontic treatment. Enterococcus bacteria exhibits considerable resistance to numerous root canal disinfectants, often posing a treatment challenge. This study aims to isolate and identify Enterococcus species using both phenotypic and molecular methods. The phenotypic patterns were determined through biochemical techniques, followed by diagnosis based on genotypes utilizing specialized primers for the 16S rRNA and D-Ala:D-Ala ligase genes via polymerase chain reaction. The evolution of resistance strains presents substantial challenges to infection treatment, necessitating the creation of novel antibiotics. To attain this objective, it is essential to investigate the primary genes implicated in antibiotic resistance. Fifty samples were obtained from individuals of different ages and sexes suffering from root canal infections between January 2025 and March 2025, and were subsequently grown in selective and differential media. Susceptibility tests indicated that 50% of the isolates exhibited resistance to ciprofloxacin, 62.5% to levofloxacin, and 62.5% to nofloxacin. The results revealed 8 (16%) isolates of E. faecalis and no isolates of E. faecium. The 16s rRNA, ddl E. faecalis, GyrA, ParC, and ParE genes were detected with a frequency of 100%, while the GyrB gene was detected with a prevalence of 62.5%, and the ddl faecium gene was absent in all samples. The presence of resistance genes enables bacteria to evade antibiotic actions and persist in the root canal, resulting in the failure of endodontic treatment.