Background: Enterococcus faecalis
is considered to be one ofmost prevalent species in the oral cavity, particularly
in endodontic infections. The aim of the present study was to investigate the prevalence of
E. faecalis in dental
root canals, clonal diversity by restriction fragment length polymorphism (RFLP) and randomly amplified
polymorphic DNA (RAPD-PCR) analysis, and the antibiotic susceptibility of
E. faecalis isolates.
Results: Among the bacterial strains isolated from dental root canal specimens (n = 82),
E. faecalis was
determined to have the highest prevalence followed by
Streptococcus viridians,
Leuconostoc mesenteroides
,
Staphylococcus aureus
,
Streptococcus mitis
, and
Pediococcus pentosaceus
. Cluster analysis of RAPD-PCR and RFLP
patterns of the
E. faecalis isolates discriminated five and six different genotypes, respectively. Among the tested
strains, 43%, 52% and 5% were susceptible, intermediate resistant, and resistant to erythromycin, respectively.
In addition, one strain (E-12) was intermediate resistant to linezolid, and one isolate (E-16) was resistant to
tetracycline. Interestingly, many of the intermediate resistant/resistant strains were grouped in clusters 5 and
6, according RAPD and to RFLP, respectively.
Conclusions: E. faecalis demonstrated the highest prevalence in the tested dental root canal specimens collected
from Saudi patients and were grouped into five to six different genotypes. Different levels of antimicrobial
susceptibility were observed in the tested
E. faecalis strains, which clearly indicated that although bacterial
strains may be similar, point mutations can result in extreme susceptibility or resistance to various antibiotics.
This phenomenon is a cause for concern for clinicians in the treatment of dental infections caused by
E. faecalis.
