Occurrence, Population Structure, and Antimicrobial Resistance of Enterococci in Marginal and Apical Periodontitis

Abstract

Subgingival plaque samples and root canal samples were collected from 2,839 marginal periodontitis (MP) patients and 21 apical periodontitis (AP) patients. Enterococcus species were identified by a series of phenotypic and genotypic tests. Antimicrobial susceptibility assays were performed by an agar disk diffusion test. Multilocus sequence typing (MLST), eBURST, and minimum spanning tree were used for enterococcal genetic clustering and population analysis. Enterococcus faecalis was recovered from 3.7% MP patients and 9.5% AP patients, and Enterococcus faecium was recovered from 0.04% MP patients. Enterococci were detected more often in older male patients. E. faecalis isolates of MP were found resistant to tetracycline (49.1%), erythromycin (8.5%), trimethoprim (2.8%), and gentamicin (1.9%), while one AP isolate was resistant to tetracycline. A total of 40 sequence types (STs) were resolved in 108 E. faecalis isolates. Comparison with E. faecalis international MLST database revealed that 27 STs were previously found, 13 STs were novel, and several major clonal complexes in the database were also found in MP isolates. The tetracycline-resistant isolates distributed mainly in the major clonal complexes and singletons, whereas the erythromycin-resistant isolates were more dispersed. Although the rate of occurrence of enterococci recovered in the MP and AP samples was low, 50% of these isolates are resistant to at least one antimicrobial agent, which is most often tetracycline. This implies that subgingival E. faecalis might represent a reservoir of resistance to tetracycline and erythromycin. The subgingival E. faecalis isolates show high genetic diversity but are grouped, in general, with the known isolates from the international database.

Capsule Locus Polymorphism among Distinct Lineages of Enterococcus faecalis Isolated from Canals of Root-filled Teeth with Periapical Lesions

“…The genetic diversity revealed by MLST in this study was similar to previous reports from oral (11,17,18) and non-oral (4) E. faecalis isolates. Comparison of our data with the international MLST database revealed common STs among root canal isolates and strains isolated from hospitalized patients, feces of healthy individuals, animals, and food.…”

“…Comparison of our data with the international MLST database revealed common STs among root canal isolates and strains isolated from hospitalized patients, feces of healthy individuals, animals, and food. Thus, the oral E. faecalis strains should be cross-transmitted from diverse sources, confirming previous findings (18). Also, the data support the hypothesis that food might be one possible source of E. faecalis in root canal infections (19), because STs 23, 25, 40, 72, and 133 detected in 9 of 22 cases were previously detected in food samples.…”

Enterococcus faecalis affects the proliferation and differentiation of ovine osteoblast-like cells

“…E. faecalis also shows resistance, intrinsically or via acquisition, to a wide range of antibiotics [9,10] and can invade in dentinal tubules, where its elimination by root canal disinfectants seems to be a formidable challenge [11]. Finally, E. faecalis colonizes the root canal as monocultures, organizes in biofilms without the need for support of other bacteria [12,13], and possesses a wide array of putative virulence factors that bring about pathological alterations either directly through toxin production or indirectly through the activation of the host immune system.…”

Clonal diversity and antimicrobial resistance of Enterococcus faecalis isolated from endodontic infections

“…These results clearly indicate that the morphology, physiology and biochemical reactions of bacterial strains may be similar, but a point mutation resulting in a change in the DNA base pair regimen can result in organisms that are either very susceptible or very resistant to many antibiotics, raising concerns for clinicians [40].…”