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Genetic diversity and persistent colonization of Enterococcus faecalis on ocular surfaces
Daisuke Todokoro1, Hiroshi Eguchi2, Takashi Suzuki3
1Department of Ophthalmology, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8511, Japan. dtodokor@gunma-u.ac.jp.
Japanese Journal of Ophthalmology
|October 17, 2018
Summary
Enterococcus faecalis strains from eye infections show diverse genetic types, with no specific lineages identified. Persistent colonization of the ocular surface by these bacteria was observed in patients with chronic eye conditions.
Area of Science:
- Ophthalmology
- Microbiology
- Genetics
Background:
- Enterococcus faecalis is a significant cause of severe endophthalmitis, often resulting in poor visual prognosis.
- Ocular E. faecalis isolates, including those from conjunctival cultures, may contribute to postoperative endophthalmitis.
- The genetic characteristics of ocular E. faecalis strains remain largely unknown.
Purpose of the Study:
- To characterize the population genetics of Enterococcus faecalis clinical isolates from ocular infections and commensal samples.
- To investigate the genetic diversity and clonal structure of E. faecalis in the ocular environment.
Main Methods:
- Retrospective analysis of 28 E. faecalis ocular isolates from 23 patients.
- Multilocus sequence typing (MLST) and eBURST analysis to determine sequence types (STs) and clonal complexes (CCs).
- Phenotypic analysis of cytolysin and gelatinase production, antibiotic susceptibility, and quinolone resistance-determining region (QRDR) mutations; pulsed-field gel electrophoresis (PFGE) for strain relatedness.
Main Results:
- MLST identified 12 STs, clustered into 3 CCs and 8 singletons, indicating genetic diversity.
- Thirteen isolates (56.5%) belonged to previously reported major CCs (CC58, CC8, CC2).
- High-level quinolone resistance was observed in 26.0% of strains due to gyrA and parC mutations.
Conclusions:
- Ocular E. faecalis isolates exhibit diverse genetic profiles without evidence of eye-specific lineages.
- Persistent colonization of the ocular surface by E. faecalis was confirmed in patients with chronic ocular surface diseases.
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