Analysis of Genetic Mutations in Quinolone Resistance and Virulence Factor Gene Profile of Enterococcus faecalis

ABSTRACT

Purpose@#To investigate the resistance rate of Enterococcus faecalis which is one of the causative strains of endophthalmitis to three fluoroquinolone drugs, the quinolone resistance gene mutation patterns, and the presence of virulence factor genes. @*Methods@#Between April 1, 2014, and January 16, 2018, 416 eyes of 208 patients undergoing cataract surgery, intravitreal injection, or vitrectomy were examined to identify conjunctival commensals. Patients with infective keratitis and infective endophthalmitis were also examined for the presence of E. faecalis. Before the procedure and surgery, samples for identification of conjunctival commensals were collected from the lower conjunctival sac of both eyes. In addition, corneal and vitreous specimens were collected from patients with keratitis and endophthalmitis, respectively. E. faecalis isolated by culturing the samples was tested for drug susceptibility, the presence of gene sequence mutations, and virulence factor genes. @*Results@#In total, 342 strains were identified in samples from the conjunctiva and included six isolates of E. faecalis. The study was conducted with a total of 16 isolates of E. faecalis, including two from cases of keratitis and eight from cases of endophthalmitis. Six of the 16 strains (37.5%) were resistant to quinolone antibiotics. Point mutations were detected mainly in gyrA and parC. The virulence factors esp, efba, asa1, ace, cylA, and gelE were present in the strains and showed no differences between the quinolone-resistant and quinolone-sensitive strains. Gelatinase activity test was negative for all strains. @*Conclusions@#The resistance rate of enterococcal clinical isolates identified in the ocular area was 37.5%. The increase in resistance to quinolone antibiotics seems to be related to the presence of mutations in gyrA and parC genes. E. faecalis identified in the eye is thought to possess the virulence factors genes esp, efba, asa1, ace, cylA, and gelE.