Abstract
Purpose: :
To survey the emergence of multi-drug resistance Corynebacterium from ophthalmic samples in Japan and to characterize the mutations in the gyrA gene.
Methods: :
This study includes 43 strains of Corynebacterium that were isolated from conjunctival swabs before ocular surgeries or discharges of conjunctivitis cases at 12 institutes in Japan during the period from August to November 2007. The species assignment of these isolates was made by the sequence analysis of the 16S ribosomal RNA gene (rDNA). The genomic DNA of each strain grown in brain heart infusion broth containing 0.1% Tween 80 was purified and the QRDRs of the gyrA gene were analyzed. The minimal inhibitory concentrations (MICs) of several types antimicrobials were determined by the E-test method.
Results: :
The majority of isolates (36/43) were assigned to C. macginleyi, while the remainings were identified six other species (two C. mastitidis, one C. accolens one C. amycolatum, one C. fastidiosum, one C. propinquum and one C. pseudogenitalium). The resistance rates of all strains to quinolones (CPFX, LVFX, NFLX), EM, TOB, GM and DOXY were 69.8%, 44.2%, 13.9%, 7.0% and 2.3% respectively. No resistant strain to IP, CTRX, VCM and TEIC were found. All of the high-level fluoroquinolone-resistant isolates possessed double mutations generating changes in Ser-83 and Asp-87 when compared to the susceptible isolates.
Conclusions: :
This survey reveals that C. macginleyi is dominant on the Japanese ocular surface and indicates that high-level fluoroquinolone resistance in C. macginleyi relate with amino acids changes in the gyrA. The susceptibility to drugs tends to be low in antimicrobials that are commercially available as eye drops.
Keywords: microbial pathogenesis: clinical studies • conjunctiva