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Paulo J. Bispo, Maria C. Yu, David Stroman, Luís A. Gabriel, Rubens Belfort, Jr., Ana L. Hofling-Lima; Antimicrobial Susceptibility Profile and Ribossomal-Based Identification of Blepharoconjunctivitis Staphylococci Isolates. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1495.
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© ARVO (1962-2015); The Authors (2016-present)
To determine susceptibility patterns and ribosomal-based species distribution of staphylococci isolated from blepharoconjunctivitis (BLEPH) cases.
A total of 709 staphylococci isolated from patients showing infectious BLEPH were included. Isolates were recovered both, at beginning and after 7 days of moxifloxacin 0.5% and dexamethasone 0.1% opthalmic solution treatment. Species-level identification was acomplished by automated ribotyping. Minimal inhibitory concentration (MIC) was determined by reference CLSI broth microdilution method.
S. epidermidis (53%) was the most isolated specie followed by S. aureus (9.7%), S. saprophyticus (8.7%) and S. lugdunensis (6.9%). Oxacillin resistace was observed in 38% of all coagulase-negative staphylococci (CNS), 31.4% of S. epidermidis and 13% of S. aureus. The better in vitro susceptible (S) profile against CNS was achieved by vancomycin (99.7% S) amikacin (99.4%) clindamycin (97.2%) and chloramphenicol (94.8%). MX (MIC50/90 0.06/0.25 µg/ml; 93.1% S) was the most active fluoroquinolone (FQ) agent against CNS followed by CIP (MIC50/90 0.25/1 µg/ml; 91.4% S) and OFX (MIC50/90 0.5/1 µg/ml; 91.1% S). For S. aureus higher percentage of S was achieved by vancomycin (100%) gentamicin (100%) clindamycin (94.2%) and for the three tested FQ (98.6%). However, MX (MIC50 and MIC90 0.06 µg/ml) showed higher in vitro activity and potency than CIP (MIC50 and MIC90 0.5 µg/ml) and OFX (MIC50 0.5 µg/ml and MIC90 1 µg/ml). Susceptibility rates to AZI and TOB was respectively 70.8% and 87.3% for CNS and 72.5% and 87. for S. aureus. FQ resistant rates for staphylococci isolated before and after treatment was respectively 1.8% and 6.4% (p=0.05) for MX; 6.1% and 11.4% (p<0.05) for CIP; 5.7% and 11.4% (p<0.05) for OFX. Ribotyping showed that the same S. epidermidis ribogroup (1095-7) was idenfied in 1 strain isolated before (MIC = 0.06 µg/ml for MX and 0.25 µg/ml for CIP/OFX) and 1 after (MIC = 8 µg/ml for MX and ≥ 64 µg/ml for CIP/OFX) treatment from the same eye . For the other non FQ susceptible isolates there was no correlation between ribogroups identified before and after MX usage.
MX showed best in vitro antimicrobial activity among commonly used eye drops, however, aminoglycosides and lincosamines, also showed good activity. Based on ribrogroup resulsts, MX usage can select FQ resistant subpopulations for a small numer of treated eyes.
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