In–Vitro Resistant Rates for Fluoroquinolone Antibiotics Against Methicillin Resistant Staphylococcus Aureus (MRSA) Ocular Isolates From Different Geographic Locations.

Abstract

Abstract: : Purpose: To benchmark and compare emerging resistance patterns of the new 4^th generation fluoroquinolones against older ophthalmic fluoroquinolone agents for Methicillin–Resistant Staphylococcus Aureus (MRSA) ocular pathogens recovered from patients presenting in New York and South Florida. Methods: 30 MRSA ocular isolates archived at the Bascom Palmer Eye Institute (BPEI) and 65 MRSA ocular isolates archived at the New York Eye and Ear Infirmary (NYEEI) from corneal ulcer or endophthalmitis cases were tested for in vitro susceptibility against moxifloxacin, gatifloxacin, ofloxacin and ciprofloxacin with either E–test strips or disk diffusion tests to generate susceptibility patterns. Results: In vitro resistance rates for the MRSA isolates at the BPEI, were: moxifloxacin (24/30,80%), gatifloxacin (25/30,83%), ciprofloxacin (27/30,90%) and ofloxacin (27/30,90%). In vitro resistance For the MRSA isolates at the NYEEI: were: moxifloxacin (46/65,71%), gatifloxacin (48/65,74%), ciprofloxacin (59/65,91%) and ofloxacin (59/65,91%). Total in vitro resistance for all isolates were: moxifloxacin (70/95,74%), gatifloxacin (73/95,77%), ciprofloxacin (86/95,91%) and ofloxacin (86/95,91%%). Conclusions: A surprisingly high rate of in vitro resistance was documented for all generations of fluoroquinolone antibiotics against MRSA ocular isolates in both geographic locations. This is in contrast to the relatively low resistance rates seen with 4^th generation fluouroquinolone antibiotics against most gram–positive isolates. As with all in vitro studies, laboratory results must be correlated with clinical treatment and outcome studies

Keywords: antibiotics/antifungals/antiparasitics • clinical laboratory testing • microbial pathogenesis: experimental studies