Abstract
Purpose: :
To investigate the antibiotic sensitivities and visual outcomes of endophthalmitis caused by methicillin-resistant Staphylococcus aureus (MRSA).
Methods: :
A retrospective, consecutive, case series of all patients with culture proven MRSA endophthalmitis seen at the Bascom Palmer Eye Institute from January 1, 1995 - July 1, 2007 were reviewed for antibiotic sensitivities and visual outcomes. Polymicrobial vitreous culture cases and patients with less than 3 months follow-up were excluded. In all cases, intraocular aqueous and vitreous samples were plated on Thioglycolate, blood, chocolate, and Sabouraud’s agar. All isolates were incubated for 18 to 24 hours in a carbon dioxide incubator at 35.5 degrees F. E-test and disc diffusion were used to compare susceptibility patterns.
Results: :
Thirteen patients with endophthalmitis caused by MRSA were included. All isolates were sensitive to vancomycin but all were resistant to penicillin. Only 7 of 13 (54%) were susceptible to gentamicin and 8/13 (61%) were susceptible to clindamycin. MRSA isolates were 92%% (12/13) sensitive to trimethoprim-sulfamathoxazole. MRSA exhibited reduced sensitivities to older generation fluoroquinolones (ocufloxacin 4/11 [36%] and ciprofloxacin 5/11 or [45%]). In a similar fashion, frequent resistance also occurred with the fourth generation fluoroquinolones (moxifloxacin 5/13 or [38%]) and gatifloxacin 5/13 or [38%]).Median presenting VA before treatment was Hand Motions. Post treatment visual outcomes of 20/400 or better occured in 40% of patients at 3 months follow-up but 4 patients were no light perception.
Conclusions: :
In the current study, MRSA isolates exhibited resistance to a wide variety of antibiotics including the fourth generation flouroquinolones. While all MRSA isolates remained sensitive to vancomycin, less than half of MRSA isolates were sensitive to the fourth generation fluoroquinolones, moxifloxacin and gatifloxacin. Visual outcomes were variable but generally poor.
Keywords: endophthalmitis • microbial pathogenesis: clinical studies • retina