Visual outcome and bacterial sensitivity after methicillin-resistant Staphylococcus aureus-associated acute endophthalmitis.

PURPOSE: To determine the frequency, visual outcome, and bacterial sensitivity in cases of methicillin-resistant Staphylococcus aureus (MRSA)-associated acute postoperative endophthalmitis occurring after cataract surgery.

DESIGN: Retrospective, consecutive, observational case series.

METHODS: Sixty-four cases of acute endophthalmitis occurring within six weeks after cataract surgery were identified over a three-year interval at a single vitreoretinal practice. Cases related to MRSA were studied and visual outcomes and bacterial sensitivities were recorded.

RESULTS: Thirty-three of the 64 eyes were culture positive, and six of the 33 cases (18.2%) demonstrated MRSA infection. All six eyes were started on fluoroquinolone antibiotics two or three days before surgery. Corneal abnormalities were noted in five of the six cases (83.3%), ranging from wound infection to diffuse corneal opacification. Visual acuity at last follow-up was no light perception (NLP) in two eyes, hand movements in two eyes, and 20/30 or better in two eyes. One eye with NLP vision underwent enucleation within three days of presentation because of panophthalmitis and impending sepsis. All six organisms were sensitive in vitro to both gentamicin and vancomycin. No organism was sensitive to any fluoroquinolone antibiotic, although not all organisms were tested against all fluoroquinolones.

CONCLUSIONS: MRSA infection accounts for 18% of culture-positive cases of endophthalmitis in this study and was associated with a poor visual outcome in two-thirds of our patients. MRSA organisms may be resistant in vitro to all generations of fluoroquinolone antibiotics, but do seem to be sensitive to gentamicin and vancomycin. The incidence of MRSA endophthalmitis seems to have increased significantly since the Endophthalmitis Vitrectomy Study was published in 1996.