AAO: Dramatic Increase in Ocular MRSA Documented


NEW ORLEANS, Nov. 15 -- The frequency of ocular methicillin-resistant Staphylococcus aureus (MRSA) increased by almost 60% in the first six years of the decade, according to a study reported here.
Action Points
Explain to interested patients that the frequency of a drug-resistant bacteria found in ocular specimens has increased by almost 60% since 2000.
Point out that the resistant strains may not respond to antibiotics frequently used to treat eye infections.
Note that the findings were reported at a medical conference and should be considered preliminary until they appear in a peer-reviewed journal.
The proportion of MRSA isolates in ocular specimens rose from 18.3% in 2000 to 29.1% in 2005, Darlene Miller, D.H.Sc., of the Bascom Palmer Eye Institute in Miami, told attendees at the American Academy of Ophthalmology meeting.
Usually associated with hospital acquisition, ocular MRSA isolates consistent with community-acquired MRSA accounted for almost 20% of the total, she said.
"The findings suggest that the conjunctiva and lids might serve as potential reservoirs for community-acquired MRSA," Dr. Miller said. "The data also indicate that common ocular antimicrobial agents, such as erythromycin and tetracycline, might be inappropriate for treatment of MRSA."
S. aureus is the most common pathogen isolated in association with conjunctivitis, blepharitis, and adjacent soft-skin infections. S. aureus also may appear as resident flora in up to 30% of normal eyes and in up to 2% of patients undergoing cataract surgery, said Dr. Miller.
To evaluate community-associated MRSA profiles in ocular MRSA isolates, Dr. Miller and colleagues reviewed data from multiple sources to identify all MRSA isolates recovered from conjunctiva, eyelids, and orbit from 2000 through 2005. They identified a total of 484 S. aureus isolates, 141 (29%) of which were MRSA.
MRSA as a proportion of all S. aureus isolates increased by 59% from 2000 through 2005, they found. More than half of the MRSA isolates (74/141) exhibited multidrug resistance.
Dr. Miller reported that the source of the isolates was the conjunctiva in 375 cases, eyelids in 97, and orbit in 12. With respect to MRSA isolates, the site of isolation was the conjunctiva in 109 cases, eyelids in 28, and orbit in four.
The proportion of MRSA isolates did not differ significantly by site of isolation.
Hospital-acquired and community-acquired MRSA differ with respect to susceptibility profiles, chromosomal makeup, and virulence, Dr. Miller said. Of the 141 ocular MRSA isolates, 26 (18.4%) had profiles consistent with community-acquired MRSA: 12 each from the conjunctiva and eyelids and two from the orbit.
"The findings show that isolates consistent with community-acquired MRSA can be isolated from ocular sources in the absence of an outbreak," said Dr. Miller.
The study was supported by Research to Prevent Blindness. Dr. Miller had no disclosures.Primary source: American Academy of OphthalmologySource reference: Miller D, Alfonso ED, "Prevalence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) among ocular MRSA isolates" AAO Meeting 2007; Abstract PO293.