MRSA Eye Infections on the Rise, Treatment Lagging

Brian Hoyle

October 24, 2011

October 24, 2011 (Orlando, Florida) — While the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), particularly the community-acquired form, in ophthalmic infections continues to rise, the scope of the problem is being underrecognized and treatment is often inappropriate, researchers warned here at the American Academy of Ophthalmology 2011 Annual Meeting.

These conclusions come from a multicenter 6-year study of nearly 400 patients by researchers from the Kaiser Permanente Medical Group in Union City, California. The results were presented by coinvestigator Jordon Piluek, MD, from Stanford University in Palo Alto, California.

"Our results from one of the largest known studies analyzing ophthalmic MRSA infections show that while the number of these infections has continued to increase, the extent of the problem has not generally been recognized and treatment has not been inappropriate," said Dr. Piluek.

The rise of MRSA and community-acquired MRSA (CA-MRSA) has been swift. MRSA appeared within a year of the introduction of methicillin in the early 1960s, and was followed about a decade later by CA-MRSA, which causes infection in otherwise healthy and immunocompetent people. By 2000, half of all hospitalizations in the United States were due to CA-MRSA.

Although the problem has been clearly recognized in other aspects of medicine, the situation is far less clear for eye infections. This retrospective study was undertaken at 20 Kaiser Permanente facilities in California. Examination of medical records from 2000 to 2009 identified 399 patients who were culture-positive for MRSA.

The majority of the cases were CA-MRSA (n = 302); the remaining 97 were nosocomial MRSA. The median age of the patients was 45 years, and 52 patients (13%) were newborns who were usually healthy prior to contracting the infection. Most of those affected were white (47%), followed by Hispanic (18%), black (12%), and Asian (10%).

The majority (31%) of infections manifested as conjunctivitis, Dr. Piluek reported. In those infected with CA-MRSA (diagnosis was based on antibiotic-resistance patterns), the female/male ratio was 2:1, and adnexal infection was more common than ocular infection. No association was found with MRSA infection in other family members or with diabetes.

The treatment included incision and drainage and the use of antibiotics, even though 44% of the isolates were resistant to first-line antibiotics.

The prevalence of resistance to first-line antibiotics increased significantly during the study, from 31% in the period from 2002 to 2005 to 48% in the period from 2006 to 2009. All isolates were susceptible to vancomycin, which was not routinely used initially.

"This is a great study that very nicely shows the problem of MRSA," said Richard Allen, MD, PhD, associate professor of ophthalmology at the University of Iowa Health Center, Iowa City.

"The study really hammers home the importance of education of personal physicians and especially emergency physicians, who are often the first to treat. I don't think that there is anywhere in the United States that we are not encountering MRSA, so the results should be nationally important. The results confirm what many of us are seeing day in and day out."

The study was funded by the Kaiser Permanente Group. Dr. Piluek and Dr. Allen have disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2011 Annual Meeting: Abstract 027. Presented October 23, 2011.