MONDAY, Sept. 12 (HealthDay News) -- Repeated use of antibiotics
among patients who receive eye injections for such ophthalmic
conditions as age-related macular degeneration can lead to the
emergence of drug-resistant germs, according to a new study.
More than eight million people in the United States are affected
by age-related macular degeneration, and its treatment involves
monthly injections that are typically followed by antibiotics to
prevent such complications as inflammation of the eye.
Researchers from Vanderbilt University School of Medicine in
Nashville found, however, that long-term use of antibiotics after
eye injection therapy may promote the growth of hard-to-treat
"Repeated exposure of ocular flora [microbes living on or inside the body] ... may select for resistant bacterial strains and cultivate 'superbugs' with multiple-drug resistance ..." the study's authors wrote a news release from Archives of Ophthalmology, which published the results Monday in its September issue.
In conducting the study, the researchers followed 24 patients
receiving monthly eye injections in just one of their eyes for at
least four months in a row. Each patient was given one of four
antibiotics to use following their injection. After each treatment,
the researchers cultured, or looked for bacteria, on the surface
and the inner lid of both the treated and non-treated eyes.
The bacteria the researchers found was analyzed and tested to
determine how vulnerable it was to 16 different antibiotics.
The study found that ongoing exposure to certain antibiotics
(fluoroquinolones and azithromycin) was associated with the growth
of drug-resistant bacteria, known as coagulase-negative
Specifically, 81.8 percent of CNS samples taken from treated
eyes appeared resistant to at least three antibiotics, and 67.5
percent appeared resistant to at least five antibiotics.
The researchers concluded that repeated use of eye antibiotics
leads to CNS resistance to certain antibiotics. As a result, they
said, doctors and patients should be more cautious about how eye
antibiotics are prescribed and used to avoid the spread of
The U.S. National Institutes of Health provides more information