Topical Antibiotics After Eye Injections May Be Harmful

Larry Hand

October 26, 2013

The use of topical antibiotic drops after intravitreal injections may do more harm than good, , according to a large study published online October 21 in Ophthalmology. Rather than reducing the risk of endophthalmitis, antibiotic drops may have actually increased the risk and contributed to antibiotic resistance.

"I think this should be practice-changing.... I have already stopped using topical antibiotics for intravitreal injections, and I think many people may follow suit," said John I. Loewenstein, MD, associate chief of ophthalmology for clinical affairs at the Massachusetts Eye and Ear Infirmary and vice chair for education in ophthalmology at Harvard Medical School, Boston.

Dr. Loewenstein, who was not involved in the newly reported study, notes that these new data confirm what have been seen in several other studies.

Risk Increased 50% In Case-Control Study

Philip Storey, MD, MPH, from the Wills Eye Hospital, Thomas Jefferson University, Philadelphia, Pennsylvania, and colleagues on the Post-Injection Endophthalmitis Study Team conducted a retrospective case-control study of endophthalmitis cases at their institution between January 1, 2009, and October 1, 2012.

During that time, Wills physicians performed 117,171 office-based intravitreal injections, including 57,654 during a period when topical antibiotics were used, 24,617 during a transition period, and 34,900 during a period when topical antibiotics were not used.

A total of 44 cases of suspected endophthalmitis developed (0.038%; 1/2663 injections): 28 cases during the 24 months that antibiotics were used (0.049%; 1/2059 injections), 5 cases during the 8-month transition (0.020%; 1/4923 injections), and 11 cases during the no-antibiotic period of 9 months (0.032%; 1/3173 injections).

The researchers found that topical antibiotic use was associated with a greater than 50% increased risk for endophthalmitis (odds ratio [OR], 1.54; 95% confidence interval [CI], 0.77 - 3.10) and culture-positive endophthalmitis (OR, 1.51; 95% CI, 0.47 - 4.85).

"Despite the fact that endophthalmitis may occur in only 1 of 3000 injections, when you look at the number of injections given each year to each patient, the number of people who could develop that problem is quite large," senior author Sunir J. Garg, MD, told Medscape Medical News.

"If injections are done once a month or once every other month, then patients were getting short courses of antibiotics 6 to 12 times a year, which our group and other groups have found increases resistance not only to antibiotics for the eyeball, but because of the tear duct next to the eye in the back of the nose and throat, those antibiotics may also have unintended consequences for the nose and throat," Dr. Garg continued.

Highly Common Procedure

Intravitreal injection is one of the most common eye procedures performed. Injections deliver antivascular endothelial growth factor (VEGF) medications, including ranibizumab, bevacizumab, and aflibercept, for treating ocular disorders such as diabetic retinopathy and macular degeneration.

For the cases of endophthalmitis in this study, common infections were from Streptococcus viridians, Enterococcus, Staphylococcus, Staphylococcus aureus, and Lactobacillus. "Some infections such as Streptococcus can be destructive to the eyeball," Dr. Garg said.

Best Level of Evidence Available

"There have been a number of studies before that point in the same direction. If anything, there's a trend, not only in this study but in others, toward more infection in groups that get the antibiotics," Dr. Loewenstein told Medscape Medical News.

"This is not a gold standard prospective randomized trial, but given the numbers that you would need for that, since endophthalmitis is so rare after injection, that study will never be done. So this is the next best level of evidence, and there've been several studies that are kind of at this level of evidence showing the same thing," he continued. The current study is the largest to date, according to the authors.

He added, "Every injection carries the same risk. The more times you roll the dice, the more likely you are to get an infection. There are some patients with macular degeneration who are dependent on almost monthly injections for a long, long time. Patients have been relieved not to have to take [the antibiotics]. The only resistance comes from the bacteria."

Practical Issue

Reducing the use of antibiotics is also cost effective, according to Dr. Garg. Although some $10 generic antibiotics are used, other branded antibiotics cost $200 a bottle, he said. "It's possible that 1 bottle may last for 2 or 3 applications, but some people throw them away after 1 application. From a cost-effective perspective, if there's not real benefit from them, then why subject a patient to an unnecessary expense."

The authors and Dr. Loewenstein have disclosed no relevant financial relationships.

Ophthalmology. Published online October 21, 2013. Abstract

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