Eye Bacteria Getting More Resistant to Older Antibiotics
Researchers advise eye surgeons to switch to newer antibiotics to prevent post-surgical infection
THURSDAY, June 4 (HealthDay News) -- Conjunctival bacteria are becoming increasingly resistant to earlier generation ﬂuoroquinolone antibiotics, and eye surgeons should switch to newer antibiotics to prevent dangerous post-surgical infections, according to a study in the June issue of Ophthalmology.
Jae Lim Chung, M.D., of Yonsei University College of Medicine in Seoul, Korea, and colleagues swabbed conjunctival bacteria samples from 105 eyes that were to undergo refractive surgery. The swabs were cultured and exposed to common antibiotics, including gatifloxacin (GAT), gemifloxacin (GEM), levofloxacin (LEV), moxifloxacin (MOX), and ofloxacin (OFX) to determine antibiotic resistance. The minimum inhibitory concentration (MIC) was determined for each antibiotic and bacteria by E test.
The researchers found that the most common bacteria species cultured was coagulase-negative staphylococci (CNS), which was found in 73 patients. Of those, the bacteria were methicillin-susceptible in 46 patients and methicillin-resistant in 27 patients. The MIC that would inhibit the growth of 90 percent of the methicillin-susceptible bacteria were: OFX, 0.5 μg/ml; LEV, 0.19 μg/ml; GAT, 0.094 μg/ml; MOX, 0.047 μg/ml; and GEM, 0.023 μg/ml. For the methicillin-resistant bacteria MIC90 values were: 32 μg/ml, 4 μg/ml, 1 μg/ml, 0.5 μg/ml, and 0.25 μg/ml, respectively.
"The most effective against conjunctival bacteria isolated from refractive surgery patients were GEM, MOX, and GAT; however, resistance to earlier-generation ﬂuoroquinolones (OFX and LEV) is increasing among methicillin-resistant CNS. It may be a therapeutic option to use newer ﬂuoroquinolones in patients undergoing refractive eye surgery to reduce such infections as methicillin-resistant CNS," the authors conclude.