Eyeworld

N EWS 22 | EYEWORLD | AUGUST 2019 by Liz Hillman EyeWorld Senior Staff Writer T he only ongoing, annual, nation- wide surveillance study of antibiotic resistance in ocular pathogens in the United States has released preliminary information from its latest set of find- ings, showing some changes in resis- tance, both positive and negative. The Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) study, fund- ed by Bausch + Lomb, began in 2009. As part of the study, researchers have been conducting yearly tracking and antibiotic susceptibility test- ing of ocular infections resulting from Staphy- lococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae. 1,2,3 From 2009 to the preliminary data from 2018, 2,108 S. aureus isolates have been collect- ed. During this timeframe, researchers observed a decrease in methicillin resistance in S. aureus, with 40% of S. aureus isolates in 2018 being methicillin resistant. Though a decrease in resistant strains is positive, 40% is "still quite high," said Penny Asbell, MD, coinvestigator. Many surveillance studies began because of the alarming rate of methicillin resistance observed in staphylococci. Ongoing study tracks antibiotic resistance of ocular pathogens About the doctor Penny Asbell, MD Chair, Department of Ophthalmology Barrett G. Haik Endowed Chair Director, Hamilton Eye Institute University of Tennessee Health Science Center Memphis, Tennessee "If you look at the trend at the beginning of this century, it looked like [resistance] was on the rise and it was going to reach 100%. We don't know what the future will bring, but at the moment it looks like it's topped off," Dr. Asbell said. Dr. Asbell hypothesized this could be due to more awareness about methicillin resistance leading to more judicious use of antibiotics, both among patients and in livestock animals. "Careful use of antibiotics might lead to less or slower development of resistant or- ganisms. One of the key take-homes in any antibiotics discussion is don't overuse them," Dr. Asbell said. There was a significant decrease in S. aureus resistance to azithromycin, ciprofloxacin, tobra- mycin, and chloramphenicol as well. Though S. aureus saw a decreasing trend of methicillin resistance, there was no such decrease among coagulase-negative staphy- lococci. Since 2009, 1,721 coagulase-negative staphylococci were collected. About half of these exhibited methicillin resistance each year. There was increased resistance to tobramycin and decreased resistance to ciprofloxacin over the 10-year timeframe. The preliminary findings were presented at the 2019 Association for Research in Vision and Ophthalmology annual meeting. The data indicate that when an organism is methicillin resistant, it is more likely to be resistant to other antibiotics as well. "Once you identify that a patient isolate is methicillin resistant, that's when the ophthal- mologist or treating clinician should have a heightened level of concern to determine the best options given what we know from surveil- lance studies and the laboratory report," Dr. Asbell said. The findings indicate that antibiotic resis- tance is extremely common, and thus, every eyecare provider is going to come across pa- tients with infections from resistant organisms, Dr. Asbell said. 2018 ARMOR update •414 isolates were col- lected in 2018, com- pared to 2017 rates •Staphylococci showed resistance to: •Azithromycin (52–60%) •Oxacillin/methicillin (30–49%) •Ciprofloxacin (30–31%) •Coagulase-negative staphylococci showed resistance to: •Trimethoprim (25%) •Tobramycin (23%) •Multidrug resistance of three or more antibiotics was especially prevalent in methicillin-resistant staphylococci A laboratory petri dish with Staph colonies Source: Penny Asbell, MD continued on page 23

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