Abstract
Purpose :
Antibiotic resistance is a serious concern in the treatment of bacterial eye infections. The ongoing Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) study is the only nationwide antibiotic resistance surveillance program specific to ocular pathogens. Here we report preliminary results for ocular isolates collected in 2016.
Methods :
Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae isolates were collected and subjected to antibiotic susceptibility testing. Minimum inhibitory concentrations were determined by broth microdilution for up to 16 antibiotics according to the Clinical and Laboratory Standards Institute guidelines. Isolates were categorized as susceptible or non-susceptible (intermediate and resistant) based on systemic breakpoints, where available.
Results :
A total of 359 isolates were collected from 11 participating US sites. H. influenzae isolates collected to date from 2016 were susceptible to all antibiotics tested. Although resistance among P. aeruginosa isolates continued to be low, preliminary 2016 data indicate that non-susceptibility to fluoroquinolones (7%) more than doubled from 2015. Isolates of S. pneumoniae exhibited non-susceptibility to azithromycin (31%) and penicillin (38%) while remaining susceptible to fluoroquinolones and chloramphenicol. Resistance rates for S. aureus and CoNS generally remained steady when compared to 2015 data. Among all staphylococci, resistance was most notable for azithromycin (47-63%), oxacillin/methicillin (27-43%), and ciprofloxacin (25-30%), with CoNS isolates also exhibiting high levels of non-susceptibility to tobramycin (20%) and trimethoprim (36%). Non-susceptibility to three or more drug classes was observed in 24% of S. aureus and 36% of CoNS isolates collected in 2016, with multidrug resistance remaining prevalent among methicillin-resistant (MR) S. aureus (70%) and MRCoNS (77%).
Conclusions :
Preliminary 2016 ARMOR surveillance data show continued high levels of antibiotic resistance among staphylococci, especially among MR strains, with many isolates demonstrating multidrug resistance. Continued surveillance of ocular pathogens is warranted, and susceptibility data obtained from ARMOR should be considered before initiating empiric treatment of common eye infections.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.