Abstract
Purpose :
Antibiotic resistance poses a serious threat to the successful treatment of bacterial eye infections. The ongoing Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) study remains the only nationwide surveillance program which tracks in vitro antibiotic susceptibility profiles among ocular bacterial pathogens of significance. Here, we report results from isolates collected to date in 2018.
Methods :
Clinically relevant isolates of Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae from ocular infections were collected from ARMOR-participating sites and subjected to antibiotic susceptibility testing. Minimum inhibitory concentrations were determined by broth microdilution for up to 16 antibiotics (10 classes) according to the Clinical and Laboratory Standards Institute guidelines. Isolates were categorized as susceptible or resistant (intermediate plus full resistance) based on systemic breakpoints, where available.
Results :
A total of 414 isolates were collected from 15 participating US sites. In vitro resistance rates appeared similar to 2017 rates, with considerable resistance among staphylococci to azithromycin (52-60%), oxacillin/methicillin (30-49%), and ciprofloxacin (30-31%). CoNS isolates also exhibited resistance to trimethoprim (25%) and tobramycin (23%). Multidrug resistance (MDR; resistance to ≥3 antibiotic classes) was observed in 30% of S. aureus and 40% of CoNS, with MDR especially prevalent among methicillin-resistant staphylococci (72-77%). Isolates of S. pneumoniae were resistant to azithromycin (33%) and oral penicillin (28%) with no resistance to fluoroquinolones. All isolates of P. aeruginosa were susceptible to fluoroquinolones, with 6% exhibiting resistance to polymyxin B. With the exception of a single tetracycline-resistant isolate, all H. influenzae were susceptible to tested drugs.
Conclusions :
Preliminary 2018 ARMOR surveillance data highlight the continued substantial antibiotic resistance among staphylococci, especially among MR strains, with many isolates demonstrating MDR. These data should be considered before initiating empiric treatment of common eye infections.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.