Abstract
Purpose :
Antibiotic resistance among ocular infections can complicate antibiotic selection and result in treatment failure. Resistance data from multi-center, multi-year surveillance studies can provide clinicians with information to guide empirical therapy choices. The Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) study captures in vitro data specific to common ocular pathogens and is the only nationwide surveillance study of its kind. Here, we report on preliminary findings for bacterial isolates collected to date in 2022.
Methods :
Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae from ocular infections were collected as part of ARMOR and submitted to a central laboratory for species confirmation and in vitro antibiotic susceptibility testing. Minimum inhibitory concentrations (MICs) for up to 16 antibiotics (10 drug classes) were determined using broth microdilution methodology and interpreted as per Clinical and Laboratory Standards Institute (CSLI) guidelines and breakpoints.
Results :
From January through October 2022, 397 isolates were collected. The 142 CoNS exhibited the highest resistance, with azithromycin, oxacillin/methicillin, trimethoprim, clindamycin, and tetracycline resistance observed in 60%, 37%, 28%, 27% and 22% of isolates, respectively. Among the 161 S. aureus, 46% were resistant to azithromycin, but <20% of isolates were resistant to other drugs. Multidrug resistance (MDR; resistance to ≥3 drug classes) was observed in 14% of S. aureus and 39% of CoNS, and in 59% and 88% of methicillin-resistant (MR) strains thereof, respectively. Among the 5 S. pneumoniae, 60% of isolates were resistant azithromycin, oral penicillin and tetracycline. Although all 72 P. aeruginosa isolates were resistant to polymyxin B, <5% were resistant to other drugs; no resistance was found among the 17 H. influenzae isolates.
Conclusions :
In vitro antibiotic resistance was common among staphylococci isolates collected in ARMOR 2022, with preliminary data indicating lower resistance rates among S. aureus compared to previous years. Nonetheless, a high prevalence of MDR, especially in MR strains, was observed. The clinical significance of these in vitro data is unclear without consideration of the ocular pharmacokinetics of tested antibiotics.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.