Abstract
Purpose :
Both Staphylococcus aureus and coagulase-negative staphylococci (CoNS; including Staphylococcus epidermidis) are implicated in staphylococcal blepharitis. Treatment options for this condition, often used in combination, include lid hygiene, topical anti-inflammatory agents, and topical and/or oral antibiotics. We examined the in vitro potency of antibacterial agents commonly prescribed in the management of blepharitis against staphylococcal isolates from ocular sources.
Methods :
Minimum inhibitory concentrations (MICs; µg/mL) were determined for 8 antibiotics (6 drug classes) against methicillin-susceptible and -resistant isolates of S. aureus (MSSA and MRSA, respectively) and S. epidermidis (MSSE and MRSE, respectively), as well as other species of CoNS with undetermined methicillin resistance status (excluding S. epidermidis) previously cultured from ocular infections. In vitro susceptibility testing was conducted at a central laboratory per Clinical and Laboratory Standards Institute broth microdilution methodology.
Results :
A total of 150 staphylococci (n=30 per grouping) were tested, and the MICs for 50% and 90% of isolates (MIC50 and MIC90) are presented in the table. MICs among all species were highest for macrolides and bacitracin. Besifloxacin exhibited lower MICs than ciprofloxacin. Against MRSA/MRSE specifically, the lowest MICs observed were for doxycycline and besifloxacin.
Conclusions :
Antibacterial agents commonly used in the treatment of blepharitis had variable in vitro activity against ocular staphylococci. Doxycycline and besifloxacin generally demonstrated greater in vitro potency (lower MICs) against all tested isolates, including methicillin-resistant strains, compared to other agents. These data should be considered when treating staphylococcal blepharitis.
This is a 2021 ARVO Annual Meeting abstract.