Monitoring antibiotic resistance in ocular microorganisms: results from the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) 2009 surveillance study

Abstract

Purpose: To determine the antibacterial susceptibility profile of bacterial pathogens from ocular infections against relevant aminoglycoside, β-lactam, cephalosporin, chloramphenicol, fluoroquinolone, glycopeptide, lincosamide, and macrolide antibacterial agents.

Design: Laboratory investigation.

Methods: Isolates from patients with bacterial eye infections were collected prospectively by 34 institutions across the United States and were submitted to a central laboratory for inclusion in the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) study. Minimum inhibitory concentrations were determined by microbroth dilution for 200 Staphylococcus aureus (S. aureus), 144 coagulase-negative staphylococci, 75 Streptococcus pneumoniae (S. pneumoniae), 73 Haemophilus influenzae (H. influenzae), and 100 Pseudomonas aeruginosa (P. aeruginosa) isolates.

Results: A large proportion of S. aureus and coagulase-negative staphylococci isolates were resistant to oxacillin/methicillin, azithromycin, or fluoroquinolones; 46.5% of S. aureus, 58.3% of coagulase-negative staphylococci, 9.0% of P. aeruginosa, and 9.3% of pneumococcal isolates were nonsusceptible to 2 or more antibacterial drug classes. Only 2.7% of H. influenzae isolates were nonsusceptible to 1 of the agents tested. Methicillin-resistant staphylococci were statistically more likely (all P < .0038) also to be resistant to fluoroquinolones, aminoglycosides, and macrolides.

Conclusions: Resistance to 1 or more antibiotics is prevalent among ocular bacterial pathogens. Current resistance trends should be considered before initiating empiric treatment of common eye infections.