Antibiotic resistance of bacterial pathogens isolated from the conjunctiva in the Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) surveillance study (2009–2021)

Abstract

Antibiotic resistance in bacterial ocular infections is of significant clinical concern and may affect treatment outcomes. We report on in vitro antibiotic susceptibility rates and trends among conjunctival-sourced isolates collected in the Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) surveillance study. A total of 2214 conjunctival isolates (918 Staphylococcus aureus, 589 coagulase-negative staphylococci [CoNS], 194 Streptococcus pneumoniae, 171 Pseudomonas aeruginosa, and 342 Haemophilus influenzae) obtained between 2009–2021 were analyzed. Staphylococci were commonly resistant to azithromycin (≥54.8%) and oxacillin (≥29.3%). Resistance among S. pneumoniae isolates was notable for azithromycin (34.0%) and penicillin (28.9%), while P. aeruginosa and H. influenzae isolates were highly susceptible to most tested antibiotics. Methicillin-resistant staphylococci demonstrated greater concurrent resistance to other antibiotics than methicillin-susceptible isolates and exhibited high rates of multidrug resistance (≥74.0%). Among staphylococci, antibiotic resistance increased with patient age, and there were small decreases in resistance to several drugs over the 13-year period. These findings indicate that resistance to antibiotics routinely used in ophthalmic practice remains high among conjunctival isolates.