Antibiotic Resistance Among Ocular Pathogens in the United States: Five-Year Results From the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) Surveillance Study.
OBJECTIVE
The Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) study is the only ongoing nationwide antibiotic resistance surveillance program specific to ocular pathogens.


OBJECTIVE
To report resistance rates and trends among common ocular isolates collected during the first 5 years of the ARMOR study.


METHODS
This antibiotic resistance surveillance study was performed at an independent central laboratory. Clinical centers across the United States were invited to submit ocular isolates of Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa. Isolates were collected from January 1, 2009, through December 31, 2013, and analyzed from January 16 to May 15, 2015.


METHODS
Minimum inhibitory concentrations for various antibiotic classes were determined by broth microdilution according to the guidelines of the Clinical and Laboratory Standards Institute. Minimum inhibitory concentrations were interpreted as susceptible, intermediate, or resistant based on established break points.


RESULTS
A total of 3237 ocular isolates (1169 S aureus, 992 CoNS, 330 S pneumoniae, 357 H influenzae, and 389 P aeruginosa) were collected from 72 centers. Methicillin resistance was found among 493 S aureus isolates (42.2%; 95% CI, 39.3%-45.1%) and 493 CoNS isolates (49.7%; 95% CI, 46.5%-52.9%), and methicillin-resistant (MR) isolates had a high probability of concurrent resistance to fluoroquinolones, aminoglycosides, or macrolides (P < .001). Multidrug resistance to at least 3 additional antibiotic classes was found in 428 MR S aureus isolates (86.8%) and 381 MRCoNS isolates (77.3%). All staphylococcal isolates were susceptible to vancomycin. Resistance among S pneumoniae isolates was highest for azithromycin (113 isolates [34.2%]) whereas resistance among P aeruginosa and H influenzae was low against the antibiotics tested. Staphylococcal isolates from elderly patients were more likely to be MR, as were S aureus isolates obtained from the southern United States (P < .001). Methicillin resistance among staphylococci did not increase during the 5-year study period (P ≤ .22), and small decreases in resistance to ciprofloxacin among CoNS and MRCoNS and to tobramycin among CoNS (P ≤ .03) were found.


CONCLUSIONS
Methicillin resistance was prevalent among staphylococcal isolates from ocular infections, with many strains demonstrating multidrug resistance. These findings are consistent with resistance trends reported for nonocular staphylococcal isolates. Overall ocular resistance did not increase during the 5-year study period. Continued surveillance of ocular isolates provides critical information to guide selection of topical antibacterials used for empirical management of ocular infections.
Cornea Services, External Disease, and Refractive Surgery, Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York.
Penny A
PA
Asbell
Bausch & Lomb, Rochester, New York.
Christine M
CM
Sanfilippo
Eurofins Medinet, Chantilly, Virginia4currently with Micromyx, LLC, Kalamazoo, Michigan.
Christopher M
CM
Pillar
Bausch & Lomb, Rochester, New York.
Heleen H
HH
DeCory
Eurofins Medinet, Chantilly, Virginia5currently with IHMA, Inc, Schaumburg, Illinois.
Daniel F
DF
Sahm
Bausch & Lomb, Rochester, New York7currently with Actelion Clinical Research, Cherry Hill, New Jersey.
Timothy W
TW
Morris
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D015818:Eye Infections, Bacterial / Q000382:microbiology*; D005260:Female; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D014481:United States; D055815:Young Adult
D000900:Anti-Bacterial Agents