Abstract
Purpose:
Antibiotic resistance surveillance data can guide clinicians in the empiric treatment of ocular infections. Here we report the study results to date for the 2012 ARMOR (Antibiotic Resistance Monitoring in Ocular MicRoorganisms) surveillance study and compare the results to those from the previous three years.
Methods:
To date, 456 isolates of Streptococcus pneumoniae, Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Pseudomonas aeruginosa, and Haemophilus influenzae from 25 sites were subjected to antibiotic susceptibility testing. Minimum inhibitory concentrations were determined by broth microdilution for up to 16 representative antibiotics per Clinical and Laboratory Standards Institute methods. Systemic breakpoints (where available) were used to categorized isolates as susceptible or non-susceptible (intermediate and resistant).
Results:
While drug resistance among H. influenzae isolates was not observed, non-susceptibility among P. aeruginosa isolates was noted for ciprofloxacin (9.1%), imipenem (11.4%), tobramycin (4.5%), and polymyxin B (4.5%). S. pneumoniae isolates were non-susceptible to imipenem (13.1%), penicillin (4.9%), chloramphenicol (3.3%), and azithromycin (41.0%). S. aureus and CoNS isolates were non-susceptible to oxacillin/methicillin (37.3-41.9%), ciprofloxacin (33.8-36.6%), clindamycin (18.3-31.3%), azithromycin (58.8-60.1%), and other antibiotics. More than 33% of S. aureus and CoNS isolates were resistant to 3 or more antibiotics. Methicillin-resistant isolates of S. aureus (MRSA) and CoNS (MRCoNS) were predominantly multi-drug resistant (>73%). Compared to the three previous years, non-susceptibility rates were similar and the new data set reduced some of the fluctuation seen over the previous years.
Conclusions:
After accounting for annual fluctuations, overall resistance rates generally did not show substantial changes over the four year study period. However, a number of isolates were resistant to commonly used ophthalmic antibiotics. Multi-drug resistance was especially prevalent among the MRSA and MRCoNS isolates. Therefore, continued vigilance is warranted to monitor the contribution of resistant isolates to the pathogen population.
Keywords: 463 clinical (human) or epidemiologic studies: prevalence/incidence •
433 bacterial disease •
422 antibiotics/antifungals/antiparasitics