Abstract
Purpose: :
Ocular TRUST (Tracking Resistance in the US Today) is the only nationwide antimicrobial susceptibility surveillance program specific to isolates from ocular infections. Longitudinal data for 2006-2009 are presented.
Methods: :
Geographically distributed eye centers and community hospitals submitted samples from ocular infections requiring antimicrobial culturing. Isolates were tested by broth microdilution according to CLSI methodology at a centralized independent laboratory. The antimicrobial panel included azithromycin (AZI), polymyxin B (PLX), tobramycin (TOB), trimethoprim (TMP), and the fluoroquinolones (FQs) ciprofloxacin (CIP), gatifloxacin (GAT), levofloxacin (LEV), and moxifloxacin (MOX). Penicillin and oxacillin were included as controls. MICs were interpreted as susceptible, intermediate, or resistant according to CLSI criteria. Staphylococci were evaluated in terms of methicillin susceptibility (MS)/resistant (MR) phenotype.
Results: :
696 Staphylococcus aureus isolates (2006-2009) and 268 coagulase-negative staphylococci (2007-2009) were submitted for testing. In 2007-2009 surveillance, 38-54% of S. aureus isolates and 57-68% of coagulase negative staphylococci were MR phenotype. TMP was the most consistently active agent against staphylococci, regardless of methicillin phenotype, with susceptibility rates of >98% in MSSA and >93% in MRSA. TOB and TMP shared similar activities in coagulase-negative staphylococci, regardless of methicillin phenotype, but TOB susceptibility rates were <55% in MRSA. Susceptibility profiles for FQs were virtually identical and varied according to methicillin phenotype: MRSA, 80%. All antimicrobials tested displayed year-to-year fluctuations in susceptibility rates but with no trends indicating increased antimicrobial resistance over time in pathogens tested.
Conclusions: :
Antimicrobial susceptibility patterns have been relatively stable over the surveillance period. While FQs have displayed nearly identical susceptibility profiles, susceptibility rates favored TMP in staphylococci infections requiring culturing.
Keywords: antigen presentation/processing • strabismus • clinical (human) or epidemiologic studies: systems/equipment/techniques