Abstract
Purpose: :
Community acquired MRSA (CA–MRSA) infections have presented as toxic soft skin infections and necrotizing pneumonia. Outbreaks have occurred among children in daycare, athletes and prisoners. The origin of these unique strains of MRSA is still being debate. They differ from healthcare or nosocomial isolates by their drug resistant profile, presence of PVL gene and site of infections. Staphylococcus aureus remains the most frequently recovered ocular pathogen. Our goal was to 1) determine the prevalence of CA–MRSA profiles among ocular isolates and 2) to evaluate the in vitro susceptibilities of two new antimicrobials daptomycin (a lipopeptide) and tigecycline (a glycycline) against our ocular MRSA isolates.
Methods: :
Ocular MRSA isolates recovered from conjunctiva (103) lids (24), cornea (74) and intraocular fluids (14) during the 6 year period (2000–November 2005) were characterized by their drug resistance patterns as community–acquired (CA–MRSA–resistant to methicillin and 1 other antibiotic class, with no or minimal exposure to healthcare) or health care associated (HA–MRSA–resistant to methicillin and 3 or more antibiotic classes with a history of exposure to healthcare). In vitro susceptibilities (N=40) were determined for daptomycin and tigecycline and compared against common ocular antibiotics (erythromycin, bacitracin, tetracycline, trimethoprim–sulfa, gentamicin, ciprofloxacin, moxifloxacin and gatifloxacin).
Results: :
MRSA rates ranged from 27.3% for lids (24/88) to 60% for vitreous (12/20). The rate for cornea was 34.9%, 74/212. CA–MRSA profiles were detected in 62.5% (15/24), of lid isolates, 14.6% (15/103) of conjunctival isolates and 4.0% (3/74) of corneal isolates. In vitro susceptibility in descending order: daptomycin (97%), tigecycline (95%), gentamicin (95%), trimethoprim sulfa (87%), gatifloxacin (60%), moxifloxacin (60%), levofloxacin (57%), ciprofloxacin (55%) and bacitracin (37%) and erythromycin (37%).
Conclusions: :
. The majority of ocular MRSA isolates are associated with prior antibiotic exposure or other medical interventions. Conjunctiva and lids may serve as reservoirs for CA–MRSA. Daptomycin and Tigecycline could offer alternative treatment for management of ocular MRSA isolates.
Keywords: antibiotics/antifungals/antiparasitics • bacterial disease • clinical laboratory testing