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Rachel Reem, Joany Van Balen, Armando Hoet, Colleen Cebulla; Phenotyping and genotyping of Staphylococcus aureus on ophthalmology clinic surfaces. Invest. Ophthalmol. Vis. Sci. 2013;54(15):894.
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Methicillin susceptible and resistant Staphylococcus aureus (MSSA and MRSA) are increasingly common pathogens in ophthalmology. Thus, identification of contaminated surfaces is necessary to establish appropriate prevention and control measures. The purpose of this study was to screen ophthalmic clinic equipment for MSSA and MRSA, to identify the most commonly contaminated surfaces, and to further genotype and phenotype such isolates to understand their epidemiology and origin.
A standardized environmental sampling method was used to screen 12 randomly selected examination rooms, pooled in sets of 3, from 2 ophthalmology clinic buildings. The surfaces sampled in each room were patient, staff and general public high contact surfaces. Sampling was performed on a quarterly basis for 1 year. Isolates were obtained and identified using standard microbiological techniques. Antimicrobial resistance profiles, SCCmec typing, USA typing and dendrogram analysis of pulsed-field gel electrophoresis (PFGE) pulsotypes were used to characterize all S. aureus isolates.
Of 112 total samples, 25 and 5 were MSSA and MRSA positive, respectively. The top 3 contaminated surfaces were doorknobs, computer keyboards, and slit lamp headrests. Molecular analysis showed high diversity between the isolates (17 distinct MSSA and 4 MRSA pulsotypes). Different surfaces in two separate rooms were contaminated with the same pulsotype at the same sampling time, suggesting possible cross-contamination. No single surface remained consistently positive with the same pulsotype over time. Three of the 5 MRSA isolates were CA-MRSA (SCCmec IV, USA300) and two were HA-MRSA (SCCmec II, USA100). Multi-drug resistance (resistant to 3 or more antimicrobial classes) was found in 4/5 MRSA isolates.
This study demonstrates that S. aureus (MSSA and MRSA) is present in the environment of a representative ophthalmology clinic setting. The high diversity of strains found indicates a constant introduction of clones over time. Doorknobs and nearby door surfaces appear to play an important role in the room-to-room spread of S. aureus; hence, it is recommended to include them in routine disinfection protocols. Nevertheless, the fact that no single surface tested positive more than once for the same pulsotype suggests that current disinfection procedures are effective in preventing the spread of this increasingly prevalent bacterium.
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