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MRSA prevalence rose during 3 years at dermatology clinic

The relative proportion of methicillin-resistant Staphylococcus aureus in the S aureus isolates increased 17% during a 3-year period at an outpatient dermatology clinic, according to study results.

Researchers analyzed 387 S aureus isolates between Jan. 1, 2005, and June 30, 2011, from adult and pediatric patients at the University of Miami Hospital outpatient dermatology clinic. Relative proportions of MRSA and methicillin-sensitive S. aureus (MSSA) and antibiotic sensitivity profiles were main outcome measures.

Data were available for 74 patients (mean age, 36.5 years), including 65 adults. The overall proportion of MRSA was 35.7%, and the overall relative proportion of MSSA was 64.3%. The relative proportion of MRSA during the last 6 months of the study was 33.3%, compared with 66.7% for MSSA. From Jan. 1, 2008, to Dec. 31, 2010, the relative proportion of MRSA (45.3%) was significantly higher than the relative proportion from Jan. 1, 2005 to Dec. 31, 2007 (28.3%; P=.001). Between 2005 and 2009, MRSA became more sensitive to ciprofloxacin. MSSA became more resistant to ciprofloxacin, clindamycin, gentamicin sulfate and trimethoprim-sulfamethoxazole during the study period.

“Consistent with national data, the relative proportion of MRSA in this outpatient dermatology clinic in Miami has risen,” the researchers reported. “It is important for physicians to obtain cultures of infected sites before administering an antibiotic and to tailor therapy to antibiogram results as soon as possible to appropriately treat MRSA or MSSA infection.

“Notably, in vitro susceptibility testing does not necessarily predict in vivo efficacy of an antibiotic, and physicians should alter therapy only if there is no clinical improvement.”