MRSA infections peaked in summer, fall

Mermel L. PloS ONE. 2011;doi:10.1371/journal.pone.0017925.

Although methicillin-resistant Staphylococcus aureus infections occur year round, significant increases were observed during the summer and fall months, according to Leonard Mermel, DO, ScM, FSHEA, FIDSA, and colleagues.

“Over the last decade at Rhode Island hospital, we’ve been noticing an increased incidence of MRSA infections…that seem to peak in the summer and fall months,” Mermel, medical director of the department of epidemiology and infection control at Rhode Island Hospital, said in a press release.

Compared with adult patients, pediatric patients had approximately 1.85-times as many community-associated MRSA infections (95% CI, 1.45-2.36; P<.0001) during the winter and spring months and 2.94-times as many hospital-associated MRSA infections (95% CI; P= .015) during the summer and fall.

The researchers assessed MRSA isolates submitted to the hospital laboratory between Jan. 2001 and March 2010. Poisson regression analysis was used to determine the number of emergency department visits and the number of community-associated and hospital-associated MRSA infections.

Adult patients had 1.14-times as many community-associated MRSA infections (95% CI, 1.01-1.29; P=.03) during the summer and fall when compared with winter and spring months. However, no differences were observed in the rate for hospital-associated MRSA infections among adult patients (95% CI, 0.89-1.12).

“This sets a foundation for other future investigations to be pressed now to really tease apart the seasonality and find exactly what the cause is, then we can deal with something to try to mitigate the risk of transmission. We’re not 100% certain of why this transmission and these infections appear to be occurring in this time of year,” Mermel said.

“One possible behavioral change to consider from our findings is to remember breaches in skin integrity, that may occur more often with summertime sports and recreational activities, should be thoroughly cleansed. Additionally, be mindful of skin lesions that may be erroneously thought of as representing ‘spider bites’ in the summer and fall as such lesions may well represent MRSA skin infections,” he told Infectious Diseases in Children. – by Ashley DeNyse

Disclosures: Dr. Mermel reports no relevant financial disclosures.

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