USA300 Methicillin-Resistant Staphylococcus aureus, United States, 2000-2013.

Margaret Carrel,Michael Z David,Eli N Perencevich

doi:10.3201/eid2111.150452

Abstract

In the United States, methicillin-resistant Staphylococcus aureus (MRSA) with the USA300 pulsed-field gel electrophoresis type causes most community-associated MRSA infections and is an increasingly common cause of health care-associated MRSA infections. USA300 probably emerged during the early 1990s. To assess the spatiotemporal diffusion of USA300 MRSA and USA100 MRSA throughout the United States, we systematically reviewed 354 articles for data on 33,543 isolates, of which 8,092 were classified as USA300 and 2,595 as USA100. Using the biomedical literature as a proxy for USA300 prevalence among genotyped MRSA samples, we found that USA300 was isolated during 2000 in several states, including California, Texas, and midwestern states. The geographic mean center of USA300 MRSA then shifted eastward from 2000 to 2013. Analyzing genotyping studies enabled us to track the emergence of a new, successful MRSA type in space and time across the country.

Highlights

In the United States, methicillin-resistant Staphylococcus aureus (MRSA) with the USA300 pulsed-field gel electrophoresis type causes most community-associated methicillin-resistant S. aureus (MRSA) infections and is an increasingly common cause of health care–associated MRSA infections
MRSA predominantly belonging to 5 clonal clusters (CC) emerged worldwide, causing the third wave of resistance in S. aureus that continued into the 21st century [2]
Among isolates with any reported anatomic site of isolation, skin and soft tissue infections accounted for 62.6% of USA300 and 19.1% of USA100 isolates in studies that reported specific years and geographic locations and 58.8% of USA300 and 7.0% of USA100 in all studies, inclusive of those not reporting state locations or study years

Summary

Introduction

In the United States, methicillin-resistant Staphylococcus aureus (MRSA) with the USA300 pulsed-field gel electrophoresis type causes most community-associated MRSA infections and is an increasingly common cause of health care–associated MRSA infections. Beginning in the late 1990s, new strain types of non– multidrug-resistant MRSA began to circulate outside the health care setting in the United States, a phenomenon seen even earlier in Australia [3] These community-associated MRSA infections, skin and soft tissue infections, became common in the United States after 2000 [4]. US reports on community-associated MRSA infections were published from Houston [18], Chicago [7,19] and elsewhere in the Midwest [20], Minnesota [21], Tennessee [22], Hawaii [23], and California [9,11] Soon after it began spreading in the community, USA300 became a common cause of infections in the health care setting as well, blurring the epidemiologic distinction between community-associated and health care–associated MRSA [24]

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Conclusion