Emergence of New CMRSA7/USA400 Methicillin-Resistant Staphylococcus aureus spa Types in Alberta, Canada, from 2005 to 2012

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most significant pathogens affecting global public health and health care systems. In Canada and the United States, the spread of MRSA is primarily attributed to a single dominant epidemic clone: CMRSA10/USA300. Despite this, the CMRSA7/USA400 epidemic clone has been reported to be the predominate epidemic clone in several Canadian provinces and some parts of the United States. This study examined the epidemiology of CMRSA7/USA400 MRSA in Alberta, Canada, from June 2005 to December 2012. Molecular characterization of CMRSA7/USA400 isolates was done using spa , SCC mec , PVL, and PFGE typing and identified two predominant spa types in Alberta: t128 and t1787. Although closely related, these spa types have distinct geographic distributions. From 2010 to 2012, the number of t128 infections has remained stable while there has been a nearly 3-fold increase in the number of provincial t1787 infections, accompanied by 10-fold increases in t1787 infection rates in some communities. Most t128 and t1787 patients were First Nations or Inuit people, and isolates were usually from skin and soft tissue infections in outpatients. t128 patients were significantly older than t1787 patients. Antimicrobial susceptibility testing showed higher mupirocin resistance in t1787 than in t128 MRSA. Improved strategies to reduce or stabilize t1787 infections in Alberta are needed.

The Prevalence, Risk, and Management of Methicillin-Resistant Staphylococcus aureus Infection in Diverse Populations across Canada: A Systematic Review

“…Although the general trend found reports of increasing prevalence over time, a small number of studies reported lower MRSA prevalence rates. Li et al [ 21 ] reported a MRSA prevalence of 0.32 per 100,000 Albertans in 2005, and Bracco et al [ 22 ] reported a MRSA prevalence of only 1.1% among ICU patients in Montreal from 2002 to 2004 inclusive, suggesting that there may be some site-to-site variation in the detection or prevalence of MRSA.…”

Subinhibitory concentrations of resveratrol reduce alpha-hemolysin production in Staphylococcus aureus isolates by downregulating saeRS

“…The USA300 strain belongs to ST8 and has a high prevalence and morbidity rate over a period of time 21 . The MW2 (USA400) epidemic clone has also been the predominant epidemic clone in several Canadian provinces and some parts of the United States 22 . SA759 belongs to ST239, which is a major cause of MRSA infections in Asian hospitals 23 .…”

Phenotypes and Virulence among Staphylococcus aureus USA100, USA200, USA300, USA400, and USA600 Clonal Lineages

“…These strains colonize mucosal surfaces and cause life-threatening infections, most notably menstrual TSS, which occurs in otherwise healthy women ( 13 ). USA400 strains are also community associated, are frequently isolated in the upper Midwest and southwestern Alaska, and have emerged as the predominant MRSA type in western Canada ( 14 , 15 ).…”