Seven-Year Surveillance of North American Pediatric Group A Streptococcal Pharyngitis Isolates

June 21, 2009 at 8:15 pm Leave a comment

Clinical Infectious Diseases  July 1, 2009  V.49  N.1  p.78–84

Stanford T. Shulman,1,3 Robert R Tanz,2,3 James B. Dale,4,5 Bernard Beall,6 William Kabat,1

Kathleen Kabat,1 Emily Cederlund,1 Devendra Patel,1 Jason Rippe,1 Zhongya Li,6 Varja Sakota,6 and the North American Streptococcal Pharyngitis Surveillance Groupa

Divisions of 1Infectious Diseases and 2General Academic Pediatrics, Children’s Memorial Hospital, and 3Department of Pediatrics, Northwestern University, Feinberg School of Medicine, Chicago, Illinois; Departments of 4Medicine and 5Molecular Sciences, University of Tennessee Health Science Center and VA Medical Center, Memphis; and 6Centers for Disease Control and Prevention, Respiratory Diseases Branch, Atlanta, Georgia

Background. Pharyngeal group A streptococcal (GAS) emm type surveillance enhances understanding of the epidemiology of pharyngitis and invasive GAS disease and formulation of multivalent type-specific vaccines. In addition, such surveillance provides pre-GAS vaccine baseline data. We assessed geographic and temporal trends in GAS emm-type distribution among pediatric pharyngeal isolates collected systematically in the United States and Canada from 2000 to 2007.

Methods. We collected 100 acute GAS pharyngitis isolates from each of 13 widely scattered sites (10 in the United States and 3 in Canada) annually for 7 seasons (2000–2007) from 3- to 18-year-old children. We assessed emm type and subtype by DNA sequencing and analyzed temporal and geographic trends.

Results. A total of 7040 US and 1434 Canadian GAS isolates were studied. The 6 most prevalent emm types (in descending order) were 1, 12, 28, 4, 3, and 2 in the United States and 12, 1, 28, 4, 3, 2, and 77 in Canada, constituting 70%–71% of isolates in each country; 10 emm types constituted 87%–89% total. Fifty-six emm types were identified in the United States, including 8 new types, and 33 types in Canada. Although a few types predominated nationally, marked variability among individual sites and at individual sites from year to year was observed. US-Canadian differences in type distribution were apparent. Twenty percent of isolates represented emm subtypes that differed slightly from reference types; 110 new subtypes were identified. An experimental 26-valent M protein vaccine covers 85% of pharyngitis isolates.

Conclusions. Although overall US and Canadian emm type distribution was consistent and relatively few types dominated nationally, striking intersite and temporal variations within individual sites in prevalent emm types of GAS occurred. These results have important implications for the development and formulation of type-specific GAS vaccines.


Entry filed under: Antimicrobianos, Bacterias, Epidemiología, Infecciones oro-faríngeas.

Changing Epidemiology of Invasive Pneumococcal Disease in Canada, 1998–2007: Update from the Calgary-Area Streptococcus pneumoniae Research (CASPER) Study Increasing Burden of Invasive Group B Streptococcal Disease in Nonpregnant Adults, 1990–2007

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