Seven-Year Surveillance of emm Types of Pediatric Group A Streptococcal Pharyngitis Isolates in Western Greece

Abstract

BackgroundAn experimental 26-valent M protein Group A streptococcal (GAS) vaccine has entered clinical studies. Pharyngeal GAS emm type surveillances in different areas and time-periods enhance the understanding of the epidemiology of GAS pharyngitis. Moreover, these surveillances, combined with the data on GAS invasive disease, can play a significant role in the formulation of multivalent type-specific vaccines.MethodsDuring a 7-year period (1999–2005), 2408 GAS isolates were recovered from consecutive children with pharyngitis in Western Greece. The overall macrolide resistance rate was 22.8%. Along the study period we noted a tendency towards significantly decreased rates of resistance, with the lowest rates occurring in 2002 (15.3%), 2003 (15%) and 2004 (16.7%). A random sample of isolates from each year, 338 (61.7%) of the 548 macrolide-resistant and 205 (11%) of the macrolide-susceptible, underwent molecular analysis, including emm typing.ResultsThe 543 typed isolates had 28 different emm types. A statistically significant association was found between macrolide resistance and emm4, emm22 and emm77, whereas emm1, emm3, emm6, emm12, emm87 and emm89 were associated with macrolide susceptibility. A significant yearly fluctuation was observed in emm4, emm28 and emm77. The most common macrolide-resistant GAS were emm77 isolates harboring erm(A), either alone or in combination with mef(A), emm4 carrying mef(A), emm28 possessing erm(B), emm75 carrying mef(A), emm12 harboring mef(A) and emm22 carrying erm(A). We estimated that 82.8% of the isolates belonged to emm types included in the novel 26-valent M protein vaccine. The vaccine coverage rate was determined mainly by the increased frequency of nonvaccine emm4 isolates.ConclusionsA limited number of emm types dominated among macrolide-susceptible and macrolide-resistant GAS isolates. We observed seasonal fluctuations, which were significant for emm4, emm28 and emm77. This type of data can serve as baseline information if the novel 26-valent M protein GAS vaccine is introduced into practice.

Streptococcus pyogenes emm Types and Clusters during a 7-Year Period (2007 to 2013) in Pharyngeal and Nonpharyngeal Pediatric Isolates

“…This 30-valent GAS vaccine would potentially cover almost 97.2% of the emm types detected in our study and 97.4% of the erythromycinresistant strains. This is much higher than the 80% coverage with the 26-valent vaccine estimated in previous studies (19,22).…”

“…In our study, we identified 35 different emm types and, among them, 15 emm subtypes that are much more diverse than the 18 emm types identified in our area in 2001 to 2006 (19). In a study from western Greece regarding pediatric pharyngeal isolates for the period from 1999 to 2005, 28 different emm types were recognized (22). In another study regarding invasive isolates from children and adults for the years 2003 to 2007, 31 different emm types were recognized, with predominance of emm1 (28.2%) and emm12 (8.5%) (23).…”

Susceptibility of Group AStreptococcusto Antimicrobial Agents in Northern Israel: A Surveillance Study

“…GAS isolates showed a significant decrease of resistance rates to erythromycin, clindamycin, and tetracycline. 6,12,28 Same low rates of resistance were found in additional studies on general populations in Serbia, 21 Turkey, 4 Belgium, 29 and Taiwan. 10 In southern Europe, erythromycin, clindamycin, and tetracycline resistance was shown to have been decreased during 2005 to 2012.…”

“…A wide variability in antimicrobial susceptibility of GAS to macrolides and tetracyclines has been reported in several geographical regions. 3,4,6,10,12,16,19,23,[27][28][29]32 Recent published data from Europe indicate an increase of resistance to macrolides, which is quite a common practice in our region. A nationwide study conducted in Israel during 1996 to 1999 studied 500 GAS isolates from invasive infections.…”

Changes in epidemiologic characteristics and antimicrobial resistance of Streptococcus pyogenes isolated over 10 years from Japanese children with pharyngotonsillitis

“…Many reports demonstrate that prevalent emm types tend to vary over time within a geographic area [7]. In high-income regions [8,9] such as the EU [10][11][12], most isolates belonged to certain emm types (emm1, emm12, emm28, emm3, emm4 and emm89) that differed from those prevailing in African and Pacific countries [7,13]. Additionally, emm types of GAS isolates from noninvasive infections such as pharyngotonsillitis clearly differ from those seen in invasive infections [14][15][16].…”