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

Abstract

Group A streptococcus (GAS) is an important cause of morbidity and mortality worldwide. Surveillance of emm types has important implications, as it can provide baseline information for possible implementation of vaccination. A total of 1,349 GAS pediatric isolates were collected during a 7-year period (2007 to 2013); emm typing was completed for 1,282 pharyngeal (84%) or nonpharyngeal (16%) isolates, and emm clusters and temporal changes were analyzed. Thirty-five different emm types, including 14 subtypes, were identified. The most prevalent emm types identified were 1 (16.7%), 12 (13.6%), 77 (10.9%), 4 (10.8%), 28 (10.4%), 6 (6.8%), 3 (6.6%), and 89 (6.6%), accounting for 82.3% of total isolates. Rheumatogenic emm types comprised 16.3% of total isolates. The emm types 12, 4, and 77 were more prevalent among pharyngeal isolates, and the emm types 1, 89, 6, 75, and 11 were more prevalent among nonpharyngeal isolates. The emm types identified belonged to 13 emm clusters, and the 8 most prevalent clusters comprised 97% of all isolates. There were statistically significant decreases in the prevalence of emm types 12, 4, 5, and 61 and increases in the prevalence of emm types 89, 75, and 11, compared with the period 2001 to 2006. The proposed 30-valent GAS vaccine, which is currently in preclinical studies, encompasses 97.2% of the emm types detected in our study and 97.4% of the erythromycin-resistant strains. In addition, it includes 93.3% of the emm types involved in bacteremia. A much greater diversity of GAS emm types was identified in our area than described previously. Seasonal fluctuations and the introduction of new emm types were observed. Continuous surveillance of emm types is needed in order to evaluate the possible benefits of an M protein-based GAS vaccine. Streptococcus pyogenes (group A streptococcus [GAS]) is an important cause of morbidity and mortality worldwide (1). GAS causes a broad spectrum of diseases, ranging from mild to lifethreatening invasive infections. GAS infections can also lead to immune-mediated sequelae such as rheumatic fever and glomerulonephritis, with long-term complications (2, 3).In order to yield such a diversity of clinical manifestations, GAS possesses a large number of virulence mechanisms, with a high degree of variability in virulence determinants among different GAS serotypes (4, 5). The cell wall-associated M protein, encoded by the emm gene, is a major antigenic epitope and virulence factor of GAS and forms the basis for the serotyping of GAS isolates (6). The M protein acts as an epithelial adhesion factor, inhibits phagocytosis, and allows the organism to overcome innate immune responses (7,8). The N terminus consists of a highly variable amino acid sequence, resulting in antigenic diversity, and is the basis for a nucleotide-based emm-typing scheme (9). There are at least 220 different emm types and subtypes of GAS, and new types are still being identified (8,10,11). Temporal, geographic, and seasonal variations in the dominant strains are well described and can ...

Reassessment of the Role of Rapid Antigen Detection Tests in Diagnosis of Invasive Group A Streptococcal Infections

“…Nonetheless, the increased prevalence of emm type 28 strains was not observed in our study. emm type 12 strains were isolated exclusively from children, which correlated with literature data that showed a predominance of emm types 1 and 12 in pediatric invasive infections (21,22). Finally, GAS strains detected from respiratory and osteoarticular samples were predominantly emm type 1.…”

Circulating emm types of Streptococcus pyogenes in Scotland: 2011–2015

“…There are over 200 recorded emm types and subtypes that help in the identification of outbreaks and cluster management (CDC, 2008). In Scotland, between 1999 and 2005, there was a rise in invasive GAS infections from 50 to 200 per year (HPS Weekly Report, 2006), a finding consistent with observations from other European countries (Luca-Harari et al, 2009;Koutouzi et al, 2015). This study reports on the distribution of GAS emm types and subtypes from invasive and non-invasive sites over a 4-year period and further identifies the most susceptible age/sex range for invasive disease.…”

Detection of Group A Beta Hemolytic Streptococci Species, emm, and Exotoxin Genes Isolated from Patients with Tonsillopharyngitis

“…In the pharyngitis emm12 (15.7%), emm1 (15.6%), emm4 (11.8%), emm77 (11.7%), emm28 (10.7%), emm3 (6.8%); and in the tonsillitis emm3 (18.2%), emm89 (13.6%), emm1, emm2, emm28, and emm4 types were detected. It has been reported that the recommended 30-valent GAS vaccine covers 97.2% of these emm types [28]. 7 of the 10 different emm types (emm1, emm5, emm14, emm18, emm19, emm29, and emm89) were detected in the 26-valent vaccine and the coverage rate was 50% [3].…”