Identity and Prevalence of Multilocus Sequence Typing-Defined Clones of Group A Streptococci within a Hospital Setting

Abstract

, 121 clinical isolates of group A streptococci (GAS) were collected from a London hospital and characterized by multilocus sequence typing (MLST) to determine the identity and prevalence of clones circulating within this setting. A total of 39 sequence types (ST), of which 20 were represented by a single isolate, were identified. The eight most prevalent clones among the 121 GAS were ST117/emm81 (16%), ST39/emm4 (9%), ST62/emm87 (7%), ST28/emm1 (6%), ST36/emm12 (6%), ST46/emm22 (5%), ST334/emm82 (5%), and ST101/emm89 (4%). Compared to those in the MLST database (http://spyogenes.mlst.net), 12 (31%) of the 39 STs had not been previously identified, although 7 of these differed from recognized STs at only a single locus, suggesting they were closely related to previously recognized strains. Resistance to erythromycin and tetracycline was seen in 7 and 20% of isolates, respectively, with four isolates resistant to both agents. GAS strains with higher (>80) emm types accounted for 45% of GAS isolates collected during this study. Continuing GAS surveillance, using easily comparable methods, is important for detecting changes in the character of disease-causing isolates.

Macrolide-Resistant Streptococcus pyogenes in Norway: Population Structure and Resistance Determinants

“…Three of the CCs displayed the erm(TR)-encoded MLS B phenotype and were coresistant to tetracycline. ST46 in CC1 has been associated with erm(B), mef(A/E), or macrolide susceptibility in other countries (20,28,36), whereas ST63 in CC2 contained erm(TR) in Poland and Germany in accordance with our findings (28,36). The remaining six strains in CC2 belonged to ST369, which is a single locus variant (SLV) of ST63 not previously registered in the MLST database.…”

“…CC4 was monoresistant to macrolides due to mef(A). This clone has previously been observed in Finland, Germany, Spain, and England (14,20,26,28).…”

“…The emm types were all present in the Centers for Disease Control and Prevention database, and 31 of 44 strains (70%) had sequence types (STs) previously defined in the MLST database (Table 2) (10,20,28,36). A total of 13 strains revealed new allele combinations and were assigned to new STs (Table 3).…”

Genetic Relationships Deduced from emm and Multilocus Sequence Typing of Invasive Streptococcus dysgalactiae subsp. equisimilis and S. canis Recovered from Isolates Collected in the United States

“…M-protein gene (emm) typing has been useful as a simple genetic tool for identifying and resolving Streptococcus pyogenes strains for epidemiologic studies (18,27,29,35). This is consistent with the observation that within given regions, group A streptococcal (GAS) emm types are often restricted to only one or two defined clonal complexes, and often, these common clones are predominant in diverse locations (15) (available at www.mlst.net).…”

Evaluation of sclB gene variation in Streptococcus pyogenes (Lancefield group A Streptococcus) and potential for subtyping

“…GAS epidemiological investigations have benefited from MLST data; Sakota et al (2006) observed that genetic diversity amongst superficial GAS strains from Nepal was remarkably higher than that of strains from the USA, aiding the delineation of GAS clones and elucidating their distribution in different parts of the globe. In hospital settings it can add valuable information to determine the distribution of clones and any possible change in prevalent types, which might signify the appearance of more virulent and successful clones (McGregor & Spratt, 2005). Strain characterization by MLST is sometimes combined with PFGE.…”