High virulence gene diversity in Streptococcus pyogenes isolated in Central Italy.

Daniela Bencardino,Maria Chiara Di Luca,Dezemona Petrelli,Luca Agostino Vitali,Manuela Prenna

doi:10.7717/peerj.6613

Abstract

Globally, Streptococcus pyogenes poses a continuous burden on human health, causing both self-limiting and life-threatening diseases. Therefore, studying the profile of virulence genes and their combinations is essential to monitor the epidemiology and pathogenic potential of this important species. Thus, the aim of this study was to analyze related genetic features of clinical strains collected in Italy in 2012 in order to obtain a valid picture of their virulence profile that could be compared to similar studies made in other countries approximately in the same period. We conducted emm typing and fibronectin-collagen-T antigen (FCT) region typing in 122 Streptococcus pyogenes strains. Furthermore, several additional virulence genes were screened by polymerase chain reaction. We found correlations between emm types and FCT region profiles. emm1 strains were mainly associated with FCT2 and FCT6, while emm89 and emm12 strains were associated with FCT4. FCT5 was mainly represented in emm4, emm6, and emm75 strains. Significantly, we defined subtypes for each FCT type based on the differences in single and double loci compared to the reference scheme used for the classification of the FCT region. In addition, new FCT-region variants with differences in multiple loci were also recorded. Cluster analysis based on virulence gene profiling showed a non-random distribution within each emm type. This study added new data to existing studies conducted worldwide and revealed new variability scores in circulating Streptococcus pyogenes strains and new assortments in well-established virulence gene signatures.

Highlights

Streptococcus pyogenes is an important human pathogen that colonizes the pharynx and the skin, causing an array of diseases ranging from mild sore throat and impetigo to invasive and life-threatening infections (Cunningham, 2000).Like most pathogens, GAS produces many virulence factors (Cunningham, 2000)
High virulence gene diversity in Streptococcus pyogenes isolated in Central Italy
We detected a consistent heterogeneity of non-fibronectin-collagen-T antigen (FCT) virulence genes across all emm types (Fig. 2), we considered their distribution in the most prevalent emm types, namely emm1, emm4, emm89, emm6, emm12, and emm29 (Table 2; Fig. 2—labels with a larger font size). speB was detected in all strains

Summary

Introduction

Streptococcus pyogenes (group A Streptococcus, GAS) is an important human pathogen that colonizes the pharynx and the skin, causing an array of diseases ranging from mild sore throat and impetigo to invasive and life-threatening infections (Cunningham, 2000). GAS produces many virulence factors (Cunningham, 2000). Eleven virulence factors have been identified as superantigens: three chromosomally encoded genes (speG, speJ, and smeZ) and eight genes harbored by temperate phages (speA, speC, speH, speI, speK, speL, speM, and ssa) (Friães et al, 2013). How to cite this article Bencardino D, Di Luca MC, Petrelli D, Prenna M, Vitali LA. High virulence gene diversity in Streptococcus pyogenes isolated in Central Italy.

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