Consistent Biofilm Formation by Streptococcus pyogenes emm 1 Isolated From Patients With Necrotizing Soft Tissue Infections.

Dag Harald Skutlaberg,Haima Mylvaganam,Steinar Skrede,Anna Norrby-Teglund,Harald G Wiker

doi:10.3389/fmicb.2022.822243

Abstract

ObjectivesBiofilm formation has been demonstrated in muscle and soft tissue samples from patients with necrotizing soft tissue infection (NSTI) caused by Streptococcus pyogenes, but the clinical importance of this observation is not clear. Although M-protein has been shown to be important for in vitro biofilm formation in S. pyogenes, the evidence for an association between emm type and biofilm forming capacity is conflicting. Here we characterize the biofilm forming capacity in a collection of S. pyogenes isolates causing NSTI, and relate this to emm type of the isolates and clinical characteristics of the patients.MethodsBacterial isolates and clinical data were obtained from NSTI patients enrolled in a multicenter prospective observational study. Biofilm forming capacity was determined using a microtiter plate assay.ResultsAmong 57 cases, the three most frequently encountered emm types were emm1 (n = 22), emm3 (n = 13), and emm28 (n = 7). The distribution of biofilm forming capacity in emm1 was qualitatively (narrow-ranged normal distribution) and quantitatively (21/22 isolates in the intermediate range) different from other emm types (wide ranged, multimodal distribution with 5/35 isolates in the same range as emm1). There were no significant associations between biofilm forming capacity and clinical characteristics of the patients.ConclusionsThe biofilm forming capacity of emm1 isolates was uniform and differed significantly from other emm types. The impact of biofilm formation in NSTI caused by S. pyogenes on clinical outcomes remains uncertain.

Highlights

Streptococcus pyogenes causes a broad spectrum of disease manifestations ranging from mild, superficial infections to life-threatening invasive diseases, as well as post-streptococcal sequelae
One-hundred-and-fourteen (28%) of 409 patients included in the INFECT study had a monomicrobial infection with S. pyogenes
Two cases were excluded because the density of bacterial inocula was repeatedly below the lower acceptance limit in the biofilm assay

Summary

Introduction

Streptococcus pyogenes causes a broad spectrum of disease manifestations ranging from mild, superficial infections to life-threatening invasive diseases, as well as post-streptococcal sequelae. This pathogen accounts for more than half a billion new cases and more than half a million deaths annually on a global scale (World Health Organization, 2005). Biofilm Formation in Streptococcus pyogenes have a reported annual incidence of around 3 per 100,000 persons in the Scandinavian countries (Darenberg et al, 2007; Luca-Harari et al, 2008; Naseer et al, 2016). Microorganisms growing within a biofilm are largely protected against the host’s immune systems and the effect of antibiotics (Kumar et al, 2017)

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