Related Experiment Video
Updated: Oct 1, 2025
Bile Salt-induced Biofilm Formation in Enteric Pathogens: Techniques for Identification and Quantification
Published on: May 6, 2018
Consistent Biofilm Formation by Streptococcus pyogenes emm 1 Isolated From Patients With Necrotizing Soft Tissue
Dag Harald Skutlaberg1,2, Harald G Wiker1,2, Haima Mylvaganam2
1Department of Clinical Science, University of Bergen, Bergen, Norway.
Objectives:
Biofilm 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.
Methods:
Bacterial 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.
Results:
Among 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.
Conclusions:
The 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.
Insights
Streptococcus pyogenes emm1 isolates uniformly form biofilms, unlike other strains. The clinical impact of biofilm formation in necrotizing soft tissue infections remains unclear.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Biology
Background:
- Biofilm formation is observed in Streptococcus pyogenes (necrotizing soft tissue infection) infections.
- The role of M-protein in S. pyogenes biofilm formation is established, but emm type associations are inconsistent.
- Clinical significance of S. pyogenes biofilms in necrotizing soft tissue infection (NSTI) requires further investigation.
Purpose of the Study:
- Characterize biofilm-forming capacity of S. pyogenes isolates from NSTI patients.
- Correlate biofilm formation with emm types and patient clinical characteristics.
- Investigate the specific biofilm-forming behavior of emm1 isolates.
Main Methods:
- Prospective observational study of 57 NSTI patients.
- Collection of bacterial isolates and clinical data.
- Microtiter plate assay to quantify biofilm-forming capacity.
Main Results:
- emm1 isolates (22/57) showed uniform biofilm formation, distinct from other emm types (n=35).
- emm1 isolates exhibited a narrow-ranged, normal distribution of biofilm capacity.
- No significant association found between biofilm capacity and patient clinical features.
Conclusions:
- emm1 isolates of S. pyogenes possess a distinct and uniform biofilm-forming capacity.
- The clinical relevance of biofilm formation in S. pyogenes-associated NSTI remains to be determined.
- Further research is needed to elucidate the precise role of biofilms in NSTI pathogenesis.
