Consistent Biofilm Formation by Isolated From Patients With Necrotizing Soft Tissue Infections.

Objectives: Biofilm formation has been demonstrated in muscle and soft tissue samples from patients with necrotizing soft tissue infection (NSTI) caused by , but the clinical importance of this observation is not clear. Although M-protein has been shown to be important for biofilm formation in , the evidence for an association between type and biofilm forming capacity is conflicting. Here we characterize the biofilm forming capacity in a collection of isolates causing NSTI, and relate this to 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 types were ( = 22), ( = 13), and ( = 7). The distribution of biofilm forming capacity in was qualitatively (narrow-ranged normal distribution) and quantitatively (21/22 isolates in the intermediate range) different from other types (wide ranged, multimodal distribution with 5/35 isolates in the same range as ). There were no significant associations between biofilm forming capacity and clinical characteristics of the patients.

Conclusions: The biofilm forming capacity of isolates was uniform and differed significantly from other types. The impact of biofilm formation in NSTI caused by on clinical outcomes remains uncertain.