Oral Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

A serological evaluation of the host immune response during Necrotizing Soft Tissue Infections caused by Streptococcus pyogenes (#15)

Anshu Babbar 1 , INFECT Study Group 1 , Dietmar H. Pieper 1 , Andreas Itzek 1
  1. MINP, Helmholtz Center for Infection Research, Braunschweig, LOWER SAXONY, Germany

Background:  Necrotizing Soft Tissue Infection (NSTI) is a fulminant disease of the deeper layers of skin and subcutaneous tissue mainly caused by Streptococcus pyogenes. It was hypothesized that a lack of protective antibodies against the causative bacterial pathogen and its specific spectrum of secreted toxins represents a risk factor towards the development of severe NSTI.

Methods: A serologic approach was pursued using plasma samples (Day 0 and 3) and bacterial isolates of clinical NSTI cases and non NSTI control cases. The antibody mediated protection potential of the plasma samples against the corresponding bacterial pathogens and its specific exotoxin sets identified by a multiplex PCR screening was measured by an established Opsono-Phagocytosis assay and ELISA system along with specialized functional assays respectively.

Results: The adaptive immune system of analyzed NSTI patients was unable to provide efficient protection against the corresponding bacterial isolate during the early stage of infection, although an applied IVIG treatment was able to compensate this susceptibility. In contrast, the plasma samples of non NSTI control cases possessed specific antibodies against the bacteria and its exotoxins that mediated effective opsonization, bacterial killing and toxin neutralization.

Conclusion: A lack of protective antibodies against the invading bacterial pathogen and its specific set of secreted toxins represent a significant risk factor for the development of a severe NSTI. Additionally, it could be shown that the applied IVIG treatment is able to compensate this serologic susceptibility.