Host Proteins Determine MRSA Biofilm Structure and Integrity

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Human extracellular matrix (hECM) proteins aids the initial attachment and initiation of an infection, by specific binding to bacterial cell surface proteins. However, the importance of hECM proteins in structure, integrity and antibiotic resilience of a biofilm is unknown. This study aims to determine how specific hECM proteins affect S. aureus USA300 JE2 biofilms.

Biofilms were grown in the presence of synovial fluid from rheumatoid arteritis patients to mimic in vivo conditions, where bacteria incorporate hECM proteins into the biofilm matrix. Difference in biofilm structure, with and without addition of hECM to growth media, was visualized by confocal laser scanning microscopy. Two enzymatic degradation experiments were used to study biofilm matrix composition and importance of hECM proteins: enzymatic removal of specific hECM proteins from growth media, before biofilm formation, and enzymatic treatment of 24-hour-old biofilms.

hECM addition changed the overall biofilm structure, with larger dispersion of cells within the biofilm matrix. Fibrin, elastin, and collagen were important in forming and maintaining the biofilm structure. Their absence, from growth media, reduced biofilm formation 5-fold, indicating that they are important for biofilm initiation. Their enzymatic degradation, in an established biofilm, caused dispersal, showing that these proteins are critical for structural integrity. A combination of antibiotics with hECM degrading enzymes did not improve the treatment outcome.

We conclude that while hECM proteins are an integral part of the biofilm matrix, we find no evidence that these matrix components are directly responsible for the biofilm’s unique antibiotic resilience. The hECM proteins are however highly important in determining biofilm structure and initiation. When utilizing in vitro biofilm models, we therefore recommend addition of hECM proteins to standard growth media, in order to mimic biofilm properties and structure seen in vivo.
Original languageEnglish
Publication year2017
Publication statusPublished - 2017
EventEurobiofilms 2017: 5th European Congress on Microbial Biofilms - Amsterdam, Netherlands
Duration: 19 Sep 201722 Sep 2017


ConferenceEurobiofilms 2017
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  • Eurobiofilms 2017

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