High Resolution Analysis of Biofilm Formation on Human Tendon Using Transmission Electron Microscopy
Wayne Reizner, MD, MBA1; Bowen Qiu, MD2; Irvin Oh, MD1; Karen L. de Mesy Bentley, MS1; Constantinos Ketonis, MD, PhD2
1University of Rochester, Rochester, NY; 2University of Rochester Medical Center, Rochester, NY
In a previous cadaveric model, Staphylococcus aureus was found to readily form biofilm on human tendon. Based on this evidence, it was postulated that bacteria can colonize human tendon and form biofilm in vivo in the setting of infection such as pyogenic flexor tenosynovitis [PFT].
Human tendons were isolated from patients undergoing lower limb amputation secondary to infection. Transmission electron microscopy (TEM) was used to study colonization and bacteria-tendon relationships. Tendon specimens were fixed in 2.5% glutaraldehyde/4% paraformaldehye, post-fixed in 1.0% osmium tetroxide, embedded into EPON/Araldite, polymerized and sectioned at 70nm onto grids. The grids were examined using a Hitachi 7650 TEM with an attached Gatan 11 megapixel digital camera.
TEM of procured human infected tendons revealed a diverse polymicrobial biofilm on the surface and deep within tendon ultrastructure. On the external portion of the tendon a large polymicrobial biofilm was present and composed of single cocci or pairs with occasional chain formation. Deep within the tendon, small clusters of cocci and occasional rod-shaped bacteria were observed between parallel bundles of collagen fibrils
This study provides in vivo human evidence that bacterial biofilm readily forms on human tendon as verified through the use of high magnification TEM. In multiple fields, biofilm research has transformed the understanding of infection pathophysiology and redefined management strategies of infection, such as in prosthetic joint infections. This analysis of in vivo biofilm formation in human tendon strengthens the need for future research on optimizing PFT treatment protocols aimed at prevention of tendon colonization and management of biofilm formation.
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