Review Question - QID 4640

Exopolysaccharide glycocalyx allows bacteria to adhere to orthopaedic implants and elude antimicrobial therapies through the creation of biofilms.

Biofilms are defined as a structured community of bacterial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living surface. Biofilm production usually occurs within 4 weeks, and is extraordinarily hard to eradicate with antibiotic therapy alone. In the setting of a chronic infection of an orthopaedic implant (>4 weeks), explantation of the implant followed by antimicrobial therapy is the most reliable method of curing the infection.

Nguyen et al. reviewed 21 patients who underwent revision arthroplasty with negative intraoperative cultures. After standard cultures were obtained (all negative), the implants underwent an ultrasound protocol to theoretically disrupt the biofilm. 1 of the 21 implants grew coag-negative Staph after the bath.

Fux et al. reviewed biofilms with respect to orthopaedic and non-orthopaedic conditions. They discussed how aspirations are often falsely negative possibly because the microorganisms persist only within a biofilm on the synovia but not in planktonic form.

Illustration A and the video provided show the process of biofilm formation.

Incorrect Answers:
Answer 1: Osteoclast differentiation relies on the RANK-RANKL signaling pathway.
Answer 3: Osteolytic bone lesions are also caused by the RANK-RANKL pathway.
Answer 4: Endochondral bone formation occurs when osteoblasts lay down bone on a cartilaginous framework. Exopolysaccharide glycocalyx does not play a role in this.
Answer 5: Intramembranous bone formation does not involve exopolysaccharide glycocalyx.