Biomaterial-associated infection of gentamicin-loaded PMMA beads in orthopaedic revision surgery

Abstract

In two-stage orthopaedic revision surgery, high local levels of antibiotics are achieved after removal of an infected prosthesis through temporary implantation of gentamicin-loaded beads. However, despite their antibiotic release, these beads act as a biomaterial surface to which bacteria preferentially adhere, grow and potentially develop antibiotic resistance. Gentamicin-loaded beads were retrieved from 20 patients with prosthesis-related infections. Excised tissue samples were taken for routine culture, while beads were analysed in an extensive laboratory procedure. Extensive culture procedures indicated the presence of bacteria on gentamicin-loaded beads in 18 of the 20 patients involved, while 12 of these 18 patients were considered free of infection by routine culture. Nineteen of 28 bacterial strains isolated were gentamicin resistant and cultures from three patients yielded highly gentamicin-resistant sub-populations. It is concluded that routine culture of excised tissues in orthopaedic revision surgery is inadequate to ascertain full eradication of infection, especially as infecting, antibiotic-resistant bacteria preferentially adhere to and grow on gentamicin-loaded beads. Extensive examination of the bead surfaces is proposed as a more reliable indication that infection has been eradicated.

A fully functional drug-eluting joint implant

“…In addition to the risk of mechanical failure during weight bearing, antibiotic-eluting PMMA BCs showed bacterial adhesion [50] even during antimicrobial elution [51]. On the other hand, radiation sterilized VPE significantly reduced bacterial adherence through surface-bonded vancomycin (Figure 3g and 3h).…”

Perspectives on the prevention and treatment of infection for orthopedic tissue engineering applications

“…Biofilms are capable of growing on the surface of implanted materials and have even been shown to survive on the surface of antibiotic-releasing biomaterials [52,53]. As shown in Figure 1, Staphylococcus aureus is able to form biofilm even on antibiotic-releasing poly(methyl methacrylate) constructs.…”

The role of small-colony variants in failure to diagnose and treat biofilm infections in orthopedics

“…These beads are usually removed after 2 weeks and the absence of cultivable microorganisms in excised soft tissue samples by routine hospital culture is taken as a sign that the infection has been eradicated, and implantation of a new prosthesis can take place. Although the use of gentamicin-loaded beads is accepted in clinical practice, the beads themselves can act as a biomaterial surface to which subpopulations of bacteria may preferentially adhere, grow and possibly even develop antibiotic resistance (Neut et al 2001).…”