Bactericidal activity of antimicrobial coated polyurethane sleeves for external fixation pins

Abstract

This study was conducted to assess the potential of gentamicin coated polyurethane sleeves to inhibit bacterial colonization on external fixation pins and wires. These antimicrobial sleeves have been designed to be fitted over the pins and wires, at the time of surgery, as a prophylactic approach to combat the major complication of external fixation treatment, pin tract infection. Elution testing was conducted to estimate the amount of gentamicin released into the pin tract. These gentamicin concentrations were compared to the gentamicin minimal inhibitory concentration (MIC) level for common pin tract pathogens. Elution testing revealed that the gentamicin coated polyurethane sleeves released significant quantities of the antibiotic for up to 26 weeks. The initial bolus release was characterized by predicted pin tract gentamicin concentrations of >SO pg/ml at the 2 h and 1 day elution time points. These amounts of gentamicin, delivered directly to the pin tract, are far beyond those that could be achieved via oral or intravenous administration. Furthermore, the expected concentration of gentamicin in the pin tract remained above the National Committee for Clinical Laboratory Standards (NCCLS) MIC breakpoint of 4 pglml, [Performance standards for antimicrobial susceptibility testing: twelfth informational supplement M100-SI2, NCCLS, Wayne, PA, 20021, for at least 20 weeks. Data from the SENTRY antimicrobial surveillance program (1997)(1998)(1999)(2000)(2001)(2002)) established a high level of bactericidal activity for gentamicin, with 83.1% of the common pin tract pathogen isolates found to be susceptible to the antibiotic. The initial burst and subsequent long-term sustained local delivery of effective amounts of gentamicin from the antimicrobial sleeves would be expected to inhibit bacterial colonization on external fixation pins and wires. This inhibition of bacterial colonization should substantially reduce the incidence of pin tract infection, and improve the overall outcome and cost effectiveness of external fixation fracture management.

Bacteria and cell cytocompatibility studies on coated medical grade titanium surfaces

“…These coatings successfully decreased the amount of bacteria surrounding the coated surfaces. Forster et al 16 found that using gentamicin-coated PU sleeves over external fixation pins inhibited bacterial colonization. Release kinetic experiments for these coatings showed an initial burst release, followed by a constant antibiotic release at a level above the minimal inhibitory concentration (MIC) for the antibiotics used.…”

“…Release kinetic experiments for these coatings showed an initial burst release, followed by a constant antibiotic release at a level above the minimal inhibitory concentration (MIC) for the antibiotics used. [13][14][15][16] MIC values are useful, but the bactericidal activity in vivo is unpredictable due to host reactions. For example, in vitro methicillin resistant S. aureus (MRSA) and methicillin susceptible S. aureus (MSSA) are susceptible to a variety of antibiotics; however, in vivo MRSA and MSSA bacteria are less susceptible and show resistance to the antibiotics.…”

Drug Eluting Stents Coated With Rapamycin Crystals for the Prevention of Restenosis and Biofilm Formation

“…Forster et al 31 in their study carried out to assess the potential of gentamicin coated polyurethane sleeves to inhibit bacterial colonization on external fixation pins and wires. The initial burst release was characterized by predicted pin tract gentamicin concentrations of >80 µg/ml at the 2 h and 1day elution time points.…”

Prevention of pin tract infection with iodine-supported titanium pins

“…They reported on the techniques, including loading the nanotubes with the antibiotic gentamicin. Another report described prevention of pin tract infection by fitting gentamicincoated sleeves over the pins [21]. These studies were basic research and not clinical trials.…”