Osteomyelitis is a common bone infection caused by bacteria or in some cases, fungus . Osteomyelitis generally occurs by infection of bacteria in several different ways, including via the bloodstream, from neighboring areas of infection, or due to non-sterile joint replacements and internal fixations such as fractures . In 90% of cases, an S. aereus bacterium is the microbial culprit responsible for osteomyelitis . In the cases of open would fractures, osteomyelitis can interfere with normal bone healing and regeneration . Symptoms of osteomyelitis include bone pain, fever, malaise, swelling, redness, chills, excessive sweating, and joint pains . It is reported that in 20% of the cases, the infection is hematogenous, or spread by the blood . The incidence of spinal osteomyelitis was reported to be 1 in 450,000 in 2001 . The incidence of vertebral osteomyelitis is reported to be 24 cases per 1,000,000 and the incidence in children is approximately 1 in 5,000 . Approximately 10-15% of people with vertebral osteomyelitis develop spinal-cord compression and approximately 30% of patients with long bone osteomyelitis develop deep vein thrombosis (DVT) . Mortality rates are generally low unless sepsis occurs . The overall incidence of osteomyelitis was found to be higher in developing countries compared to developed nations .
Current Clinical Standard of Care:
The current gold standard treatment for osteomyelitis is gentamycin or vancomycin impregnated poly methyl methacrylate (PMMA) beads . These beads are surgically implanted at the site of bacterial infection, and the antibiotic will diffuse from these beads .
Both vancomycin and gentamycin inhibit bacterial growth by different means. Vancomycin, a naturally hydrophilic drug, primarily targets gram-positive bacteria . The drug works by hydrogen bonding to two specific peptide sequences, namely N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) . Both NAM and NAG are two important peptides which form the backbone of bacterial cell walls through long polymerization . The interaction of vancomycin with these peptide sequences inhibits this polymerization and thereby inhibits bacterial cell wall formation causing bacterial cells to die .
Gentamycin, on the other hand, can be used to target both gram-positive and gram-negative bacteria . Gentamycin works by binding to the 30S subunit of the bacterial RNA. Due to this binding, protein synthesis is irreversibly inhibited and bacterial cells die as a result .
Several studies have documented the effectiveness of the antibiotic impregnated PMMA beads. For example, one study showed that in patients who suffered from bacterially infected non-unions of bone, treatment with gentamycin-impregnated PMMA beads showed similarity in infection control when it was compared to long term parenteral infusion of gentamycin . A long-term study by Duncan...