In Vitro Activity of Gentamicin-Loaded Bioabsorbable Beads against Different Microorganisms

Recent advances in the local antibiotics delivery systems for management of osteomyelitis

Chronic osteomyelitis is a challenging disease due to its serious rates of mortality and morbidity while the currently available treatment strategies are suboptimal. In contrast to the adopted systemic treatment approaches after surgical debridement in chronic osteomyelitis, local drug delivery systems are receiving great attention in the recent decades. Local drug delivery systems using special carriers have the pros of enhancing the feasibility of penetration of antimicrobial agents to bone tissues, providing sustained release and localized concentrations of the antimicrobial agents in the infected area while avoiding the systemic side effects and toxicity. Most important, the incorporation of osteoinductive and osteoconductive materials in these systems assists bones proliferation and differentiation, hence the generation of new bone materials is enhanced. Some of these systems can also provide mechanical support for the long bones during the healing process. Most important, if the local systems are designed to be injectable to the affected site and biodegradable, they will reduce the level of invasion required for implantation and can win the patients’ compliance and reduce the healing period. They will also allow multiple injections during the course of therapy to guard against the side effect of the long-term systemic therapy. The current review presents different available approaches for delivering antimicrobial agents for the treatment of osteomyelitis focusing on the recent advances in researches for local delivery of antibiotics.

HIGHLIGHTS

Chronic osteomyelitis is a challenging disease due to its serious mortality and morbidity rates and limited effective treatment options.

Local drug delivery systems are receiving great attention in the recent decades.

Osteoinductive and osteoconductive materials in the local systems assists bones proliferation and differentiation

Local systems can be designed to provide mechanical support for the long bones during the healing process.

Designing the local system to be injectable to the affected site and biodegradable will reduces the level of invasion and win the patients’ compliance.

Defeating antibiotic-resistant bacteria with protein-resistant polyGGE film

Biofouling on medical device surfaces, which is initiated by protein adsorption and adhesion of microbes especially the antibiotic-resistant bacteria, attracts global attention for centuries due to its enduring challenges in healthcare. Here, the antifouling effect of hydrophilic poly(glycerol glycidyl ether) (polyGGE) film is explored in comparison to hemocompatible and protein-resistant control polymers. The chemical and thermomechanical stability of polyGGE in hydrated conditions at body temperature was achieved via adjusting UV curing and KOH quenching time. The polyGGE surface is inert to the plasma protein adsorption and interfered the metabolism conditions, biofilm formation and growth of both Gram negative (Gram-) and antibiotic-resistant Gram positive (Gram+) bacteria. These results indicate the potential application of polyGGE for combating the risk of hospital-acquired infections and preventing drug-resistant superbug spreading.

Calcium sulphate as a drug delivery system in a deep diabetic foot infection

Treating diabetic foot infection is costly, time consuming and challenging for the patient and clinician alike. It requires a multidisciplinary approach to provide a favourable outcome but all too often results in amputation. We present a patient with Type 2 diabetes who attended clinic with a limb threatening foot infection complicated by osteomyelitis and requiring emergency surgery and antibiotic administration. Our patient underwent surgery by means of an incision and drainage procedure with local antibiotic administration to augment systemic antibiotics. The wound was packed with calcium sulphate (Stimulan(®) Biocomposites Ltd.) impregnated with gentamicin and vancomycin to enable high antibiotic concentrations at the site of infection. The patient made a full recovery at four months requiring only minimal bone excision to maintain a functional foot. This case demonstrates an alternative route for antibiotic administration to overcome some of the limitations of systemic administration including penetration at the site of infection, systemic toxicity, prolonged hospital admission and cost. This route of administration is being increasingly used as an alternative to systemic antibiotics at our centre.

Silica-Gentamicin Nanohybrids: Synthesis and Antimicrobial Action

Orthopedic applications commonly require the administration of systemic antibiotics. Gentamicin is one of the most commonly used aminoglycosides in the treatment and prophylaxis of infections associated with orthopedic applications, but gentamicin has a short half-life. However, silica nanoparticles (SiO₂ NPs) can be used as elegant carriers for antibiotics to prolong their release. Our goal is the preparation and characterization of SiO₂-gentamicin nanohybrids for their potential antimicrobial administration in orthopedic applications. In vitro gentamicin release profile from the nanohybrids (gentamicin-conjugated SiO₂ NPs) prepared by the base-catalyzed precipitation exhibited fast release (21.4%) during the first 24 h and further extension with 43.9% release during the five-day experiment. Antimicrobial studies of the SiO₂-gentamicin nanohybrids versus native SiO₂ NPs and free gentamicin were performed against Bacillus subtilis (B. subtilis), Pseudomonas fluorescens (P. fluorescens) and Escherichia coli (E. coli). SiO₂-gentamicin nanohybrids were most effective against B. subtilis. SiO₂ NPs play no antimicrobial role. Parallel antimicrobial studies for the filter-sterilized gentamicin were performed to assess the effect of ultraviolet (UV)-irradiation on gentamicin. In summary, the initial fast gentamicin release fits the need for high concentration of antibiotics after orthopedic surgical interventions. Moreover, the extended release justifies the promising antimicrobial administration of the nanohybrids in bone applications.