Local delivery of linezolid in the treatment of complex orthopedic bone and joint infections in patients with vancomycin allergy: a case series

Introduction: Osteomyelitis is a challenging bone infection associated with ischemia, trauma, or various surgical procedures (e.g., joint reconstruction). Treatment involves eradicating infected bone and soft tissue, local antibiotic delivery, and a 6-week course of antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) infections are common, and vancomycin is the standard treatment, but alternatives like linezolid are needed in vancomycin-resistant and vancomycin-allergic patients. Methods: A retrospective chart review was conducted on patients treated by the senior author between 2013 and 2021. The study included patients who received local delivery of linezolid for bone and/or joint infection with documented evidence of vancomycin allergy. Patient demographics, surgical details, linezolid delivery method, and outcomes were recorded. Clinical outcomes and subsequent procedures leading to infection eradication were documented. Results: A total of 13 patients were treated with linezolid-antibiotic-laden spacers with polymethyl methacrylate (PMMA) carrier. Nine patients were successfully treated using limb-salvage techniques and were still infection-free after a mean follow-up of 55.5 months. Conclusions: Linezolid-loaded bone cement is an option for managing chronic bone and joint infections, particularly MRSA, in patients with vancomycin allergy.

Biomechanical comparison of tigecycline loaded bone cement with vancomycin and daptomycin loaded bone cements

OBJECTIVE

The objectives of this study were "1" to analyze the compressive and tensile mechanical strength characteristics of tigecycline loaded bone cement and "2" to compare them with those of vancomycin and daptomycin loaded bone cements which are used in prosthetic joint infections complicated with resistant microorganisms.

METHODS

In this study, three experimental groups, which consisted of vancomycin (subgroups containing 1 g, 2 g, and 3 g vancomycin), daptomycin (subgroups containing 0.5 g, 1 g, and 1.5 g daptomycin), and tigecycline (subgroups containing 50 mg, 100 mg, and 150 mg tigecycline) and one control group without antibiotics were used. Using a standardized protocol, all antibiotic loaded bone cements were prepared. For each antibiotic group, including the control group, 10 samples were tested. All samples were biomechanically tested in terms of compressive strength and tensile strength.

RESULTS

Compression tests showed that all determined antibiotic concentrations resulted in a significant decrease when compared with the control group (p<0.0011). Vancomycin and daptomycin study groups demonstrated lower tensile strength than the control group (p<0.0011). However, comparison of tensile values of tigecycline study groups with the control group revealed no significant difference (p>0.0011). In addition, all statistically significant results from between groups comparisons revealed higher tensile and compressive mechanical strength values for the tigecycline groups (p<0.0011).

CONCLUSION

Evidence from this study has demonstrated that tigecycline loaded bone cement may have no mechanical disadvantage compared with vancomycin and daptomycin loaded bone cements in terms of mechanical strength when used at defined concentrations.

Tibial Osteomyelitis Caused by Carbapenem-Resistant Enterobacter cloacae

A 31-year-old man presented with a symptomatic tibial non-union following an open tibia fracture sustained in India. The open fracture was persistently draining for 8 months following the initial injury. The decision was made to revise his tibia fracture to promote union. Intraoperative cultures of the non-union site during the revision procedure revealed osteomyelitis caused by carbapenemase-producing Enterobacter cloacae which was multi-drug resistant to all antibiotics except for tigecycline. The patient was treated successfully with a tigecycline-impregnated antibiotic spacer and intravenous tigecycline with repeat bone cultures demonstrating eradication of the infection. Eight weeks into treatment (1 year from initial injury), the patient developed new pain and swelling in the adjacent proximal fibula of the limb treated for osteomyelitis. MRI and biopsy revealed Ewing sarcoma. The patient underwent transfemoral amputation. This report describes a management protocol of carbapenemase-resistant post-traumatic osteomyelitis with no evidence of infection recurrence.

Efficacy of antiretroviral compounds against Toxoplasma gondii in vitro

The obligate intracellular parasite Toxoplasma gondii can infect nearly all warm-blooded animals, including humans. Although infection with this parasite is generally benign, severe illness may occur in infected individuals if their immunity becomes less competent, such as in human immunodeficiency virus (HIV)-infected patients. In this study, the inhibitory activity of 44 commonly used antiretroviral compounds was determined against T. gondii in vitro. Of the 44 tested antiretroviral compounds, 14 showed potency against T. gondii at IC₅₀ concentrations (concentration inhibiting T. gondii tachyzoite growth by 50%) ranging from 1.18 ± 2.21 µM (nelfinavir) to 18.89 ± 1.87 µM (trovirdine). Of the 14 potent antiretroviral compounds, 7 are HIV-1 protease inhibitors. This study also investigated whether co-administration of these 14 antiretroviral compounds interferes with the anti-T. gondii activity of existing anti-T. gondii drugs, namely sulfadiazine and pyrimethamine. The results showed no significant interaction between any of the 14 tested antiretroviral compounds and pyrimethamine or sulfadiazine. These results warrant investigation of whether administration of the lead antiretroviral drugs with highly potent anti-T. gondii activity to HIV patients may help to limit the occurrence of toxoplasmic encephalitis.

Tocopherol polyethylene glycol succinate-modified hollow silver nanoparticles for combating bacteria-resistance

TPGS capped AgNPs could cross the bacterial cell wall and inhibit the activity of efflux pumps, eventually antagonize drug-resistance in the acute peritonitis model mice effectively.