Potential of Continuous Local Antibiotic Perfusion Therapy for Fracture-Related Infections

Effective biofilm eradication in MRSA isolates with aminoglycoside-modifying enzyme genes using high-concentration and prolonged gentamicin treatment

Bone and soft tissue infections caused by biofilm-forming bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), remain a significant clinical challenge. While the control of local infection is necessary, systemic treatment is also required, and biofilm eradication is a critical target for successful management. Topical antibiotic treatments, such as antibiotic-loaded bone cement (ALBC), have been used for some time, and continuous local antibiotic perfusion therapy, a less invasive method, has been developed by our group. However, the optimal antibiotics and concentrations for biofilms of clinical isolates are still not well understood. We examined the efficacy of high concentrations of gentamicin against MRSA biofilms and the role of gentamicin resistance genes in biofilm eradication. We collected 101 MRSA samples from a hospital in Japan and analyzed their gene properties, including methicillin and gentamicin resistance, and their minimum biofilm eradication concentration (MBEC) values. Our results showed that high concentrations of gentamicin are effective against MRSA biofilms and that even concentrations lower than the MBEC value could eliminate biofilms after prolonged exposure. We also identified three aminoglycoside/gentamicin resistance genes [aac(6')-aph(2″), aph(3')-III, and ant(4')-IA] and found that the presence or absence of these genes may inform the selection of treatments. It was also found that possession of the aac(6')-aph(2″) gene correlated with the minimum inhibitory concentration/MBEC values of gentamicin. Although this study provides insight into the efficacy of gentamicin against MRSA biofilms and the role of gentamicin resistance genes, careful selection of the optimal treatment strategy is needed for clinical application.

IMPORTANCE

Our analysis of 101 MRSA clinical isolates has provided valuable insights that could enhance treatment selection for biofilm infections in orthopedics. We found that high concentrations of gentamicin were effective against MRSA biofilms, and even prolonged exposure to concentrations lower than the minimum biofilm eradication concentration (MBEC) value could eliminate biofilms. The presence of the aac(6')-aph(2″) gene, an aminoglycoside resistance gene, was found to correlate with the minimum inhibitory concentration (MIC) and MBEC values of gentamicin, providing a potential predictive tool for treatment susceptibility. These results suggest that extended high concentrations of local gentamicin treatment could effectively eliminate MRSA biofilms in orthopedic infections. Furthermore, testing for gentamicin MIC or the possession of the aac(6')-aph(2″) gene could help select treatment, including topical gentamicin administration and surgical debridement.

Management of Infected Tibial Nonunion: Combining Synthetic Bone Grafting with Continuous Local Antibiotic Perfusion (CLAP)

BACKGROUND Infection control and reconstruction of bone and soft tissue are essential for treating infected nonunion. Continuous local antibiotic perfusion (CLAP) is a drug delivery system that continuously delivers antibiotics at the required concentration, area, and duration. This case report describes the instance of infected nonunion in which infection eradication and bone union were achieved using CLAP and synthetic bone grafting while retaining the implant. CASE REPORT The case was a 31-year-old woman with an infected nonunion. After she underwent osteosynthesis using nail for open fractures of tibia and fibula, bone union remained unachieved, and she exhibited skin defects and draining of pus. Following the removal of the infected granulation tissue from the bone defects, 2 bone marrow needles, serving as intramedullary antibiotic perfusion (iMAP) pins, were inserted into the medullary cavity tibia. A double-lumen tube was placed in the subcutaneous pocket as the intra-soft tissue antibiotic perfusion (iSAP) tube. No bone mobility was observed around the bone defect and nail, and replacement of the implant was not necessary. Beta-tricalcium phosphate was transplanted to the bone defect, and negative pressure wound therapy was applied. Gentamicin was injected continuously through iMAP and iSAP. Finally, the infection was eradicated, and cortical bone bridging was observed without additional surgery or adverse effects. CONCLUSIONS CLAP emerges as a viable treatment option for infected nonunion, as it enables the delivery of antibiotics at a concentration sufficient for infection control while providing the surgeon with flexibility to design the area, dosage, and duration of antibiotic delivery.

Effective Management of Methicillin-Resistant Shoulder Septic Arthritis Using Continuous Local Antibiotic Perfusion: A Case Study and Long-Term Follow-Up

BACKGROUND Septic arthritis of the shoulder is a rare and challenging condition to treat. Typically, arthroscopic debridement is the common approach. Specifically, septic arthritis of the shoulder caused by methicillin-resistant bacteria is extremely difficult to cure due to persistent infection and limited antibiotic options. However, recent studies have demonstrated that continuous local antibiotic perfusion (CLAP) can provide favorable results for bone and soft tissue infections. By administering the antibiotics required to suppress the biofilm, CLAP can effectively treat the infection while sparing the tissue. CASE REPORT A 46-year-old woman undergoing long-term hemodialysis treatment for congenital anomalies of the kidney and urinary tract experienced severe pain in the left shoulder joint during glucocorticoid treatment for amyloid arthritis of the right shoulder. Despite the absence of fever, significant swelling and fluid accumulation were observed in the left shoulder joint, leading to the performance of a puncture. A bacterial examination of the puncture fluid detected methicillin-resistant coagulase-negative Staphylococcus epidermidis (MRCNS). In this report, we present a case in which CLAP was administered for septic arthritis of the shoulder caused by methicillin-resistant bacteria. After irrigation debridement, the patient received intravenous antibiotics and CLAP. Following the initiation of treatment, the dosage of antibiotics was adjusted while performing therapeutic drug monitoring. An early improvement in the inflammatory response and sedation of the infection was observed, with no relapse after 2 years. CONCLUSIONS Septic arthritis can lead to serious functional impairment if left untreated. CLAP is a promising option for managing septic arthritis of the shoulder.

DAIR in treating chronic PJI after total knee arthroplasty using continuous local antibiotic perfusion therapy: a case series study

BACKGROUND

Antimicrobial agents are administered via intramedullary antibiotic perfusion (iMAP)/intrasoft tissue antibiotic perfusion (iSAP) to infected lesions to control osteoarticular and soft tissue infections. Continuous local antibiotic perfusion (CLAP) has been reported to be useful. This study aimed to investigate the outcomes of DAIR combined with CLAP for chronic PJI after total knee arthroplasty performed at our hospital.

SUBJECTS AND METHODS

Six patients (male; one case, female; five cases, mean age 79.5 years (70-94)) underwent CLAP for chronic PJI after TKA at our hospital between July 2020 and June 2022. They were followable for at least one year after surgery. Seven months (17-219), with a mean follow-up of 24.3 months (12-36). In addition to direct debridement and insert exchange, systemic antimicrobial treatment, and CLAP with gentamicin were performed using NPWT. We investigated the organisms causing the inflammation, the duration of iMAP/iSAP implantation, the maximum daily dose of GM, the maximum GM blood concentration, and the presence or absence of GM-induced adverse events.

RESULT

Two of six patients had a recurrence of infection at five weeks and five months after initial CLAP and required repeat CLAP treatment, but all patients could preserve their components. The organisms responsible for the flare-ups were MSSA in three cases: ESBL-producing E. coli, mixed MSSA and streptococcal infection, Klebsiella pneumonia in one case each, and unknown pathogens in one case. CLAP therapy for all patients was administered eight times in 6 cases: iMAP, mean: 10.0 days (5-16); iSAP, mean: 19.3 days (15-28); GM dose, mean: 162.5 mg/day (80-240); and GM blood concentration, mean: 1.4 µg/mL (0.2-5.0). Adverse events included one case of reversible acute kidney injury during CLAP in a patient with recurrent infection. DAIR with CLAP for chronic post-TKA infection can be a useful treatment option to preserve components and allow the infection to subside, provided the implant is not markedly loosened.

Cell migration, DNA fragmentation and antibacterial properties of novel silver doped calcium polyphosphate nanoparticles

To combat infections, silver was used extensively in biomedical field but there was a need for a capping agent to eliminate its cytotoxic effects. In this study, polymeric calcium polyphosphate was doped by silver with three concentrations 1, 3 or 5 mol.% and were characterized by TEM, XRD, FTIR, TGA. Moreover, cytotoxicity, antibacterial, cell migration and DNA fragmentation assays were done to assure its safety. The results showed that the increase in silver percentage caused an increase in particle size. XRD showed the silver peaks, which indicated that it is present in its metallic form. The TGA showed that thermal stability was increased by increasing silver content. The antibacterial tests showed that the prepared nanoparticles have an antibacterial activity against tested pathogens. In addition, the cytotoxicity results showed that the samples exhibited non-cytotoxic behavior even with the highest doping concentration (5% Ag-CaPp). The cell migration assay showed that the increase in the silver concentration enhances cell migration up to 3% Ag-CaPp. The DNA fragmentation test revealed that all the prepared nanoparticles caused no fragmentation. From the results we can deduce that 3% Ag-CaPp was the optimum silver doped calcium polyphosphate concentration that could be used safely for medical applications.

Periprosthetic Joint Infection Following Reverse Shoulder Arthroplasty Treated With Continuous Local Antibiotic Perfusion: A Case Report

Prosthetic joint infection (PJI) is a crucial complication of reverse shoulder arthroplasty (RSA). Continuous local antibiotic perfusion (CLAP) with a high-concentration antimicrobial pharmacy administration method has recently received attention owing to its effectiveness in the treatment of bone and soft tissue infections. We herein report a case of PJI following RSA that was successfully treated with CLAP without removal of the entire implant. A 73-year-old woman with comorbidities of diabetes mellitus and hypertension underwent RSA. The wound was found to be swollen eight weeks after RSA, and purulent content that was positive for Propionibacterium granulosum was identified. Blood samples indicated a mildly elevated inflammatory response. With a diagnosis of PJI spread from the intra-articular to subcutaneous regions without implant loosening, the patient underwent surgical treatment nine weeks after RSA. The contaminated tissues were thoroughly debrided, and the prosthetic joint was preserved by replacing the glenosphere and polyethylene liner. Intra-soft tissue antibiotic perfusion (iSAP) tubes and effluent drains were placed intra-articularly and subcutaneously, and gentamicin was infused continuously for 12 days. In addition, ceftriaxone and rifampicin were administered. The patient was subsequently treated with minocycline and sulfamethoxazole/trimethoprim or clindamycin for eight weeks. The inflammatory reaction became negative six weeks postoperatively, and the patient had no recurrence at 15 months postoperatively. Treatment of PJI is considered a long-lasting, challenging process. This case report supports the feasibility of using CLAP in the treatment of PJI.