Aim

Aim of this study is to present the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating*, in patients undergoing internal osteosynthesis for closed fractures.

Aim

Infection remains among the first reasons of failure of joint prosthesis. According to various preclinical reports, antibacterial coatings of implants may prevent bacterial adhesion and biofilm formation. Aim of this study is to present the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating*, in patients undergoing hip or knee prosthesis.

Toll-like receptors (TLRs) are crucial components of the immune system that recognize microbial infection and trigger anti-microbial host defense responses. Gram positive bacteria are causative factors of bone infections, as they alter the balance of coordinated activities during bone remodeling, stimulating osteoclastogenesis. The aim of the study was to investigate whether genetic variation in TLR2 and TLR4 genes predisposes to bone infections’ susceptibility.

One hundred and twenty patients with bone infections (osteomyelitis) and 200 healthy controls were genotyped for two single nucleotide polymorphisms (SNPs), R753Q [A/G] in TLR2 gene and T399I [C/T] in TLR4 gene. DNA was extracted from whole blood and the above SNPs were typed with PCR-RFLP (Polymerase Chain Reaction- Restriction Fragment Length Polymorphism) method for genotype identification. All patients were infected by Gram-positive bacteria, predominantly Staphylococcus aureus. Statistical analysis was carried out using the chi-square test.

We observed a significantly increased frequency in patients carrying the GA genotype of TLR2 R753Q polymorphism compared to controls (p<0.05). We also found that the A allele was more common in patients than in controls. All individuals carrying the A allele were heterozygous for this variant, while homozygous mutant individuals were not detected in the patients and the control group. In contrast, we found that the TLR4 T399I [C/T] SNP was similarly distributed among the two groups (patients and controls). The mechanism through which TLR2 mediates its effect in bone infections is under investigation.

A significant difference was observed in the genotype frequency of TLR2 R753Q [A/G] polymorphism in patients, suggesting that genetic variability in TLR2 gene may be associated with susceptibility to osteomyelitis in response to bacterial invasion in the bone.

Report of a case of migrating periprosthetic infection from a hip replacement to a contralateral knee joint undergoing a total knee replacement.

We present a 74-year old female patient who underwent a total hip arthroplasty of the left hip after a subcapital fracture of the femur. Four months after the index procedure the patient presented with signs and symptoms of infection of the operated joint. Staph aureus and Enterococcus faecalis were recognized as the infecting bacteria. The implants were removed, cement spacers were placed and a total hip arthroplasty was performed again after three months. Unfortunately, infection ensued again and the patient underwent three more procedures until the joint was considered clean and t he hip remained flail without implants. The patient elected to undergo a total knee arthroplasty due to severe osteoarthritis of right knee. Intraoperatively tissue samples were taken and sent for cultures which identified Enterococcus faecalis present in the knee joint. Enterococcus migrated from the infected hip to nonoperated knee joint. Intravenous antibiotics were administered for three weeks but the knee presented with infection of the arthroplasty ten months after its insertion. The implants were removed the joint was debrided and cement spacers were inserted.

The patient decided not to proceed with another procedure and she remains with the cement spacers in her knee.

Rare report of migrating periprosthetic infection. Nosocomial enterococci acquired resistance cannot be ruled out. Unique characteristics in enterococci antibiotic resistance and biofilm formation.

Infection is among the first reasons for failure of orthopedic implants. Various antibacterial coatings for implanted biomaterials are under study, but only few technologies are currently available in the clinical setting. Previous studies showed the in vitro and in vivo efficacy and safety of a fast resorbable (<96 h) hyaluronic and polylactic acid based hydrogel, loaded with antibiotic or antibiofilm agents (DAC®, Novagenit Srl, Mezzolombardo, TN). Aim of this study is to report the results of the largest clinical trial in trauma and orthopedic patients.

In this prospective, controlled, study, a total of 184 patients (86 treated with internal osteosinthesis for closed fractures and 98 undergoing cementless total hip or knee joint prosthesis) were randomly assigned in three European orthopaedic centers to receive antibiotic-loaded DAC coating or to a control group, without coating. Pre- and post-operative assessment of laboratory tests, wound healing (ASEPSIS score), clinical score (SF-12 score) and x-rays were performed at fixed time intervals. Statistical analysis was performed with Fisher exact test or Student's t test. Significance level was set at p<0.05.

The study was approved by the local Ethical Committee and all patients provided a written informed consent.

On average, wound healing, clinical scores, laboratory tests and radiographic findings did not show any significant difference between the two-groups at a mean 12 months follow-up (min: 6, max: 18 months).

Four surgical site infections and two delayed union were observed in the control group compared to none in the treated group.

No local or systemic side effects, that could be related to DAC hydrogel coating, were noted and no detectable interference with bone healing or osteointegration could be found

This is the largest study, with the longest follow-up, reporting on clinical results after the use of a fast-resosrbable anti-bacterial hydrogel coating for orthopaedic and trauma implants. Our results show the safety of the tested coating in different indications; although not statistically significant, the data also show a trend towards surgical site infection reduction, as previously demonstrated in the animal models.

Of the 6075 patients enrolled in EU-CORE registry, 206 patients had orthopaedic device-related infections. Significant underlying diseases were reported in 71% patients, most frequently cardiovascular disease (38%). The common sites of infection were knee (40%) and hip (33%). Among the 170 patients with available culture results, 135 (79%) were positive. Coagulase-negative staphylococci (CoNS, 44%) and Staphylococcus aureus (43%, of those 47% were methicillin resistant) were the most commonly isolated pathogens. Daptomycin was used empirically in 48% patients and as second-line therapy in 67% patients. During daptomycin therapy, 67% patients had undergone surgery (debridement, 61%; removal of foreign device, 39%; incision and drainage, 9%). Over half of the inpatients (54%) received concomitant antibiotics. Daptomycin was most frequently prescribed at a dose of 6 mg/kg/day (48%), with a median duration of therapy of 16 (range, 1–176) days. The overall clinical success rate was 85%, and was similar whether daptomycin was administered as first- or second-line therapy. The success rates achieved for infections caused by S. aureus and CoNS were 86% and 83%, respectively. Among the 79 patients who entered the long-term follow-up, 85% had a sustained response. Adverse events (AEs) and serious AEs possibly related to daptomycin were reported in 4.4% and 1.9% patients, respectively.

Results from this real-world clinical experience showed that daptomycin is an effective and well-tolerated treatment option for orthopaedic device-related infections with a high success rate up to 2 years of follow-up.