To evaluate the infection control effect of bacteriophage therapy in treatment of refractory orthopedic implant-associated infections

After undergoing standard surgical debridement for orthopedic implant-associated infection. Bacteriophage preparation was administered primarily via postoperative indwelling catheter infusion. An appropriate volume of bacteriophage solution (adjusted according to joint cavity size and clinical assessment) was instilled directly through the catheter into the infected site, twice daily (bid) for 3 consecutive days per treatment cycle. During administration, strict aseptic procedures were maintained, and the distribution of the bacteriophage preparation within the joint cavity was ensured. Throughout the treatment period, patients were closely monitored for local and systemic adverse events related to bacteriophage therapy.

The primary outcome of this study is the eradication of the target pathogen following bacteriophage treatment. Microbiological samples from the infection site will be collected before treatment and on days 1, 3, 5, and 7 after initiation of bacteriophage therapy for bacterial culture and identification.

Bacterial eradication is defined as two consecutive negative cultures for the target pathogen after completion of bacteriophage therapy.

If the target bacteria are still detected on day 3 or day 5, a reassessment will be performed to determine whether an additional cycle of bacteriophage therapy is required

The secondary outcome is the improvement of clinical symptoms and inflammatory indicators after bacteriophage therapy. Clinical improvement is defined by meeting the following criteria:

1. Body temperature returns to normal, and local signs of infection (swelling, erythema, pain) are significantly alleviated or resolved, with satisfactory wound healing (no purulent discharge or exudation);
2. Blood routine parameters (white blood cell count, neutrophil ratio) and inflammatory markers, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), show a progressive decline and return to normal ranges;
3. Drainage from the infection site is significantly reduced or absent;
4. Imaging examinations (e.g., X-ray, CT, or MRI) demonstrate significant resolution of inflammatory lesions.