Randomized Controlled Study on the Safety and Efficacy of Phage Cocktail in the Treatment of Multidrug-Resistant Bacterial Skin Infections

This study addresses the increasingly severe global public health challenge of antibiotic resistance, focusing on exploring phage therapy as a potential treatment strategy for multidrug-resistant bacterial skin infections. Bacteriophages, with advantages such as high specificity, low propensity for inducing resistance, and minimal side effects, have shown promise in preliminary clinical research for scenarios like chronic wound infections, demonstrating potential in reducing bacterial load and promoting healing. To this end, the study is designed as a prospective, double-blind, non-inferiority randomized controlled clinical trial, aiming to systematically evaluate the efficacy and safety of phage therapy compared to a placebo or standard treatment in patients with multidrug-resistant bacterial skin infections.

The study plans to enroll patients aged 18 to 75 years, clinically diagnosed with a skin infection and with a wound area between 4 and 225 square centimeters. The infection must not involve deep tissue and should be suitable for topical treatment. All enrolled cases must have pathogenic bacteria detected in secretions or wound samples, and these bacteria must be resistant to key antibiotics (such as carbapenems) or show poor response to antibiotic therapy despite *in vitro* sensitivity. Patients who have received systemic antibacterial treatment within 72 hours before enrollment with no significant improvement may also be included. Participants of childbearing potential must agree to use effective contraception during the study and voluntarily provide written informed consent.

Exclusion criteria primarily include: infections that can be effectively controlled by existing antimicrobials, or pathogens that are insensitive to the phage cocktail used in the study; pregnant or lactating women; patients whose infection symptoms have improved after using antimicrobials within 72 hours before enrollment; those receiving long-term or high-dose corticosteroids, immunosuppressants, chemotherapy, or other treatments that may interfere with the results; participation in other antimicrobial-related clinical trials within the past month; presence of severe wound infections (e.g., necrotizing fasciitis), chronic inflammatory skin diseases, multiple limb ulcers, non-removable implants, or gangrene; anticipated need for amputation surgery; history of clear allergic diseases, immune deficiency (including HIV positivity), mental disorders, or epilepsy; and any other condition deemed by the investigator as unsuitable for participation. These strict inclusion and exclusion criteria aim to select an appropriate target population, ensuring the scientific rigor and credibility of the study results.