spp. are causative agents of healthcare-associated infections in patients who are immunocompromised and use medical devices. The antibiotic resistance crisis has led to an increase in infections caused by these bacteria, which can develop into potentially life-threatening illnesses if not treated swiftly and effectively. Thus, new treatment options for are urgently required. Phage therapy can offer an alternative to ineffective antibiotic treatments for antibiotic-resistant bacteria infections. The aim of the present study was to produce a safe and effective phage cocktail treatment against and , both in liquid culture and an infection model. The phage cocktail was significantly more effective at killing and strains compared with monophage treatments. Preliminary phage cocktail safety was demonstrated through application in the model: where the phage cocktail induced no toxic side effects in . In addition, the phage cocktail significantly improved the survival of when administered as a prophylactic treatment, compared with controls. In conclusion, our phage cocktail was demonstrated to be safe and effective against spp. in the infection model. This provides a strong case for future treatment for infections, either as an alternative or adjunct to antibiotics.IMPORTANCE infections are a concern in individuals who are immunocompromised and are becoming increasingly difficult to treat with antibiotics due to their drug-resistant properties. Bacteriophage is one potential alternative therapy that could be used to tackle these infections. The present study describes the design of a non-toxic phage cocktail that improved the survival of infected with . This phage cocktail demonstrates potential for the safe and effective treatment of infections, as an adjunct or alternative to antibiotics.