Effects of adjunctive treatment with combined cytokines in a neutropenic mouse model of multidrug-resistant Enterococcus faecalis septicemia

Study Objective. To examine whether the antienterococcal efficacy of a regi men of gentamicin plus vancomycin combined with granulocyte colony-stimulat ing factor (G-CSF) is enhanced by concurrent therapy with interferon-gamma (IFN-gamma). Setting. Hospital laboratory. Intervention. Mice rendered neutropenic by cyclophosphamide were intraperit oneally inoculated with a gentamicin- and vancomycin-resistant Enterococcus faecalis isolate. Measurements and Main Results. Infected animals were randomized into treatm ent groups that received G-CSF alone or in combination with various dosages of IFN-gamma. Additional groups of animals received vancomycin; G-CSF, G-C SF plus vancomycin, IFN-gamma, and G-CSF; or vancomycin with both cytokines . Addition of IFN-gamma to G-CSF regimen resulted in no significant change (p>0.05) in survival, compared with treatment with G-CSF alone. Also, the a ntienterococcal efficacy of antibiotic plus G-CSF was not modified by coadm inistration of IFN-gamma. Conclusion. This study suggests that adjunctive application of combined cyt okines may not be more beneficial than only G-CSF in combination with an an tibiotic to treat multidrug-resistant enterococcal infection.