Immunoglobulin G: Potentiation of Tobramycin and Azlocillin in the Treatment of Pseudomonas aeruginosa Sepsis in Neutropenic Mice and Neutralization of Exotoxin A in Vivo

Mice with cyclophosphamide-induced neutropenia were challenged with four immunotypes of Pseudomonas aeruginosa by contamination of a small dorsal surface wound. The infections were lethal; 100% of control animals (n = 80) treated only with albumin died. Administration of an immunoglobulin G intravenous preparation (IGIV) and/or therapy with tobramycin or azlocillin was begun 16 hr after challenge. Mortality among mice (n = 120) treated only with an antibiotic was 75.0%, while that among mice (n = 80) treated only with IGIV was 78.8%. Combination therapy with IGIV and an antibiotic (n = 120) resulted in mortality of 38.3%. The protection afforded by IGIV may have resulted in part from neutralization of exotoxin A, as mice treated with IGIV before challenge with exotoxin A were subject to lower mortality and had lower levels of serum aspartate and alanine aminotransferases than controls.