Infectious
peritonitis results from bacterial contamination of the abdominal cavity. Conventional
antibiotic treatment is complicated both by the emergence of
antibiotic-resistant bacteria and by increased patient populations intrinsically at risk for
nosocomial infections. To
complement antibiotic therapies, the efficacy of direct, locally applied pooled human
immunoglobulin G (
IgG) was assessed in a murine model (strains CF-1, CD-1, and CFW) of
peritonitis caused by intraperitoneal inoculations of 10(6) or 10(7) CFU of Pseudomonas aeruginosa (strains IFO-3455, M-2, and MSRI-7072). Various doses of
IgG (0.005 to 10 mg/mouse) administered intraperitoneally simultaneously with local bacterial challenge significantly increased survival in a dose-dependent manner. Local intraperitoneal application of 10 mg of
IgG increased animal survival independent of either the P. aeruginosa or the murine strains used. A local dose of 10 mg of
IgG administered up to 6 h prophylactically or at the time of bacterial challenge resulted in 100% survival. Therapeutic 10-mg
IgG treatment given up to 12 h postinfection also significantly increased survival. Human
IgG administered to the mouse peritoneal cavity was rapidly detected systemically in serum. Additionally, administered
IgG in peritoneal lavage fluid samples actively opsonized and decreased the bacterial burden via phagocytosis at 2 and 4 h post-bacterial challenge. Tissue microbial quantification studies showed that 1.0 mg of locally applied
IgG significantly reduced the bacterial burden in the liver, peritoneal cavity, and blood and correlated with reduced levels of
interleukin-6 in serum.