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The frequent and inappropriate use of antibiotics in hospitals increases the number of resistant hospital bacterial strains. Apart from Staphylococci and Streptococci, different Gram negatives--such as Klebsiella, Serratia, Pseudomonas, Proteus and E. coli strains--have been found in the hospitals and in the patients. Due to the resistance, it is difficult to find antibiotics against them. This fact puts forward the possibility of immunization especially by vaccination. Phenol-treated vaccine was prepared from the usual hospital strains and patients with colorectal cancer were immunized intramuscularly 7-10 days prior to the operation. The efficiency of the vaccine treatment was judged by the incidence of wound infections. The best results were obtained in patients whose previously estimated immunoreactivity was strong or normal. Immunospecificity could not be detected in the above treatment.

The Shwartzman-inducing activity in rabbits of purified endotoxin from four O serotypes of Escherichia coli, one strain of Salmonella typhi and one of Serratia marcescens was completely abolished by mixture, before intradermal injection, with homologous rabbit antiserum. The neutralization was highly specific since the same sera had no effect, under the conditions used, on endotoxin of heterologous serotypes or heterologous species. Neutralization of inducing activity did not require incubation or complement and was demonstrable independently of the species of endotoxin used for provocation. Inducing activity could be restored by extraction of the endotoxin—antiserum mixture with aqueous phenol, but not with trichloracetic acid.

Moderate resistance to Escherichia coli and Serratia marcescens endotoxin was induced in rabbits.