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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.

Endotoxin may be characterized by its primary toxic and secondary toxic actions. If we assume that the first effect of endotoxin is the release of different mediators from different sites, then this action, together with the effects of mediators on different tissues, would be a direct effect. The primary toxic action is exerted on adrenergic nervous structures and on certain cellular targets, but these structures are affected without involvement of immune factors. The secondary toxic effect is exerted on cellular targets by means of immunologic mechanisms; both immediate and delayed hypersensitivity are elicited by means of opsonin and complement. Endotoxin is less toxic to cells in the absence of immune factors.

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.

ALTHOUGH there have been previous claims that lesions like the Shwartzman phenomenon can be produced by two large injections of endotoxin into the same site in the skin, in animals other than rabbits (for example, mice)1, it has been stated that the classical Shwartzman phenomenon is immunologically non-specific in that it does not depend on antigen–antibody reaction2,3, and it can be elicited only in rabbits2–4. Recently, however, I have succeeded in demonstrating that the first phase of the Shwartzman phenomenon, that is, preparation of the skin by endotoxin, is a specific reaction depending on a well-characterizable immunological mechanism, namely, the phenomenon of local endotoxin hypersensitivity, and that in appropriate circumstances (a–e) it may be elicited by endotoxins on the skin of guinea pigs and rats also.

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