Comparisons of Five Toxicity Parameters of Serratia marcescens Endotoxins

Abstract

Phenol-water purification of TCA extracted Serratia marcescens endotoxin results in an apparent enhancement of toxicity as measured by two methods for testing biological activity, whereas three other methods indicate only an insignificant increase in toxicity. Partial degradation of endotoxin by NaOH shows a rapid loss of chick embryo lethality both by the iv and CAM routes of inoculation. Mouse lethality persists longer, almost complete detoxification occurring between 1 and 6 hours of NaOH treatment. The FI40 figures in rabbits tend to show an increase in pyrogenicity after 5 min of treatment and a progressive decrease between 30 min and 24 hours, although a low level of pyrogenicity is retained at the latter time. Shwartzman reactivity increases up to 1 hour of NaOH treatment, followed by a decrease to approximately the initial level after 24 hours of treatment and thus would appear to be a less reliable indicator of detoxification when compared to the other testing procedures. It is thus seen that one method of testing endotoxin may indicate an active preparation whereas another parameter may indicate otherwise to a greater or lesser extent. As a result, it is important to recognize the inherent danger involved in using a single assay technique for describing the toxic potency of an endotoxin preparation. The observed discrepancies in biological assays also indicate that the mode of endotoxic action is obviously triggered and channeled by a number of different pathways in the various host systems.