Effect of the Peritoneal Fluid of the Guinea Pig on Strains of Enteric Bacilli

Abstract

ALTHOUGH the complement-dependent bactericidal system of normal mammalian serum has been actively studied since the early descriptions of Nuttall¹ and Buchner², its role in native immunity is a matter of disagreement³. Recent reports indicate that strains of Gram-negative enteric bacilli isolated from patients' blood or from burns are ordinarily resistant to this system^4,5. When equal numbers of a strain of E. coli resistant to this bactericidal effect and of one sensitive to it are injected into a rabbit, both strains ordinarily can be cultured from the blood stream 24 hr. following injection; but organisms from the resistant strain are 10–20 times more numerous⁶. There have been reports that strains of enteric bacilli resistant to the action of the complement-dependent system are more virulent for the mouse than are sensitive strains^7,8. Such observations lead to the belief that bacterial strains sensitive to the action of this system are less likely to cause or maintain an infection than are resistant strains.