Electron microscopy of leukocyte interaction with spores of Clostridium botulinum type A

Phagocytosis of toxic spores of Clostridium botulinum type A by human polymorphonuclear leukocytes as revealed by electron microscopy involves engulfment on contact and rapid inclusion into phagocytic vacuoles, followed by a rather slow process of spore germination within the next 8 h. Once germinated, spores appear to be degraded intra-phagocytically almost instantaneously. No outgrowth of spores into vegetative cells was observed either within the leukocytes or outside. Pathogenicity of C. botulinum spores seems to depend on germination of spores within the phagocyte, degradation of germinated spores, and release of spore-bound toxin into body fluids; thus causing potentially fatal botulism poisoning.