The importance of extracellular antigens in Pseudomonas cepacia infections

Abstract

Summary.A clinical isolate of Pseudomonas cepacia from a cystic fibrosis patient was examined for its ability to produce extracellular toxic material. The organism was grown to stationary phase in a defined medium and toxic material was isolated by ultrafiltration, ion-exchange chromatography on DEAE-Sephacel and gel-filtration chromatography on Sepharose 4B. It consisted of a surface carbohydrate antigen, lipopolysaccharide and protein, and had an LD50 (when injected intraperitoneally into mice) of 395k2Opg. The toxicity appeared to be associated with the lipopolysaccharide portion of the complex, because boiling for 15 min and exposure to proteolytic enzymes had no effect on toxicity. However, saponification destroyed the toxicity of the compound. Studies employing radial immunodiffusion with the sera of mice infected with this organism demonstrated production of the complex in uiuo at levels approaching those sufficient to produce death. When sublethal amounts of this complex were placed in the lungs of specific-pathogen-free rats, the lung pathology observed after 12, 24, 36 and 48 h was extensive. However, antibody generated in rabbits against this material could protect mice against the complex, as well as against challenge by the homologous organism. These data indicate that extracellular toxic material produced by P . cepacia may be responsible for the lethality and lung tissue destruction normally associated with an active pneumonia caused by this organism.

Production of an Extracellular Toxic Complex by Various Strains of Pseudomonas Cepacia

“…The serotyping and origin of these strains were described by McKevitt et al, 1987). The storage of the organisms and the media employed have been previously described (Anwar et al, 1983b) ; LD50 was determined as previously described (Straus et al, 1988) and calculated by the method of Reed and Muench (1938).…”

“…We have recently described the production of an extracellular toxic complex (ETC) that appeared to be responsible for the lethality and the extensive lung pathology produced by P. cepacia in animals (Straus et al, 1988). The ETC consisted of a surface Received 10 Oct. 1988; revised version accepted 25 Jan.…”

“…Saponification studies demonstrated that the toxicity of the ETC was most probably associated with the LPS. We also showed that this material enhanced the virulence of P. cepacia when co-injected into mice (Straus et al, 1988). Because the ETC from only one strain of P. cepacia was employed in the above study, we have examined additional strains for the production of this compound.…”

Lipopolysaccharide ofBurkholderia cepaciaand Its Unique Character To Stimulate Murine Macrophages with Relative Lack of Interleukin-1β-Inducing Ability

“…Lipase, protease, extracellular toxic complex, and lipopolysaccharide (LPS) released from the bacteria have been suggested as candidates for the virulence factors which cause pathological changes, such as accumulation of polymorphonuclear leukocytes and proteinaceous exudate in bronchial and alveolar lumina, injury and necrosis of bronchial epithelium, and disorganization of alveolar structure. The specific crucial trigger of the pneumonia and sepsis in B. cepacia infection, however, remains to be clarified (16,20,31,34,39).Among these four candidates, we were interested in LPS, a major component of the outer membrane in gram-negative bacteria, since it is assumed to play a central role in the induction of various pathophysiological responses, such as fever, disseminated intravascular coagulation, and shock in hosts suffering from gram-negative bacterial infections (22,27). LPSs of members of the Enterobacteriaceae, such as Escherichia coli and Salmonella, have been investigated intensively as typical LPSs with high endotoxic activity.…”

“…Lipase, protease, extracellular toxic complex, and lipopolysaccharide (LPS) released from the bacteria have been suggested as candidates for the virulence factors which cause pathological changes, such as accumulation of polymorphonuclear leukocytes and proteinaceous exudate in bronchial and alveolar lumina, injury and necrosis of bronchial epithelium, and disorganization of alveolar structure. The specific crucial trigger of the pneumonia and sepsis in B. cepacia infection, however, remains to be clarified (16,20,31,34,39).…”