Non-specific resistance of mice to bacteria, induced by an acellular extract from Pseudomonas aeruginosa.

Antibacterial activity of an acellular extract from Pseudomonas aeruginosa (AEP) was assessed in mice infected with bacteria including extracellular and intracellular bacteria. It was shown that AEP strongly increased resistance of mice to bacterial infections. The protective effect was maximal between days 2 and 5 after inoculation of AEP, and subcutaneous inoculation was most efficient. The ED90 of AEP was about 30 micrograms per mouse (i.e. about 10 times less than that of Corynebacterium parvum). AEP caused an increased in Listeria monocytogenes destruction in the spleen and liver. AEP-treated mice exhibited an early recruitment of phagocytes after bacterial challenge in the peritoneal cavity. Furthermore, phagocytosis and O2-dependent bactericidal systems were studied by measuring the chemiluminescence response from macrophages under exposure to L. monocytogenes and Staphylococcus aureus: the response was earlier and higher from AEP-stimulated macrophages than from controls. It was concluded that AEP induces an early recruitment of phagocytes and increases their bactericidal activity.