Differences in antiopsonic effects of the extracellular products ofS. aureus andN. gonorrhoeae

Abstract

Extracellular products of S. aureus and N. gonorrhoeae decrease the etficacy of opsonization of these bacteria by blood serum. Antiopsonic activity of S. aureus exometabolites is exhibited predominantly during their contact with serum components bound to bacterial surface, which disturbed the reactions between opsonines and neutrophiis, as evidenced by decreased chemiluminescent signal during phagocytosis. With gonococci, this effect was observed predominantly during preliminary contact of their extracellular products with the serum, which attenuated the intensity of opsonization. Partial parallelism between changes in the neutrophil-stimulating activity of bacterial cultures and modification of their hydrophobic properties under the effect of the studied factors cannot be regarded as an absolute relationship. Key Words: Staphylococcus aureus; Neisseria gonorrhoeae; complement; opsonization; hydrophobic properties; chemiluminescenceThe reactions between microorganisms and neutrophilic phagocytes are a key component in the pathogenesis of staphylococcal and neisserial infections. Along with the resistance to the intracellular killing, the avoidance of the phagocytic reaction of a host organism is an important factor [8,13]. We have demonstrated this reaction in Staphylococcus aureus [3]: the efficacy of opsonization of bacterial cells by serum components was reduced by the extracellular protein A that shielded the Fc fragments of bound immunoglobulins and by an anticomplementary factor. The ability of Neisseria gonorrhoeae to inactivate the complement (mainly its C1 and C3 components) by the extracellular products [1] prompted us to investigate the probable antiopsonic effect and analyze the simiInstitute of Cellular and Extracellular Symbiosis, Ural Branch of the Russian Academy of Sciences, Orenbur~ larities and differences in the mechanisms of antiopsonic effects of staphylococcal and gonococcal products.We also studied modifications in the hydrophopic properties of staphylococci and gonococci caused by fixation of serum components. The need in this comparison is explained by important role of physical properties of bacterial surface for adhesion to eukaryotic cells, including the opsonization [14] and other processes associated with specific adhesion mechanisms [9]. It should be noted that the relationship between the hydrophobic properties of bacterial surface and its phagocyte-stimulating ability is poorly understood. MATERIALS AND METHODSTwelve S. aureus strains isolated from patients with pyointlammatory diseases of staphylococcal etiology and identified by biological and biochemical (Staphy-