The ability to inhibit the opsovizing activity of immunoglobulins and the C3 component of the complement is demonstrated for Staphylococcus aureus. This ability is due to the presence of extracellular products such as the anticomplement factor and protein A. An independent and statistically significant determination of the antiopsonizing effect of these extracellular products by the given parameters is established. Key Words: staphylococci; opsonization; chemiluminescenceThe ability to suppress natural resistance of the host organism is important for prolonged survival (persistence) of microorganisms [2]. In the case of staphylococci this is achieved through disorders in opsonizing cooperation [6] that lower the effectiveness of the interaction between phagocytes and bacterial cells. The factors determining this phenomenon remain unknown. However, the ability of St. aureus to inhibit the complement system [1] in line with the evidence on a possible alternative Fc-receptor binding of immuno~obulins by protein A of these microorganisms [4] raises the question about the role of these factors in the generation of the antiopsonizing effect.Our aim was to study the mechanisms responsible for the ability of staphylococci to protect themselves against the opsonizing activity of blood serum; this protection has been related to the anticomplement factor and protein A. For this purpose we employed the method of luminol-dependent chemiluminescence (CL) of macrophages [9]. MATERIALS AND METHODSWhen the C3-mediated opsonizing effects were examined, CL was induced with zymosan (10 mg/ ; native zymosan was used as the control. The opsonizing effect of immunoglobulins was evaluated by inducing CL with heat-inactivated staphylococci (strain 209P, 1 bln. cells per ml); intact microorganisms were used as the control, and those treated with commercial preparation of human antistaphylococcal immunoglobulin (10 IU/ml) were used in the experiment. Staphylococci treated with NBS (the same object of phagocytosis) were used to reproduce the opsonizing reactions mediated by the complex of the above-mentioned factors [8]. The effect of the extracellular staphylococcal products on the effectiveness of opsonization was evaluated after contact of the supernatants of St. aureus cultures grown in liquid media with CL inducers followed by washing (3 times with a 0.85% NaC1 solution) with standardization to the initial optical density. The studied group of staphylococci included 54 strains which manifested either the anticomplement or protein A activity or varied degrees of both activities. Peritoneal macrophages were obtained by perfusing the abdominal cavity of (CBAxC57B1/6)F 1 mice with 0.85% NaC1 and purified by adhesion on glass. The cells were suspended to a final concentration of 0.5 mln. cells/ ml in Eagle's culture medium supplemented with 0.2% bovine serum albumin and 0.02 M luminol.
A relationship is found between the resistance of Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis to human serum and whole blood and their ability to inactivate the factors of natural antiinfectious resistance (lysozyme, complement, immunoglobulins, and a bactericidal fraction of leukocytic interferon).Key Words: E. coli; staphylococci; ability to inactivate natural resistance factors; resistance to serum and whole bloodThe ability to resist the lethal action of effector mechanisms of immunity confers on pathogens certain advantages for their survival in the host [1]. Gram-negative bacteria, specifically, E. coli, which are on the whole sensitive to the bactericidal effect of blood serum (BES), are nonetheless often fairly resistant and therefore capable of initiating infectious processes of some Iocalizations. This singles out BES resistance as an important factor of their virulence [13]. A different situation is observed with gram-positive microorganisms, such as staphylococci, which are commonly little sensitive to BES but are relatively effectively eliminated upon cooperative exposure to opsonins and phagocytes. Resistance to the bactericidal effect of whole blood (BEB) is the marker of their virulence in such cases [6,10].Study of the nature of these phenomena permitted us to characterize a number of morphological Orenburg Department of Microorganism Persistence, Institute of Ecology and Genetics of Microorganisms, Urals Division of the Russian Academy of Sciences structures and physiological features regulating the survival of bacteria in the presence of host bactericidal systems [11,13]. However, mechanisms directed toward inactivating the natural antiinfectious resistance factors, the principal effectors of BES and BEB, are represented by just a few examples in this series [9]. Hence, this study was aimed at ascertaining the role of a new group of bacterial properties [1] -antilysozyme and anticomplement activities, the ability to inactivate the bactericidal component of an interferon preparation (anti-BCI) of E. coli, S. aureus, and S. epidermidis, and the known capacity of S. aureus for alternative Fc reception of immunoglobulins by protein A -in rendering bacteria resistant to the lethal action of human serum and whole blood. MATERIALS AND METHODSThirty-nine uropathogenic strains of E. coil isolated from patients with pyelonephritis and 22 strains of S. epidermidis and 30 strains of S. aureus isolated from 0007-4888/96/0002-0160515.00 =1996 PLenum Pubt~sh~ng Corporation
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-
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