Cytokine response in patients with chronic infections caused by Staphylococcus aureus strains and diversification of their Agr system classes.

This study aimed to describe the levels of circulating cytokine levels produced by Th lymphocytes (IFN-γ, IL-4, IL-10, IL-17A), as well as the levels of cytokines produced by monocytes/macrophages (TNF-α, IL-1ß, IL-12), in patients with chronic infections caused by Staphylococcus aureus strains, particularly in the context of the diversification of their Agr system classes. The studies were conducted on adult patients, including 50 patients with chronic suppurative dermatitis, 40 patients with chronic infections of the upper respiratory tract and 25 healthy individuals (control group). Blood serum cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA). S. aureus was detected in cultures of suppurative dermal exudates or of pharyngeal smears. Classes of Agr systems in the S. aureus strains were identified using polymerase chain reaction (PCR). In both groups of patients, on average, levels of IFN-γ were doubled, while levels of IL-17A were increased by 2.5-fold, which, however, was not accompanied by increased levels of TNF-α or IL-12. The data indicate that the development of S. aureus infection among the studied patients was linked to an impoverished cytokine response of monocytes/macrophages, while that induced by the pathogen lymphocytes Th17/Th1 may be responsible for promotion of the chronic inflammatory response. In parallel, no quantitative or qualitative differences were disclosed between cytokine responses manifested by subgroups of patients infected with S. aureus strains belonging to class IV Agr, as compared to patients infected with strains of classes I to III Agr. Nevertheless, in the patients, strains belonging to class IV Agr prevailed, which points to the preferential relationship between the class and the pathogenicity of S. aureus.

Antibody responses in furunculosis patients vaccinated with autologous formalin-killed Staphylococcus aureus.

Autologous vaccines (short: autovaccines) have been used since the beginning of the 20th century to treat chronic staphylococcal infections, but their mechanisms of action are still obscure. This prospective pilot study involved four patients with furunculosis who were vaccinated with autologous formalin-killed Staphylococcus aureus cells. Vaccines were individually prepared from the infecting S. aureus strain and repeatedly injected subcutaneously in increasing doses over several months. We characterized the virulence gene repertoire and spa genotype of the infecting and colonising S. aureus strains. Serum antibody responses to secreted and surface-bound bacterial antigens were determined by two-dimensional immunoblotting and flow-cytometry based assays (Luminex). All patients reported clinical improvement. Molecular characterization showed that all strains isolated from one patient over time belonged to the same S. aureus clone. Already before treatment, there was robust antibody binding to a broad range of staphylococcal antigens. Autovaccination moderately boosted the IgG response to extracellular antigens in two patients, while the antibody response of the other two patients was not affected. Similarly, vaccination moderately enhanced the antibody response against some staphylococcal surface proteins, e.g. ClfA, ClfB, SdrD and SdrE. In summary, autovaccination only slightly boosted the pre-existing serum antibody response, predominantly to bacterial surface antigens.