Comparative immunochemical characteristics of extracellular polysaccharide-containing preparations and teichoic acids of Staphylococcus aureus

The sensitivity of the enzyme immunoassay on the basis of polysaccharide-containing preparations was found to be lower than that of the assay on the basis of teichoic acids. The specificity of both assays was 100%. There was no complete coincidence between the results of the detection of antibodies to these two antigens in patients' sera.     

Genome of Staphylococcus xylosus and Comparison with S.aureus and S.epidermidis

Staphylococci are Gram-positive, AT-rich cocci, and often stick together in grape-like clusters. The genus can be classified into two groups based on their ability to produce coagulase, an enzyme that causes clotting of blood plasma （Otto, 2004）. Coagulase-positive Staphylococci include Staphylococcus aureus, a common pathogen of community-acquired and nosocomial infections （Smith et al., 2009）.     

ChemicaL and immunochemical characteristics of antigenic preparations from Staphylococcus aureus and Klebsiella pneumoniae as the components for an associated vaccine

S. aureus aqueous extract and K. pneumoniae hydroxylamine vaccine were studied by means of chemical and immunochemical analytical techniques. The preparations were found to contain, respectively, 7.0% nad 53.5% of neutral monosaccharides, 6.5% and 0.7% of nucleic acids, as well as protein in approximately equal amounts (11.63-14.0%). In experiment of immunodiffusion, immunoelectrophoresis and rocket immunoelectrophoresis in homologous systems with hyperimmune antimicrobial sera the preparations were characterized by serological heterogeneity. After their combination with Escherichia coli aqueous extract and Proteus hydroxylamine preparation their serological characteristics remaIned unchanged. The study of cross reactions of all components of the combined preparations with hyperimmune rabbit sera to the corresponding microorganisms revealed that only Klebsiella component of the combined vaccine reacted with all hyperimmune sera. The preparation of Proteus showed the lowest activity, it reacted only with hyperimmune sera to K. pneumoniae. Besides, no reaction of S. aureus component with sera to E. coli and no reaction of the preparation of E. coli with antistaphylococcal serum were observed.     

Drug resistance and pathogenicity of S. aureus isolated from patients

Over the period 1983-1985, investigators from the Institute of Hygiene and Epidemiology, Prague, and the Central Research Institute of Epidemiology, USSR Ministry of Public Health, Moscow, carried out a joint study of drug resistance in S. aureus strains in relation to their enterotoxigenic properties and phage group specificity. Altogether 277 strains were explored which had been isolated at random from the clinical material from infant and adult inpatients. Most of the isolated strains featured multiple resistance to antibiotics: PNC (77.9%), CMP (52.7%), TET (21.6%), ERY (17.6%) and LIN (11.9%). The strains isolated from infants were most frequently resistant to TET and ERY. No correlation was found between the incidence of antimicrobial drugs resistance and toxigenic properties of the isolated strains.     

Intranasal application of S. epidermidis prevents colonization by methicillin-resistant Staphylococcus aureus in mice

Methicillin-resistant S. aureus emerged in recent decades to become a leading cause of infection worldwide. Colonization with MRSA predisposes to infection and facilitates transmission of the pathogen; however, available regimens are ineffective at preventing MRSA colonization. Studies of human nasal flora suggest that resident bacteria play a critical role in limiting S. aureus growth, and prompted us to query whether application of commensal resident bacteria could prevent nasal colonization with MRSA. We established a murine model system to study this question, and showed that mice nasally pre-colonized with S. epidermidis became more resistant to colonization with MRSA. Our study suggests that application of commensal bacteria with antibiotics could represent a more effective strategy to prevent MRSA colonization.     

The antigenic structure of ferritin. 1. Isolation of ferritin subunits and their immunochemical characteristics]

A method for the isolation of monomers of ferritin subunits has been developed. The procedure comprises dissociation of ferritin by treatment with thioglycolic acid in the presence of phosphate ions and subsequent gel-permeation chromatography. Ferritin and a number of its structural analogues (apoferritin, carboxymethylated ferritin, H- and L-subunits of ferritin) have been immunochemically characterized. The immunoreactivity of ferritin is shown to vary along with the degree of denaturation. Isolation of monomers of H- and L-subunits results in appearance of new antigenic sites. These "hidden" antigenic determinants are presumed to be localized in the regions of intersubunit contacts and intracapsular surface of the ferritin molecule and are responsible for the differences in immunochemical properties of its H- and L-subunits.     

Slime-producing Staphylococcus epidermidis and S. aureus in acute bacterial conjunctivitis in soft contact lens wearers

In recent years, an increase in ocular pathologies related to soft contact lens has been observed. The most common infectious agents were Staphylococcus spp. Some strains produce an extracellular polysaccharidic slime that can cause severe infections. Polysaccharide synthesis is under genetic control and involves a specific intercellular adhesion (ica) locus, in particular, icaA and icaD genes. Conjunctival swabs from 97 patients with presumably bacterial bilateral conjunctivitis, wearers of soft contact lenses were examined. We determined the ability of staphylococci to produce slime, relating it to the presence of icaA and icaD genes. We also investigated the antibiotic susceptibility and Pulsed Field Gel Electrophoresis (PFGE) patterns of the clinical isolates. We found that 74.1% of the S. epidermidis strains and 61.1% of the S. aureus strains isolated were slime producers and showed icaA and icaD genes. Both S. epidermidis and S. aureus slime-producing strains exhibited more surface hydrophobicity than non-producing slime strains. The PFGE patterns overlapped in S. epidermidis strains with high hydrophobicity. The similar PFGE patterns were not related to biofilm production. We found scarce matching among the Staphylococcus spp. studied, slime production, surface hydrophobicity and antibiotic susceptibility.