RESUMO
Western blotting of whole-cell preparations of Enterococcus faecalis showed the protein-antigen profiles to be markedly influenced by growth conditions. The E. faecalis-specific antigens of 40 and 37 kDa, which are prominent in endocarditis, were strongly expressed following growth in serum or brain heart infusion, but not after growth in a chemically defined medium. The expression of these antigens in vivo was demonstrated in cells grown as a biofilm on silastic discs in the peritoneum of rabbits. These in vivo culture conditions may be useful in studying the pathogenesis of E. faecalis infections and the effectiveness of antibiotic therapy.
Assuntos
Antígenos de Bactérias/biossíntese , Enterococcus faecalis/imunologia , Animais , Antígenos de Superfície/biossíntese , Sangue , Western Blotting , Meios de Cultura , Enterococcus faecalis/crescimento & desenvolvimento , Humanos , CoelhosRESUMO
Enterococcus (Streptococcus) faecalis expresses three species-specific surface protein antigens of molecular weights 73,000, 40,000, and 37,000. On Western blotting (immunoblotting), they were detected strongly by immunoglobulin G (IgG) in sera from patients with E. faecalis endocarditis, but not in sera from patients with other E. faecalis infections or with endocarditis due to other streptococci. We developed an enzyme-linked immunosorbent assay system to measure IgG, IgM, and IgA levels to these antigens and evaluated its potential as a serodiagnostic test for E. faecalis endocarditis. The test correctly diagnosed E. faecalis endocarditis in 15 of 16 cases. Of 10 cases of endocarditis due to other streptococci and 10 E. faecalis infections other than endocarditis, 9 and 8, respectively, gave negative results. The test should prove particularly useful in culture-negative cases, for which choice of appropriate antibiotic therapy for E. faecalis endocarditis is vital.
Assuntos
Anticorpos Antibacterianos/análise , Endocardite Bacteriana/imunologia , Ensaio de Imunoadsorção Enzimática , Infecções Estreptocócicas/imunologia , Antígenos de Bactérias/isolamento & purificação , Meios de Cultura , Endocardite Bacteriana/diagnóstico , Enterococcus faecalis/imunologia , Estudos de Avaliação como Assunto , Humanos , Imunoglobulina A/análise , Imunoglobulina G/análise , Imunoglobulina M/análise , Peso Molecular , Testes Sorológicos , Infecções Estreptocócicas/diagnósticoRESUMO
Binding of human fibronectin (FN) and albumin to Enterococcus (Streptococcus) faecalis was investigated. Scatchard analysis showed that the cells could bind a maximum of 1300 molecules of FN with an association constant of 4.8 x 10(6) M-1. Binding did not appear to involve lipoteichoic acid. Heating the cells or pretreatment with protease or periodate reduced the binding, suggesting the involvement of protein and/or carbohydrate-containing components as the surface receptor. The cells could bind a maximum of 50,000 molecules of albumin but with a much lower affinity than FN (association constant 10.8 x 10(3) M-1). Surface hydrophobicity of E. faecalis was markedly decreased by albumin but not by FN.
