Co-elimination of mec and spa genes in Staphylococcus aureus and the effect of agr and protein A production on bacterial adherence to cell monolayers

• Published in: Journal of medical microbiology Vol. 39; no. 6; pp. 422 - 428
• Main Authors: Poston, S. M, Glancey, G. R, Wyatt, J. E, Hogan, T, Foster, T. J
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.12.1993; Society for General Microbiology
• Subjects: Animals; Bacterial Adhesion - genetics; Bacteriology; Biological and medical sciences; Blotting, Southern; Blotting, Western; Cell Line; Cells, Cultured; DNA, Bacterial - analysis; DNA, Bacterial - chemistry; Epithelial Cells; Epithelium - microbiology; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genes, Regulator - genetics; Humans; Immunoglobulin G - immunology; Methicillin Resistance - genetics; Microbiology; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Reproducibility of Results; Sequence Homology, Nucleic Acid; Staphylococcal Protein A - biosynthesis; Staphylococcal Protein A - genetics; Staphylococcus aureus - genetics; Staphylococcus aureus - metabolism; Vero Cells; Staphylococcus aureus; Human; Cell culture; Mesothelium; Monkey; Protein A; Adhesion; Kidney; Abdomen; Resistance; Vertebrata; Mammalia; Infectivity; Primates; Bacteria; Micrococcales; Micrococcaceae; Larynx; Staphylococcus aureus
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/00222615-39-6-422

Department of Microbiology, UMDS, Guy's Medical School * Renal Unit, UMDS, Guy's Hospital, London Bridge SE1 9RT Department of Microbiology, Moyne Institute, Trinity College, Dublin 2 Received September 24, 1992 Revision received May 18, 1993. Accepted May 18, 1993 Phenotypic loss of protein A production was tested in six methicillin-resistant (Mc R ) Staphylococcus aureus (MRSA) isolates and their isogenic methicillin-sensitive (Mc S ) variants by a radiolabelled IgG-binding assay with washed cells and by Western blotting of supernates prepared from lysed washed cells. Genomic DNA was probed for homology with the protein A gene (spa) in Eco RI digests and for homology to the methicillin resistance gene (mec) in Hind III digests. The Mc S variants had lost homology with mec . An isogenic pair of Mc R and Mc S strains, and derivatives of S. aureus 8325-4 with site-specific mutations of the accessory gene regulator locus (agr) and spa, were tested for adherence to human peritoneal mesothelial cells in monolayer culture. The isogenic pair were also tested for adherence to HEp-2 and Vero cell monolayers in assays with 3 H thymidine-labelled bacteria. Mc R isolates produced protein A which was absent from three strains that had become Mc S . This correlated with deletion of the spa locus. Spa homology, but reduced production of protein A, was retained in one Mc S strain which also showed reduced adherence to HEp-2, Vero and mesothelial cells (p < 0·05) compared with the parent Mc R strain. A spa mutation in strain 8325-4 did not significantly affect adherence to mesothelial cells but mutation in agr increased adherence significantly in both Spa + and Spa - strains.