Characterization of resident bacteriophages and their role in conversion of exfoliative toxin A production in <I>Staphylococcus aureus</I>
| Authors | |
|---|---|
| Year of publication | 2004 |
| Type | Article in Proceedings |
| Conference | 11th International Symposium on Staphylococci & Staphylococcal Infections. Plenary Summaries & Poster Abstracts |
| MU Faculty or unit | |
| Citation | |
| Web | http://www.isssi.org/ |
| Field | Genetics and molecular biology |
| Keywords | staphylococcus; exfoliative toxin A; bacteriophage; lysogenic conversion |
| Description | Two exfoliative toxins, ETA and ETB, produced by certain strains of S. aureus are the major causative agents of blistering skin disorders with the most severe form the Staphylococcal Scalded Skin Syndrome, primarily affecting infants and young children. The eta gene encoding ETA is located on the chromosome, whereas the etb gene encoding ETB is located on a large plasmid. Temperate bacteriophages carrying the eta gene and converting exfoliative toxin A production in S. aureus, have been recently, found. Eight bacteriophages isolated from 8 human ETA-positive strains of S. aureus by UV induction were classified into serogroups, screened for carriage of the eta gene by PCR, and characterized by HindIII restriction analysis. Three of them were used for the ETA conversion experiments. Location of prophages in lysogens was revealed by PFGE and ETA production was detected by RPLA. Five of the phages were classified into serogroup A (A-phages) and three into serogroup B (B-phages). Restriction enzyme HindIII cleavage analysis enabled us to distinguish three subtypes, A-1, A-2 and A-3, within serogroup A and two subtypes, B-1 and B-2, among serogroup B phages. PCR assay showed that all B-phages and three of five A-phages were outfitted with the structural gene for ETA. Phages, one of serogroup A and two of serogroup B, lysogenized ETA-negative S. aureus strains but only two lysogens which acquired the eta gene with B-phages were able to produce ETA. We found that the two B-phages integrated into the second largest SmaI fragment, whereas the A-phage integrated into the fourth largest SmaI fragment of the recipient strain. Human ETA-positive S. aureus strains carry prophages having their origin in phages of serogroups A, B or F. Our results indicate that the resident B-phages are mobile genetic elements that mediate the horizontal transfer of the eta gene among S. aureus strains and may have played an important role in the evolutionary processes among these pathogens. |
| Related projects: |