Expression of enterotoxin-coding genes in methicillin-resistant Staphylococcus aureus strains isolated from Mexican haemodialysis patients

Abstract

Doc number: 55

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) causes severe catheter-related infections in haemodialysis patients ranging from local-site infections and septic thrombophlebitis to bacteraemia but the associated virulence factors and exotoxins remain unclear.

Findings: We employed an in vitro infection model using reconstituted human epithelium (RHE) to analyse the expression profiles of 4 virulence genes and 12 exotoxin-coding virulence genes in 21 MRSA strains isolated from catheter-related infections in 21 Mexican patients undergoing haemodialysis.

All 21 strains (100%) expressed the seg, seh, sei, eta, etb, or hla genes coding staphylococcal toxins. Eleven MRSA strains (52.3%) expressed the sea gene coding staphylococcal enterotoxin A, and two strains (9.5%) expressed the v8 gene coding serine protease. The tst , chp, and arcA genes coding toxic shock syndrome toxin 1, chemotaxis inhibitory protein, and arginine deiminase, respectively, were expressed in separate single strains (4.7%). The most frequent expression profile (42.8% of the strains) comprised seg, seh, sei, eta, etb, and hla .

Conclusion: It is likely that the SEG, SEH, SEI, ETA, ETB, and Hla toxins may play a role in MRSA catheter-related infections. Consideration of these toxins in the development of a vaccine or as targets for monoclonal antibody therapy could provide an improved therapeutic strategy for the treatment of catheter-related infections in haemodialysis patients.