[Show abstract][Hide abstract] ABSTRACT: Staphylococcus aureus is the major cause of surgical site infections, and meticillin-resistant S. aureus (MRSA) is increasingly accounting for infections worldwide. Preventing surgical site infections by screening and decolonising positive patients reduces the number of infections, but does not completely eradicate the risk. A balance between prevention, costs and the chance of mupirocin-resistant S. aureus needs to be evaluated and decolonisation strategies optimised. It is essential to know the site of S. aureus during colonisation. In this study, for the first time the exact location of S. aureus in the human nose was determined using a histological approach. We showed the presence of S. aureus in the cornified layer of squamous epithelium, associated keratin and mucous debris and within hair follicles in the vestibulum nasi. The presence of S. aureus in hair follicles suggests that this could be the niche from which relapses occur after decolonisation. Decolonisation strategies might have to be reconsidered.
The Journal of hospital infection 11/2010; 76(3):211-4. · 3.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In bacteria, gene regulation is one of the fundamental characteristics of survival, colonization and pathogenesis. Operons play a key role in regulating expression of diverse genes involved in metabolism and virulence. However, operon structures in pathogenic bacteria have been determined only by in silico approaches that are dependent on factors such as intergenic distances and terminator/promoter sequences. Knowledge of operon structures is crucial to fully understand the pathophysiology of infections. Presently, transcriptome data obtained from growth curves in a defined medium were used to predict operons in Staphylococcus aureus. This unbiased approach and the use of five highly reproducible biological replicates resulted in 93.5% significantly regulated genes. These data, combined with Pearson's correlation coefficients of the transcriptional profiles, enabled us to accurately compile 93% of the genome in operon structures. A total of 1640 genes of different functional classes were identified in operons. Interestingly, we found several operons containing virulence genes and showed synergistic effects for two complement convertase inhibitors transcribed in one operon. This is the first experimental approach to fully identify operon structures in S. aureus. It forms the basis for further in vitro regulation studies that will profoundly advance the understanding of bacterial pathophysiology in vivo.
Nucleic Acids Research 02/2010; 38(10):3263-74. · 8.81 Impact Factor