Expression data from clinical S. aureus strains

Microarray hybridization analysis was conducted to identify genes that may affect biofilm formation. Isolates from the 50 clinical isolates, two from LSG (strain number 2 and 7) and two from HSG donors (strain number 10 and 33) were selected. We monitored relative mRNA abundance in the four clinical S. aureus isolates using the Genechip S. aureus Genome Array (GeneChip Expression, Affymetrix, Inc., USA) to study the patterns of gene expression. The arrays contain probe sets corresponding to more than 3,300 S. aureus ORFs. Additionally, they contain probes to detect RNA of either forward or reverse orientation from more than 4,800 intergenic regions. In total, 107 were used as a control to verify the test results. A total of 432 probes on the microarrays overlapped between ORFs and intergenic regions. Two samples from each strains were used for the microarray and two independent experiments were performed.