In both types of infections, caused either by coagulase-positive or coagulase-negative Staphylococci, a marked increase was observed in the expression levels of FOS and TNF genes, and genes encoding the major histocompatibility system proteins (MHC)-BOLA-DQB, BOLA-DRB3, or BOLA-DQA1. This evidence concerns the gene FOS and infection.