Developing an affordable but reliable human blood ex vivo model to analyse gene expression by Staphylococcus epidermidis

Abstract

Background: Staphylococcus epidermidis is a commensal inhabitant of healthy human skin and mucosae. However, when external barriers, such as the skin, are damaged, the bacterium gains accesses into the bloodstream and emerges as an opportunistic pathogen. S. epidermidis can originate important infections such as medical device-associated bloodstream infections. This is mainly due to its ability to attach and form biofilms on the surface of vascular catheters. Hence, due to the clinical relevance of S. epidermidis medical device-associated bloodstream infections, human blood is frequently used as an ex vivo model, to mimic the environment encountered by the bacterium and study its behavior. An important limitation in the use of human blood is the availability of donors and the considerable quantity of blood necessary. As any other biological resource, the use of blood shall be reduced to a minimum and, thus, our goal was to test the influence of different volumes of human blood on the stability of S. epidermidis gene expression and on bacterial culturability.