Development of microfluidic cartridge for culture-free detection of Staphylococcus aureus in blood

Rapid detection of small amounts of Staphylococcus aureus (S. aureus) in whole blood and the corresponding diagnosis of S. aureus is a complicated and time-consuming process. Gold standard is to culture and grow bacteria before detection, which typically takes several days and requires skilled personnel. Here, we developed a microfluidic cartridge for the culture-free isolation of S. aureus in blood and diagnosed them using a multiplex polymerase chain reaction (PCR) method. Isolation of S. aureus was achieved from large volumes of blood (typically of the order of 5 ml) using Apolipoprotein H coated magnetic beads followed by ultrasonication, a similar kind of agitation utilized in an ultrasonic bath, to lyse the enriched bacteria. The designed cartridge consisted of a rotary valve to control the sample flow and, also to direct the samples to the designated chambers for the pre-processing and bacteria isolation. By comparing PCR results from batch process and cartridge based method, we proved that the current cartridge design was capable of S. aureus detection in whole blood sample. (paper)