Sepsis caused by gram positive and gram negative bacteria is the leading cause of death in noncoronary ICUs and the tenth leading cause of death in the United States. We have developed a microfluidic sample preparation platform for rapid on-chip detection of infectious organisms for point-of-care diagnostics. The microfluidic chips are made of a robust thermoplastic and can be easily multiplexed for high throughput applications. Bacteria are lysed on-chip via hybrid chemical/mechanical method. Once lysed, the bacterial DNA is isolated using a microscale silica bead/polymer composite solid-phase-extraction (SPE) column. Lysis was confirmed using off-chip real time PCR. We isolated and detected both gram-negative (Escherichia coli) and gram-positive (Bacillussubtilis and Enterococcus faecalis) bacterial genomic DNA from microliter scale spiked whole human blood samples. The system performs better for gram-negative bacteria than it does for gram-positive bacteria, with limits of detection at 10(2) CFU/ml and 10(3)-10(4) CFU/ml, respectively. Total extraction times are less than one hour and can be further decreased by altering the channel geometry and pumping configuration.

Silica impregnated polymer monolithic columns may provide a simple method for lysing and extracting DNA from bacteria inside of microfluidic chips. Here we use Escherichia coli as a test organism for a point of care thermoplastic microfluidic module designed to take in a urine sample, mix it with lysis buffer, and perform a hybrid chemical/mechanical lysis and solid phase extraction of nucleic acids from the sample. To demonstrate proof-of-concept, we doped human hematuric urine samples with E. coli at concentrations ranging from 101–105 colony-forming units/mL (CFU/mL) to simulate patient samples. We then performed on-chip lysis and DNA extraction. The bacterial DNA was amplified using real-time PCR demonstrating lysis and isolation down to 101 CFU/mL. Results were comparable to a commercial kit at higher concen trations and performed better at recovering DNA at lower concentrations.