An Integrated Microfluidic System for Bacteria Identification from Human Joint Fluids

An integrated microfluidic system was developed to identify bacteria in human joint fluid (HJF) in this study. The entire process including bacteria isolation in HJF, bacteria lysis, polymerase chain reaction (PCR) and optical detection could be automated on a single chip. An universal 16S rRNA primer set and four designed primers to identify Staphylococcus aureus (SA), methicillin-resistance Staphylocuccus aureus (MRSA), Escherichia coli (E. coli), and Acinetobacter baumannii $(\pmb{A}.\pmb{B}.)$ were used for bacteria identification. In addition, N-acetyl-L-cysteine for dissolving sticky mucus of HJF samples and vancomycin-coated magnetic beads were applied for bacteria isolation such that the detection limit could be significantly improved. The entire process could be automated by using a microfluidic system. Experimental results showed that the limit of detection (LOD) could be significantly improved to 100 colony formation units (CFU) per milliliter (or 20 CFU/reaction), which meets the demand on clinical diagnosis. Furthermore, the whole process could be performed within 90 minutes, which is much faster when compared to the traditional method (usually 3–7 days).