Teicoplanin-functionalized magnetic beads for detection of Staphylococcus aureus via inhibition of the luminol chemiluminescence by intracellular catalase

An affinity-based protocol is described for the detection of Staphylococcus aureus ( S. aureus ). It is utilizing teicoplanin-functionalized magnetic beads as carriers. Teicoplanin, which binds to the walls of cells of S. aureus via five hydrogen bonds, acts as the recognition agent. Captured S. aureus is magnetically separated from the sample matrix and then specifically lysed by lysostaphin which cleaves the cross-linking pentaglycine bridges of peptidoglycan in the cell wall. Lastly, S. aureus is quantified via the inhibitory effect of released intracellular catalase on a chemiluminescent (CL) system composed of peroxidase, luminol, H 2 O 2 and p -iodophenol because catalase decomposes H 2 O 2 . S. aureus can be detected with CL response in the 140 to 1.4 × 10 7  CFU·mL −1 concentration range and a detection limit as low as 47 CFU·mL −1 at a signal-to-noise ratio of 3. The method was evaluated by analyzing spiked samples including milk, human urine and saline injection solutions. The reliability was demonstrated by a recovery test and by comparison with a conventional plate counting method. An antibiotic-affinity protocol is developed to detect Staphylococcus aureus ( S. aureus ) by utilizing teicoplanin-functionalized magnetic beads (Teic-MBs) as carriers. S. aureus can be quantified by measuring the inhibition of luminol chemiluminescence (CL) signal by intracellular catalase.