Employment of teicoplanin-coated magnetic particles for quantifying gram-positive bacteria via catalase-catalyzed hydrolysis reaction of HO.

Based on the specific affinity behavior of teicoplanin towards Gram-positive (G) bacteria, teicoplanin-coated magnetic particles were employed to separate G bacteria. Moreover, intracellular catalase released by catalase-positive bacteria led to catalyzed hydrolysis of HO and inhibition of chemiluminescent signal of luminol-HO system. By combining the separation capability of teicoplanin-coated magnetic particles and the inhibition of luminol chemiluminescence by catalase, a facile method was proposed for quantifying catalase-positive G bacteria. In this proof-of-principle work, Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus were adopted as model bacteria to evaluate its quantification performance. The three bacteria were quantified within the dynamic ranges of 5.0 × 10-5.0 × 10 CFU mL, 4.0 × 10-4.0 × 10 CFU mL and 2.0 × 10-2.0 × 10 CFU mL, with detection limits of 156 CFU mL, 86 CFU mL and 44 CFU mL, respectively. Gram-negative bacteria and catalase-negative G bacteria both displayed minor interference. The results for quantifying bacteria in milk, human urine and physiological saline samples demonstrated its reliability for real application. It provided a promising technique tool for food safety, medical diagnosis as well as drug quality control.