Direct Blood Culturing of Candida spp. on Solid Medium by a Rapid Enrichment Method with Magnetic Beads Coated with Recombinant Human Mannan-Binding Lectin

Abstract

A rapid and accurate method to identify the species and antibiotic resistance of Candida spp. in blood is vital to increase the survival rates of patients with bloodstream infections. However, the extremely low levels of Candida spp. in blood make rapid diagnosis by standard blood culture difficult. In this study, we constructed a direct blood culturing method (i.e., the M1 method) by a rapid enrichment method with magnetic beads coated with a recombined human mannan-binding lectin (rhMBL; i.e., M1 protein), which demonstrated much higher Candida sp.-binding capacity than that of full-length MBL expressed in vitro (i.e., M2). With the M1 method, individual colonies were obtained before the standard blood culture method for each species of Candida spp. tested at <1 CFU/ml (an average of 29 h earlier). Additionally, the clinical sensitivity of the M1 method was 90.5% compared with that of the standard blood culture method when detecting frozen plasma from patients. More significantly, the turnaround time of the M1 method for blood culture could be reduced by approximately 37 to 43 h compared with that of the standard blood culture method in clinical sample identification.

Detection of low-load Epstein-Barr virus in blood samples by enriched recombinase aided amplification assay

“…Compared with the traditional culture method, it has been shown that after enrichment with magnetic beads, bacteria can be detected several hours or even several days earlier. In contrast to most studies, we did not use specific antibodies to capture a specific pathogen but instead used M1 protein to non-specifically capture pathogens with an M1 protein binding site from the blood (Chen et al 2020 ). In addition, in the subsequent nucleic acid amplification stage, we used a rapid RAA isothermal amplification assay.…”

“…The M1 protein was supplied by the Nosocomial Infection Laboratory of the National Institute for Communicable Disease Control Prevention, Chinese Center for Disease Control and Prevention (Chen et al 2020 ). The protein concentration was determined and frozen at −80℃.…”

“…Finally, the complexes were re-suspended in 100 μL PBS (1×) solution. The prepared M1 beads were stored at 4℃ for up to 14 days (Chen et al 2020 ).…”

“…To overcome these drawbacks, we have developed an EBV detection method that combines RAA with an initial EBV separation and enrichment step using magnetic beads coated with a recombinant human mannan-binding lectin (rhMBL, M1 protein) (Chen et al 2020 ). To facilitate EBV separation and enrichment, we coupled the protein A-coated magnetic microspheres with M1 protein for non-specific capture of EBV from a large sample volume of blood (1.5 mL).…”

Detection of Saccharothrix spp. in the blood of two immunocompromised patients

“…During his hospitalization, three standard blood cultures with BacT/ALERT3D60 system (bioMé rieux, France) were all negative. Direct culture with M1 beads enrichment was performed as described previously (1). Small colonies were grown on agar plate.…”