Rapid Analysis of Bacterial Contamination in Platelets without Pre-Enrichment Using Pig Serum-Derived Antibodies

As the shelf life of platelets collected from donated blood is very short, approximately 5 days, the determination of bacterial contamination in platelets has become necessary. In this study, rapid analysis of Gram-positive and Gram-negative bacterial contamination in platelet samples was presented without pre-enrichment using pig serum-derived antibodies against the outer membrane proteins (OMP) of Gram-negative bacteria and antibodies against lipoteichoic acid (LTA) on the surface of Gram-positive bacteria. The anti-OMP antibodies against Gram-negative bacteria were isolated using sequential incubation with (1) the modified Gram-negative bacteria ClearColi, which lacks lipopolysaccharide (LPS) on the outer membrane, and (2) the Gram-positive bacteria Bacillus subtilis to filter away nonspecifically bound proteins from ClearColi. The anti-lipoteichoic acid (LTA) antibodies against Gram-positive bacteria were isolated using sequential incubation with (1) the Gram-positive bacteria B. subtilis and (2) the Gram-negative bacteria Escherichia coli BL21 to filter away nonspecifically bound proteins from B. subtilis . The feasibility of using the antibodies isolated from pig serum against Gram-negative and Gram-positive bacteria was demonstrated using flow cytometry. Finally, detection of the contamination of platelets with Gram-negative and Gram-positive bacteria using the impedance immunosensor based on these isolated antibodies was successfully demonstrated.