Involvement of soil bacteria in ABO blood mistyping

• A total of 380 bacterial strains were isolated from soil samples using human blood agar.
• Thirteen strains possessed α-galactosidase activity.
• 16S rRNA sequence analysis revealed a close relatedness to the genus Bacillus.
• Indirect competitive ELISA confirmed seven strains showed type B antigen degradation.
• Particular attention should be paid to the conversion of type B to O.

The current study investigated whether ABO blood mistyping of human biological samples is induced by soil bacteria. A total of 380 bacterial strains were isolated from 50 discrete soil samples using human blood agar, and glycosidase activity evaluated for all strains using 4-nitropheny glycosides (4-nitrophenyl n-acetyl-α-d-galactosaminide, 4-nitrophenyl-α-d-galactopyranoside, 4-nitrophenyl-α-l-fucopyranoside) as substrates. Thirteen strains possessed α-galactosidase activity, and 16S rRNA sequence analysis revealed a close relatedness to the genus Bacillus. An indirect competitive enzyme-linked immunosorbent assay confirmed seven strains exhibited type B antigen degradation activity. These results demonstrated that 1.8% of the bacteria isolated from soil, were Bacillus sp., possessed galactosidase activity, and had the potential to cause ABO blood mistyping.