Enzymatic assay of D-mannose from urine | Bioanalysis

Aim: Urinary tract infections (UTIs) are increasingly antibiotic resistant, and alternate or adjunct therapies are urgently needed. Several studies suggest that D-mannose ingestion and a hypothesized increase in urinary D-mannose reduce UTI frequency. Our goal was to develop a reliable assay for urinary D-mannose, which is needed to assess the effects of supplemental D-mannose on urinary D-mannose and UTIs. Results: We developed an enzymatic assay for D-mannose in urine. Hexoses in urine were phosphorylated, sequentially isomerized and oxidized, and the increases in reduced NADPH were measured in a spectrophotometer. Urinary mannose from ten volunteers was well above the detection limit and ranged from 8 to 700 μM. Conclusion: A rapid, reliable, and sensitive assay was developed, readily detected urinary D-mannose, and is adaptable to high-throughput analysis. If urinary D-mannose is shown to correlate with susceptibility to UTIs, then the assay could assess susceptibility to UTIs and direct mannose therapy.