N-acetyl-β-d-glucosaminidase in the localisation of urinary tract infection in patients with spinal cord injury

Abstract

This study evaluates the pattern of urinary N-acetyl-beta-D-glucosaminidase (NAG) isoenzyme excretion in patients with spinal cord injury (SCI) and its use as a diagnostic tool in localising the site of urinary tract infection (UTI). NAG-B excretion in 27 control SCI patients (mean 207.78 units) was significantly higher than in 10 normal controls (mean 12.6 units) p less than 0.001). The relative isoenzyme distribution as represented by NAG-B/Total NAG percentage is however similar in both groups, 24.27 and 20.38% respectively. NAG-B excretion in 6 SCI patients with upper UTI was not significantly higher than in 12 SCI patients with lower UTI. NAG-B/Total NAG percentage was significantly different between these two groups (35.3% and 24.98% respectively, p less than 0.05). There was no significant difference in NAG-B excretion or NAG-B/Total NAG percentage between control SCI patients and those with lower UTI. The results indicate that there is a non-selective increase in urinary NAG excretion in control SCI patients and those with lower UTI. In SCI patients with upper urinary UTI there is a selective increase in NAG-B excretion. The overlap in enzyme values between the different groups suggests that the test may not be clinically useful in localising the site of UTI.