The uristatin dipstick is useful in distinguishing upper respiratory from urinary tract infections.

BACKGROUND

We determined the diagnostic value of the trypsin inhibitor, uristatin, that is commonly found in urine and plasma in patients with infections or inflammations of any kind.

METHODS

We collected urine specimens from patients with infections of the urinary or upper respiratory tract and from healthy controls. We also collected blood from patients with a likely upper respiratory tract infection and healthy controls. A bacterial count of >10(5) organisms/ml in urine was considered to represent infection rather than contamination.

RESULTS

The uristatin dipstick test in urine showed acceptable negative predictive values (NPV of up to 93%) for patients without infection or inflammation. Here, the dipsticks could eliminate some urine cultures. For those with infection or inflammation, the positive predictive values (PPV) of the dipsticks were lower (up to 57%). Including the leukocyte esterase and nitrite values increased the PPV of the dipsticks for those with disease.

CONCLUSIONS

The uristatin strip was more accurate than the leukocyte and nitrite dipsticks for predicting upper respiratory infections (URI) and C-reactive protein for those with infection or inflammation. The uristatin dipstick was able to detect both the bikunin and uristatin inhibitors.