In house-development of a rapid immunochromatographic test for the detection of Escherichia coli in urine samples.

Urinary tract infections (UTIs) are a common health concern. Urine culture is the "gold standard" for UTI diagnosis but takes 48h. Rapid methods like dipstick tests are used as point-of-care tests. However, their sensitivity and specificity are variable. In this work, a rapid immunochromatographic test (IT) for detecting Escherichia coli in urine was developed, and its performance was evaluated in urine samples from patients with suspected UTI. The "universal lateral flow assay kit" was employed using an E. coli capture antibody. One hundred and five (105) urine samples were analyzed using the IT, dipstick test, and urine culture. The sensitivity of the IT was 74.5%, specificity 88.9%, positive predictive value (PPV) 86.3%, and negative predictive value (NPV) 78.7%. The combination of the IT with the dipstick test increases sensitivity to 94.1%, specificity to 66.7%, PPV to 72.7%, and NPV to 92.3%. Using the IT for detecting E. coli in urine could be a valuable technique for UTI screening, showing better specificity and diagnostic precision but lower sensitivity than the dipstick test. Based on these results, we propose that the combined use of both screening techniques would allow a rapid and more precise diagnosis of UTI, rationalizing the indication for empirical antibiotics.