Diagnosis / UTI

Specimen Collection

Specimens collected using a drainage bag or taken from a collection hat are not reliable and should not be sent.

The urethral area should be cleaned with an antiseptic cloth and the urine sample collected midstream or obtained by fresh catheterization.


Nitates indicate the presence of a nitrate reducing microorganism such as E. coli or any other member of the Enterobacteriaceae family.

Nitrates will be negative if the infection is due to a non-nitrate reducing organism such as Enterococcus.

Leukocyte esterase indicates white blodd cells in the urine.

Bacteruria: presence of bacteria on a urinalysis should be interpreted with caution and is not generally useful.

Pyuria: more sensitive than leukocyte esterase (>5-10 WBC/hpf or > 27 WBC/microliter)


If urinalysis is negative for pyuria, positive cultures are likely contamination.

Positive cultures with pyuria are defined as ≥ 100,000 colonies. This cut off is most sensitive for a true UTI. Situations in which lower colony counts may be significant include: patients who are already on antibiotics, symptomatic young women, suprapubic aspiration, and men with pyuria.