Nitrites, urinalysis

None of the exposures produced changes in clinical chemistry values (blood count, blood nitrate, blood urea nitrogen, serum enzymes, and serum electrolytes or urinalysis and nitrate and nitrite urinary excretion), spontaneous electrical activity of the cortex of the brain (detected by EEG), pulse rate and sinus rhythm, or pulmonary function. Visual and auditory acuity, exercise EKG, and time estimation tests did not differ from control values for any of the exposures. Only one of several cognitive tests was affected by exposure and the change occurred only in the four subjects exposed at 1.5 ppm. The test was taken during the time the subjects were experiencing severe headaches. 

However, a small study of younger women (16-59 years of age) presenting with a history of two symptoms - dysuria and frequency - but dipstick negative for both leucocyte esterase and nitrites, demonstrated that treatment with short-course trimethoprim significantly decreased the median time to resolution of dysuria (76% of women in trimethoprim group were free of dysuria by day 3 compared with 26% of placebo group). The authors concluded that their results supported the use of symptoms alone to diagnose and treat UTI without urinalysis (Richards et al., 2005). 

Importantly, cultures of specimens from purportedly infected sites that are obtained by sampling from or through one of these contaminated areas may contain significant numbers of the normal flora. In the case of urine cultures, the urinalysis should be used in combination with culture results to assess the presence of WBCs, nitrite, and leukocyte esterase to help confirm infection and rule out colonization. 

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