The Clinical Significance of Dipstick-Negative, Culture-Positive Urines in a Veterans Population

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Abstract
The consequences of omitting cultures in dipstick-negative urines submitted to the authors’ microbiology laboratory were evaluated retrospectively in 1,079 clean-catch midstream samples. Using positive dipstick readings for leukocyte esterase, nitrite, and/or protein as evidence of a positive screen, the sensitivity, specificity, positive predictive value, and negative predictive value for specimens containing more than or 103 CFUs/mL (106/L) were 80%, 71%, 48%, and 91%, respectively. Clinical data were reviewed in 38 patients with one or more dipstick-negative, culture-positive urines. Most of these patients lacked clinical or other laboratory evidence suggesting urinary tract infection. Problems with specimen collection were suspected in 19 neurologically compromised patients. Only two patients with dipstick-negative urines received treatment based on the culture reports. Symptoms persisted in both. The authors conclude that in their predominantly male veteran population, clinically significant bacteriuria is an unlikely finding in a dipstick-negative urine.