Urinary nitrite and urinary-tract infection.
Two dipstick procedures and an automated quantitative urinary nitrite assay were used to study nitrite in 786 samples of urine submitted to the bacteriology laboratory for routine culture and sensitivity testing. Many samples that had more than 100,000 nitrite-reducing organisms/ml and no detectable nitrite were studied. Limited nitrate concentration in urine was not a significant cause of false-negative nitrite results. However, in some urine samples nitrite added in vitro was lost during a four-hour incubation in vitro at 37 C in the presence of more than 100,000 nitrite-reducing organisms/ml. Ascorbic acid, abnormal amounts of urobilinogen, and urinary pH below 6.0 are all possible causes of false-negative nitrite determinations.
Urinary nitrite and urinary-tract infection. Two dipstick procedures and an automated quantitative urinary nitrite assay were used to study nitrite in 786 samples of urine submitted to the bacteriology laboratory for routine culture and sensitivity testing. Many samples that had more than 100,000 nitrite-reducing organisms/ml and no detectable nitrite were studied. Limited nitrate concentration in urine was not a significant cause of false-negative nitrite results. However, in some urine samples nitrite added in vitro was lost during a four-hour incubation in vitro at 37 C in the presence of more than 100,000 nitrite-reducing organisms/ml. Ascorbic acid, abnormal amounts of urobilinogen, and urinary pH below 6.0 are all possible causes of false-negative nitrite determinations.