title: Are true-negative nitrite results affected by a two-hour delay in dipstick/pad analysis of urine in incontinence pads?
abstract: OBJECTIVE
  To determine if true-negative nitrite results of a urine dipstick pressed into an incontinence pad (dipstick/pad method) are affected by a 2-hour delay in analysis.
  
  
  METHODS
  A quantitative study.
  
  
  METHODS
  Clean-catch urine specimens from a convenience sample of clinic patients, staff, and long-term care facility residents.
  
  
  METHODS
  Changes from negative to positive for each group of urine specimens were evaluated using percentages within the groups.
  
  
  METHODS
  Urine specimens were collected and a portion was cultured. Urine specimens negative for a urinary tract infection were included in the study. A portion of the specimen was poured into an incontinence pad. Initial nitrite results were determined using a dipstick pressed into an incontinence pad. Pads with true-negative dipstick/pad nitrite results were tested 2 hours later in the same manner. Urine culture results determined groups: mixed colonies; 50,000 to 75,000 colony-forming units per milliliter of a single type of uropathogen; greater than or equal to 50,000 cfu/mL diphtheroids; no significant growth; and no growth.
  
  
  RESULTS
  Of the 443 urine cultures negative for a urinary tract infection, 441 initial dipstick/pad nitrite results were negative. Two initial true-negative nitrite dipstick/pad results, or 0.5%, changed from negative to positive over the 2-hour period: 1 in the "mixed colonies" group (0.4%) and 1 in the "no growth" group (0.7%).
  
  
  CONCLUSIONS
  Results of this study indicate that true-negative nitrite results of a dipstick pressed into urine in an incontinence pad do not appear to be affected by a 2-hour delay in analysis.
authors.affiliation: University of North Dakota, School of Medicine and Health Sciences Office of Continuing Medical Education and Outreach, USA. midthuns@gmail.com
authors.forename: Susan
authors.initials: S
authors.lastname: Midthun
authors.forename: A Wayne
authors.initials: AW
authors.lastname: Bruce
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001437:Bacteriuria / Q000175:diagnosis* / Q000382:microbiology / Q000652:urine; D015982:Bias; D015400:Clinical Nursing Research; D002985:Clinical Protocols / Q000592:standards; D015169:Colony Count, Microbial; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016496:Incontinence Pads; D008297:Male; D008875:Middle Aged; D009573:Nitrites / Q000032:analysis*; D011934:Reagent Strips / Q000592:standards; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods* / Q000451:nursing / Q000592:standards; D013997:Time Factors; D016482:Urinalysis / Q000379:methods* / Q000451:nursing / Q000592:standards
chemical_list: D009573:Nitrites; D011934:Reagent Strips