Accuracy of diagnostic tests to detect asymptomatic bacteriuria during pregnancy.

Abstract

OBJECTIVE:

A dipslide is a plastic paddle coated with agar that is attached to a plastic cap that screws onto a sterile plastic vial. Our objective was to estimate the diagnostic accuracy of the dipslide culture technique to detect asymptomatic bacteriuria during pregnancy and to evaluate the accuracy of nitrate and leucocyte esterase dipslides for screening.

METHODS:

This was an ancillary study within a trial comparing single-day with 7-day therapy in treating asymptomatic bacteriuria. Clean-catch midstream samples were collected from pregnant women seeking routine care. Positive and negative likelihood ratios and sensitivity and specificity for the culture-based dipslide to detect and chemical dipsticks (nitrites, leukocyte esterase, or both) to screen were estimated using traditional urine culture as the "gold standard."

RESULTS:

: A total of 3,048 eligible pregnant women were screened. The prevalence of asymptomatic bacteriuria was 15%, with Escherichia coli the most prevalent organism. The likelihood ratio for detecting asymptomatic bacteriuria with a positive dipslide test was 225 (95% confidence interval [CI] 113-449), increasing the probability of asymptomatic bacteriuria to 98%; the likelihood ratio for a negative dipslide test was 0.02 (95% CI 0.01-0.05), reducing the probability of bacteriuria to less than 1%. The positive likelihood ratio of leukocyte esterase and nitrite dipsticks (when both or either one was positive) was 6.95 (95% CI 5.80-8.33), increasing the probability of bacteriuria to only 54%; the negative likelihood ratio was 0.50 (95% CI 0.45-0.57), reducing the probability to 8%.

CONCLUSION:

A pregnant woman with a positive dipslide test is very likely to have a definitive diagnosis of asymptomatic bacteriuria, whereas a negative result effectively rules out the presence of bacteriuria. Dipsticks that measure nitrites and leukocyte esterase have low sensitivity for use in screening for asymptomatic bacteriuria during gestation.

CLINICAL TRIAL REGISTRATION:

ISRCTN, isrctn.org, 1196608

LEVEL OF EVIDENCE:

II.

• Authors: Luciano Mignini, Guillermo Carroli, Edgardo Abalos, Mariana Widmer, Susana Amigot, Juan Manuel Nardin, Daniel Giordano, Mario Merialdi, Graciela Arciero, Maria Del Carmen Hourquescos, World Health Organization Asymptomatic Bacteriuria Trial Group
• Journal: Obstetrics and gynecology (Obstet Gynecol) Vol. 113 Issue 2 Pt 1 Pg. 346-52 (Feb 2009) ISSN: 0029-7844 [Print] United States
• PMID: 19155905 (Publication Type: Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Nitrites
• Reagent Kits, Diagnostic
• leukocyte esterase
• Carboxylic Ester Hydrolases

Topics

• Bacteriuria (diagnosis)
• Carboxylic Ester Hydrolases (urine)
• Colony Count, Microbial
• Female
• Humans
• Likelihood Functions
• Nitrites (urine)
• Predictive Value of Tests
• Pregnancy
• Pregnancy Complications, Infectious (diagnosis)
• Reagent Kits, Diagnostic
• Urinalysis
• World Health Organization