The prevalence of positive urine dipstick testing and urine culture in the asymptomatic pregnant woman: A cross-sectional study

Asymptomatic bacteriuria screening for developing countries using a modified water quality test kit

Between 2% and 15% of pregnant women unknowingly experience asymptomatic bacteriuria (ASB), defined as ≥105 CFU per milliliter of urine in the absence of symptoms. ASB increases the risk of adverse pregnancy outcomes including pyelonephritis, preterm labor, and low-birth weight infants. While pregnant women in the United States are routinely screened for ASB, those in developing countries with limited resources and funding lack an accurate mechanism for ASB screening. Aquagenx water quality test kits detect Escherichia coli, the most common causative agent of ASB, and total coliform bacteria in drinking water via colorimetric and fluorescent indicators. We found that the Aquagenx system is compatible with human urine and then proceeded to develop an ASB screening protocol using disposable inoculating loops. Our protocol diagnosed artificial ASB- samples (104 CFU/mL E. coli) with a false positive (FP) rate of 33% (n = 18) and ASB+ (105 CFU/mL E. coli) with a false negative (FN) rate of 5.6% (n = 18). Clinical sample testing with our protocol revealed a FP rate of 0% in ASB- samples (n = 28) and a FN rate of 0% in ASB+ samples caused by coliforms (n = 13). Aquagenx did not detect ASB in nine clinical samples with non-coliform etiological agents due to the limitations of the technology. However, with very high accuracy for detection of E. coli and other causative agents that collectively account for 90.1% of ASB cases, these kits could be used as a diagnostic ASB screening tool in developing countries in which there is currently no alternative to urine culture.IMPORTANCEAsymptomatic bacteriuria (ASB) affects 2%-15% of pregnant women and can result in adverse maternal and fetal outcomes if left undetected and untreated. In the United States and other developed nations, pregnant women are regularly screened for ASB via urine culture. However, in low-resource countries where bacterial culture is not available, dipstick testing is used. Although accurate in cases of symptomatic bacteriuria, dipstick detection is ineffective for detecting ASB. Here, we made use of an existing water quality field test for ASB urine screening, which would be readily deployable in low-resource settings. We optimized a dilution protocol for sampling patient urine within the detection limits of the Aquagenx kit technology. Overall, we were able to detect ASB samples with Gram-negative pathogens that collectively account for 90% of all ASB cases. Utilization of this repurposed technology for proactive medical screening may help prevent adverse pregnancy and birth outcomes due to ASB.

Advances in the Treatment of Urinary Tract Infection and Bacteriuria in Pregnancy

Understanding the management of asymptomatic bacteriuria (ASB) and urinary tract infection (UTI) during pregnancy is important, given the prevalence of these conditions, associated risks to the mother and fetus /newborn, and potential requirement for antibiotic treatment. Screening for ASB with a urine culture is required during pregnancy, and a positive culture is treated for 5 to 7 days with culture-specific antibiotics. Recent research on non-antibiotic prevention and shortened duration of antibiotic treatment may offer a slightly different approach to ASB and UTI in pregnancy.

Implementation of an algorithm for testing, diagnosis, and antibiotic stewardship of asymptomatic bacteriuria in pregnancy

BACKGROUND

Asymptomatic bacteriuria affects 2% to 15% of pregnant women, with 20% to 40% developing symptoms later. Symptomatic urinary tract infections are more common in pregnancy, with a prevalence of 33%, posing risks, such as preterm delivery, low birthweight, and maternal pyelonephritis. The gold standard for urinary tract infection detection is a urine culture, but point-of-care urinalysis dipsticks are frequently performed as screens during regular obstetrical visits. Leukocyte esterase has been used to justify the treatment of asymptomatic bacteriuria, even with low sensitivity and specificity. Confirmatory tests are crucial for avoiding false positives and ensuring optimal outcomes. Current guidelines for urinalysis dipstick interpretation and the decision to treat asymptomatic bacteriuria in pregnancy are limited. It remains unclear whether an evidence-based algorithm can improve test utilization, diagnosis, and treatment decisions for asymptomatic bacteriuria in pregnancy.

OBJECTIVE

The primary objective of our study was to develop, implement, and evaluate an evidence-based algorithm to guide urinalysis interpretation, culture, diagnosis, and antibiotic stewardship of asymptomatic bacteriuria in pregnant patients during routine obstetric visits.

STUDY DESIGN

The project involves both retrospective and quasi-experimental prospective medical record reviews of pregnant patients aged ≥18 years, beyond 20 weeks of gestation, from routine obstetrical visits with urinalysis dipstick tests. A doctorate in clinical laboratory sciences student developed an educational algorithm to guide urinalysis dipstick interpretation, culturing necessity, and treatment decisions based on evidence-based practice. Our study considered patient records from February 1, 2022, to February 28, 2022, as retrospective (prealgorithm implementation) data and January 24, 2023, to February 22, 2023, as prospective (postalgorithm implementation) data. Data collected from the electronic medical record included deidentified patient information, urinalysis results, culture dates and outcomes, antibiotic prescriptions, urinary tract infection or asymptomatic bacteriuria diagnoses, provider details, adverse pregnancy outcomes, and demographics. Data analysis using SPSS (version 29; SPSS IBM, Armonk, NY) involved chi-square tests, likelihood ratios, and effect size calculations, with P values of <.05 considered statistically significant.

RESULTS

This study examined a total of 1176 patient records. Preimplementation data included 440 records, of which 224 were abnormal urinalyses and 216 were normal urinalyses. Postimplementation data included 736 records, of which 255 were abnormal urinalyses and 481 were normal urinalysis. The patient demographics predominantly featured White individuals (87%), with a median maternal age of 27 years and a gestational age of 32 weeks. Our preimplementation analyses revealed significant associations of algorithm deviations with both culture utilization (P<.001) and antibiotic stewardship (P<.001). However, no significant association was observed between algorithm deviations and adverse patient outcomes. Culture underutilization decreased significantly from 43.0% (189/440) before implementation to 29.5% (217/736) after implementation (P<.001). The overall reduction in asymptomatic bacteriuria prevalence from 16.3% (8/49) to 6.7% (10/67) suggests a decrease of nearly 60.0%. In addition, antibiotic overprescription decreased significantly from 1.6% (4/258) before implementation to 0.8% (4/522) after implementation (P=.003), with a reduction from 7.1% (3/42) to 2.4% (1/41) among abnormal urinalyses.

CONCLUSION

Our findings show a strong alignment between the use of the algorithm and subsequent clinical decisions, underscoring its potential to enhance patient care and management in obstetrical settings. Adherence to the algorithm was higher among providers displaying prudent antibiotic use.

Preoperative urine culture with contaminants is not associated with increased risk for urinary tract infection after ureteroscopic stone treatment

PURPOSE

We aimed to assess whether the presence of contaminants in the pre-operative urine culture (preop-UC) predicts postoperative urinary tract infection (postop-UTI) in patients undergoing elective ureteroscopy with laser lithotripsy.

METHODS

A retrospective chart review was performed from 01/2019 to 12/2021 examining patients with unilateral stone burden ≤ 2 cm who underwent ureteroscopy with laser lithotripsy and had a preop-UC within 3 months. Positive, negative, contaminated, and polymicrobial definitions for UCs were established in accordance with current guidelines. Patients with positive and polymicrobial cultures were excluded. Postop-UTI was defined as the presence of urinary symptoms and a positive UC within 30 days of the procedure. Multivariable logistic regression models were utilized to evaluate risk factors for contamination in the preop-UC and the risk of postop-UTI.

RESULTS

A total of 201 patients met the inclusion-exclusion criteria. Preop-UC was negative in 153 patients and contaminated in 48 patients. Significant contaminant-related factors included female gender and increased BMI. Postop-UTI was diagnosed in 3.2% of patients with negative preop-UCs and 4.2% of patients with contaminants, with no difference between groups (p = 0.67). The regression model determined that the presence of contaminants in preop-UC failed to predict postop-UTI (OR 0.69, p = 0.64).

CONCLUSION

The presence of contaminants in preop-UCs is not associated with an increased risk of postop-UTIs after ureteroscopy. Our study supports that contaminants in the preop-UC can be interpreted as a negative UC in terms of postop-UTI risk stratification. Preoperative antibiotics should not be prescribed for patients undergoing uncomplicated ureteroscopy for stone surgery in the setting of a contaminated preop-UC.

Urinary Tract Infections in Pregnant Individuals

SUMMARY

Urinary tract infection (UTI) is one of the more common perinatal complications, affecting approximately 8% of pregnancies (1, 2). These infections represent a spectrum, from asymptomatic bacteriuria, to symptomatic acute cystitis, to the most serious, pyelonephritis. The presence of UTIs has been associated with adverse pregnancy outcomes, including increased rates of preterm delivery and low birth weight. Screening for and treating asymptomatic bacteriuria have been shown in multiple studies to reduce the incidence of pyelonephritis in pregnancy (3-5). Given the frequency at which UTIs are encountered in pregnancy, the ability to recognize, diagnose, and treat them is essential for those providing care to pregnant individuals. This Clinical Consensus document was developed using an established protocol in conjunction with the authors listed.

Envisioning Future UTI Diagnostics

Urinary tract infections (UTIs) are among the most common bacterial infections in the United States and are a major driver of antibiotic use - both appropriate and inappropriate - across healthcare settings. UTI treatment has become complex due to antibacterial resistance; one quarter of urinary tract isolates of Escherichia coli in the United States in 2017 were resistant to fluoroquinolones and one third to trimethoprimsulfamethoxazole (1), agents with historically predictable activity against E. coli. As a result, more broad-spectrum antibiotics are being used to treat UTIs, contributing to selection of further antibiotic resistance.