Uriscreen, a rapid enzymatic urine screening test: useful predictor of significant bacteriuria in pregnancy

Paper and thread as media for the frugal detection of urinary tract infections (UTIs)

Urinary tract infections (UTIs) make up a significant proportion of the global burden of disease in vulnerable groups and tend to substantially impair the quality of life of those affected, making timely detection of UTIs a priority for public health. However, economic and societal barriers drastically reduce accessibility of traditional lab-based testing methods for critical patient groups in low-resource areas, negatively affecting their overall healthcare outcomes. As a result, cellulose-based materials such as paper and thread have garnered significant interest among researchers as substrates for so-called frugal analytical devices which leverage the material's portability and adaptability for facile and reproducible diagnoses of UTIs. Although the field may be only in its infancy, strategies aimed at commercial penetration can appreciably increase access to more healthcare options for at-risk people. In this review, we catalogue recent advances in devices that use cellulose-based materials as the primary housing or medium for UTI detection and chart out trends in the field. We also explore different modalities employed for detection, with particular emphasis on their ability to be ported onto discreet casings such as sanitary products.

The Uriscreen Test to Detect Significant A symptomatic Bacteriuria During Pregnancy

BACKGROUND

Asymptomatic bacteriuria (ASB) occurs in 2-11% of pregnancies and it is a clear predisposition to the development of acute pyelonephritis, which, in turn, poses risk to mother and fetus. Treatment of bacteriuria during pregnancy reduces the incidence of pyelonephritis. Therefore, it is recommended to screen for ASB at the first prenatal visit. The gold standard for detection of bacteriuria during pregnancy is urine culture, but this test is expensive, time-consuming, and labor-intensive.

OBJECTIVE

To determine the reliability of an enzymatic urine screening test (Uriscreen; Savyon Diagnostics, Ashdod, Israel) for detecting ASB in pregnancy.

METHODS

Catheterized urine samples were collected from 150 women who had routine prenatal screening for ASB. Patients with urinary symptoms, active vaginal bleeding, or who were previously on antibiotics therapy were excluded from the study. Sensitivity, specificity, and the positive and negative predictive values for the Uriscreen were estimated using urine culture as the criterion standard. Urine cultures were considered positive if they grew >10(5) colony-forming units of a single uropathogen.

RESULTS

Twenty-eight women (18.7%) had urine culture results indicating significant bacteriuria, and 17 of these 28 specimens had positive enzyme activity. Of 122 samples with no growth, 109 had negative enzyme activity. Sensitivity, specificity, and positive and negative predictive values for the Uriscreen test were 60.7% (+/-18.1), 89.3% (+/-5.6), 56.6%, and 90.8%, respectively.

CONCLUSION

The Uriscreen test had inadequate sensitivity for rapid screening of bacteriuria in pregnancy.

Asymptomatic group B streptococcal bacteriuria among pregnant women in Saudi Arabia

This study aims to determine the asymptomatic bacteriuria in pregnancy due to GBS and its antimicrobial sensitivity pattern for planning strategy for the management of these cases and also to determine the relationship between asymptomatic bacteriuria and pyuria. A total of 3863 consecutive urine specimens were collected from 3863 pregnant women with asymptomatic bacteriuria attending the obstetrics and gynaecology department of our hospital over a period of two years. Specimens were processed using standard microbiological procedures. All the subjects were evaluated for bacteriuria. The prevalence of asymptomatic bacteriuria due to group B streptococci (GBS) was 82/3863 (2.1%) among pregnant women in Saudi Arabia. Among these, 69/82 patients (84.2%) had clinical and microbiological features consistent with cystitis, versus 13/82 (15.8%) for pyelonephritis. About 51.2% (42/82) of the patients who had urine analysis performed had positive results based on positive urinary leucocyte esterase and pyuria. Disc-diffusion analysis of all 82 GBS isolates showed that they were highly susceptible to Augmentin and linezolid. Screening for bacteriuria in pregnancy and proper treatment must be considered as an essential part of antenatal care in this community. To prevent asymptomatic bacteriuria complications, all pregnant women should be screened at the first antenatal visit. A negative test for pyuria is not a reliable indicator of the absence of asymptomatic bacteriuria in pregnant women. Further, ongoing surveillance and evaluation of outcomes in pregnancies complicated by GBS bacteriuria is required to optimise maternal and newborn care.

[Urinary tract infection in pregnancy]

Urinary tract infections, asymptomatic bacteriuria (AB), acute cystitis (AC) and acute pyelonephritis (AP), are favored by the morphological and functional changes involved in pregnancy. AB increases the risk of preterm labor, low birth weight and AP. AB should be detected by uroculture (other methods are not sufficiently effective) and treated early. Approximately 80% of cases are caused by Escherichia coli. The risks and effectiveness of the distinct antibiotic regimens should be evaluated: fosfomycin trometamol in monotherapy or as short course therapy is safe and effective for the treatment of AB and AC. AP is the most frequent cause of hospital admission for medical reasons in pregnant women and can lead to complications in 10% of cases, putting the lives of the mother and fetus at risk. Currently outpatient treatment of AP is recommended in selected cases. Adequate follow-up of pregnant women with urinary tract infections is required due to frequent recurrence.

The use of urinary dipstick tests to exclude urinary tract infection: a systematic review of the literature

Several systematic reviews have examined the use of dipstick tests to diagnose or rule in urinary tract infection (UTI). We examined the evidence relating to the use of urine leukocyte esterase and nitrite tests in adults to exclude or rule out UTI. A search of the literature from 1966 to 2003 revealed 30 studies as containing relevant and suitable information and 23 of these, which used a cut-off of 108 colony-forming units per liter, were combined in a meta-analysis. The leukocyte esterase or nitrite test combination, with one or the other test positive, was used in 14 studies, showed the highest sensitivity and the lowest negative likelihood ratio. While there was significant heterogeneity between the studies, 7 of 14 demonstrated significant decreases in pretest to posttest probability with a pooled posttest probability of 5% for the negative result. In certain circumstances, there is evidence for the use of urinalysis as a rule-out test for UTI.

Screening for Asymptomatic Bacteriuria in Pregnancy

OBJECTIVE

To compare the following 4 screening strategies for detecting asymptomatic bacteriuria (ABU) in pregnancy: urine testing with leukocyte-esterase-nitrite (LEN) strips at each prenatal visit followed by a urine culture if positive; a single urine culture at fewer than 20 weeks' gestation; 2 urine cultures, at fewer than 20 weeks' gestation and at 28 weeks' gestation; or 3 urine cultures, at fewer than 20 weeks', at 28 weeks', and at 36 weeks' gestation.

METHODS

Participants were pregnant women presenting to 2 obstetricians and 6 family physicians at outpatient family medicine and obstetrical clinics in a large Canadian urban teaching hospital. LEN dipstick urine testing was conducted at each prenatal visit. A midstream urine culture was obtained from all women before 20 weeks' gestation and at 28 weeks' and 36 weeks' gestation, as well as for positive LEN tests. Any positive urine culture in an asymptomatic woman was designated a case of ABU. The total number of ABU cases that would be detected by each of the 4 strategies (LEN dipstick testing only, a single urine culture, 2 cultures, and 3 cultures) was determined and compared.

RESULTS

There were 49 cases of ABU among 1050 women (4.7%). LEN testing at each prenatal visit identified 7 cases (14.3%), compared with 20 cases (40.8%) with 1 urine culture, 31 (63.3%) with 2 urine cultures, and 43 (87.8%) with 3 urine cultures.

CONCLUSION

A single urine culture before 20 weeks' gestation missed more than one-half the ABU cases. A culture in each trimester identified most ABU cases.

The urine dipstick test useful to rule out infections. A meta-analysis of the accuracy

BACKGROUND

Many studies have evaluated the accuracy of dipstick tests as rapid detectors of bacteriuria and urinary tract infections (UTI). The lack of an adequate explanation for the heterogeneity of the dipstick accuracy stimulates an ongoing debate. The objective of the present meta-analysis was to summarise the available evidence on the diagnostic accuracy of the urine dipstick test, taking into account various pre-defined potential sources of heterogeneity.

METHODS

Literature from 1990 through 1999 was searched in Medline and Embase, and by reference tracking. Selected publications should be concerned with the diagnosis of bacteriuria or urinary tract infections, investigate the use of dipstick tests for nitrites and/or leukocyte esterase, and present empirical data. A checklist was used to assess methodological quality.

RESULTS

70 publications were included. Accuracy of nitrites was high in pregnant women (Diagnostic Odds Ratio = 165) and elderly people (DOR = 108). Positive predictive values were >/=80% in elderly and in family medicine. Accuracy of leukocyte-esterase was high in studies in urology patients (DOR = 276). Sensitivities were highest in family medicine (86%). Negative predictive values were high in both tests in all patient groups and settings, except for in family medicine. The combination of both test results showed an important increase in sensitivity. Accuracy was high in studies in urology patients (DOR = 52), in children (DOR = 46), and if clinical information was present (DOR = 28). Sensitivity was highest in studies carried out in family medicine (90%). Predictive values of combinations of positive test results were low in all other situations.

CONCLUSIONS

Overall, this review demonstrates that the urine dipstick test alone seems to be useful in all populations to exclude the presence of infection if the results of both nitrites and leukocyte-esterase are negative. Sensitivities of the combination of both tests vary between 68 and 88% in different patient groups, but positive test results have to be confirmed. Although the combination of positive test results is very sensitive in family practice, the usefulness of the dipstick test alone to rule in infection remains doubtful, even with high pre-test probabilities.

A European perspective on nosocomial urinary tract infections I. Report on the microbiology workload, etiology and antimicrobial susceptibility (ESGNI-003 study). European Study Group on Nosocomial Infections

OBJECTIVES

To obtain information on the microbiology workload, etiology and antimicrobial susceptibility of urinary tract infection (UTI) pathogens isolated in European hospitals.

MATERIALS AND METHODS

We collected data available in the microbiology units of a large sample of European hospitals regarding the laboratory workload, diagnostic criteria, and etiology and antimicrobial resistance of the urinary isolates collected on one day (the study day).

RESULTS

Data were received from a total of 228 hospitals from 29 European countries. The average rate of urine samples cultured per 1000 admissions in 1999 was 324. The criteria to consider a positive urine culture as significant were quite variable; > or =10(4) colony-forming units (CFU)/mL for bacteria or > or =10(3) CFU/mL in the case of yeasts were the most used cut-off points. On the study day, a total of 607 micro-organisms from 522 patients with nosocomial UTI were isolated. The six most commonly isolated micro-organisms were, in decreasing order: Escherichia coli (35.6%), Enterococci (15.8%), Candida (9.4%), Klebsiella (8.3%), Proteus (7.9%) and Pseudomonas aeruginosa (6.9%). Pseudomonas was isolated more frequently in non-EU countries. The study data reveal high rates of antimicrobial resistance in UTI pathogens, especially in non-EU countries, where Pseudomonas aeruginosa presented rates of aminoglycoside resistance as high as 72% to gentamicin, 69.2% to tobramycin and 40% to amikacin.

CONCLUSIONS

Nosocomial UTI accounts for an important proportion of the workload in microbiology laboratories. A consensus on the practice and interpretation of urine cultures in Europe is needed. The levels and patterns of resistance of UTI pathogens must be a serious cause for concern and a clear reason for stricter guidelines and regulations in antimicrobial policy.

Urinary tract infections in pregnancy

Although pregnancy does not increase the prevalence of ASB in women, it does enhance the progression rate from asymptomatic to symptomatic disease. Furthermore, ASB is associated with preterm delivery. Given the fact that identification and eradication of ASB in pregnant women can lower the likelihood of pyelonephritis and prevent preterm delivery, every gravida should be systematically screened for ASB and appropriately treated. In the authors' opinion, a first-trimester urine culture remains the screening test of choice; reliance on symptoms to prompt screening is inadequate because the state of pregnancy can provoke frequency and nocturia. Multiple antibiotic regimens for ASB are safe during pregnancy and effective.

Urinary tract infection during pregnancy: a risk factor for cerebral palsy?

OBJECTIVE

To assess a possible association of urinary tract infection (UTI) during pregnancy and cerebral palsy in offspring.

DESIGN

Secondary analysis of a case-control study using structured telephone interviews and birth certificate reviews.

SETTING

Cases from community-based agencies providing services to preschool children who were developmentally delayed.

PARTICIPANTS

One hundred twelve preschool children with cerebral palsy and 153 children without cerebral palsy.

MAIN OUTCOME MEASURES

Risk for cerebral palsy.

RESULTS

The prevalence of UTI among case mothers was 17.9% compared with 5.2% among control mothers. The crude odds ratio for risk of cerebral palsy for a mother with a UTI was 3.9, whereas the adjusted odds ratio was approximately 5, indicating that the risk of having a child with cerebral palsy was 4 to 5 times greater for mothers who had a UTI during pregnancy.

CONCLUSIONS

Urinary tract infection during pregnancy was found to be a risk factor for development of cerebral palsy in offspring. Assessment for UTI should occur at the initial prenatal visit and more frequently for women with symptoms or who are at risk. Pregnant women should be educated about preventive measures for UTI. Future research is needed to assess more directly the relationship between UTI during pregnancy and cerebral palsy in offspring.

Urinary tract infections complicating pregnancy

Urinary tract infections (asymptomatic bacteriuria, cystitis, and pyelonephritis) are frequently encountered medical complications of pregnancy. The majority of infections in pregnancy are asymptomatic; however, even covert bacteriuria places the mother at risk for low birth weight and preterm birth. Pyelonephritis can result in significant maternal and fetal morbidity and mortality. Therefore, all pregnant women should be screened for asymptomatic bacteriuria, and urinary tract infections should be promptly treated to prevent adverse pregnancy outcome. This article reviews the diagnosis, etiology, treatment, and complications associated with urinary tract infections in pregnancy.