Urinalysis is not reliable to detect a urinary tract infection in febrile infants presenting to the ED

Prevalence of Enterococcal Urinary Tract Infections With Positive Nitrites in Urinalysis in Pediatric Patients With High-Risk for Enterococcal Infections

Enterococcus is a relatively uncommon pathogen that causes urinary tract infections (UTIs) in healthy children. Most enterococcal infections occur in patients with risk factors such as anatomical or functional urinary tract anomalies, also known as CAKUT (congenital anomalies of kidney and urinary tract). Children who are suspected of having UTIs and who have certain risk factors are often treated specifically for enterococcal infection as part of their empiric regimen. Our primary objective was to determine the prevalence of enterococcal UTIs among high-risk children, and specifically among those with positive nitrite tests, with the goal of avoiding treatment with specific anti-enterococcal agents. This retrospective study included all the episodes of UTI treated at a tertiary pediatric center during 2010 to 2018. The data collected from medical records included nephrological and urological risk factors, nitrite status, and isolated pathogens. Of 931 episodes of UTI, 467 (50%) were considered high-risk. In all, 24 of the latter had Enterococcus as a single pathogen; 23 (96%) of these occurred in patients with negative nitrites in the first urine dipstick taken. The sole patient with high-risk factors, a positive nitrite test and coexisting enterococcal UTI had a history of previous enterococcal UTIs. In pediatric patients with nephrological and urological risk factors, who have positive nitrites in urinalysis, the risk for enterococcal UTI appears substantially low. Therefore, in this context, specific anti-enterococcal empirical antibiotic therapy may be unnecessary.

Nitrite-negative results in urinary tract infection by Enterobacterales: does the nitrite dipstick test have low sensitivity?

Urinary tract infection (UTI) is one of the most common bacterial infections among humans. Urine culture is the gold standard diagnostic method for UTI; however, the dipstick test for nitrite is a widely used method signalling the presence of urinary nitrate-reducing bacteria. Unlike the gold standard, the dipstick test is easy to perform, while it is also less time-consuming and less expensive, and produces a result in a few minutes. This study investigates the sensitivity of the dipstick test for nitrite compared with the Griess test in urine samples from UTI caused by Enterobacterales species. We used the Griess test, which is the gold standard in nitrite measurement, to determine the sensitivity of the nitrite dipstick test. Semiquantitative urine culture was performed using standard procedures, and Enterobacterales identification was performed by manual conventional biochemical tests. In the first sample selection, 3 % (8/267) of urine samples suspected of UTI, analysed from March to April 2016, were nitrite-negative by dipstick test but positive for Enterobacterales in the urine culture. In the second sample selection, 5 % (2/44) of urine samples from October to December 2022 were also nitrite-negative but showed urine Enterobacterales isolation. All nitrite-negative dipstick results were consistent with the Griess test. Escherichia coli was the most prevalent bacterium, followed by Klebsiella pneumoniae, independent of sample selection. The dipstick test is a safe alternative for investigating nitrite in urine samples. We believe that the cause of nitrite-negative results is a lack of dietary nitrate, dilution of urine and exogenous interference (e.g. ascorbic acid). These findings support the idea that standard urine culture is necessary to rule out UTI.

Optimal Urine Culture Diagnostic Stewardship Practice- Results from an Expert Modified-Delphi Procedure

BACKGROUND

Urine cultures are nonspecific for infection and often lead to misdiagnosis of urinary tract infection and unnecessary antibiotics. Diagnostic stewardship is a set of procedures that modifies test ordering, processing, and reporting in order to optimize diagnosis and downstream treatment. This study aimed to develop expert guidance on best practices for urine culture diagnostic stewardship.

METHODS

A RAND-modified Delphi approach with a multidisciplinary expert panel was used to ascertain diagnostic stewardship best practices. Clinical questions to guide recommendations were grouped in three thematic areas (ordering, processing, reporting) in practice settings of emergency department, inpatient, ambulatory, and long-term care. Fifteen experts ranked recommendations on a 9-point Likert scale. Recommendations on which the panel did not reach agreement were discussed in a virtual meeting, and a then second round of ranking by email was completed. After secondary review of results and panel discussion, a series of guidance statements was developed.

RESULTS

165 questions were reviewed with the panel reaching agreement on 104, leading to 18 overarching guidance statements. The following strategies were recommended to optimize ordering urine cultures: requiring documentation of symptoms, alerts to discourage ordering in the absence of symptoms, and cancelling repeat cultures. For urine culture processing, conditional reflex urine cultures and urine white blood cell as criteria were supported. For urine culture reporting, appropriate practices included nudges to discourage treatment under specific conditions and selective reporting of antibiotics to guide therapy decisions.

CONCLUSIONS

These 18 guidance statements can optimize use of the imperfect urine culture for better patient outcomes.

Diagnostic value of biomarkers for paediatric urinary tract infections in primary care: systematic review and meta-analysis

Background

Accurate diagnosis of urinary tract infection is essential as children left untreated may suffer permanent renal injury.

Aim

To compare the diagnostic values of biomarkers or clinical prediction rules for urinary tract infections in children presenting to ambulatory care.

Design and setting

Systematic review and meta-analysis of ambulatory care studies.

Methods

Medline, Embase, WOS, CINAHL, Cochrane library, HTA and DARE were searched until 21 May 2021. We included diagnostic studies on urine or blood biomarkers for cystitis or pyelonephritis in children below 18 years of age. We calculated sensitivity, specificity and likelihood ratios. Data were pooled using a bivariate random effects model and a Hierarchical Summary Receiver Operating Characteristic analysis.

Results

Seventy-five moderate to high quality studies were included in this review and 54 articles in the meta-analyses. The area under the receiver-operating-characteristics curve to diagnose cystitis was 0.75 (95%CI 0.62 to 0.83, n = 9) for C-reactive protein, 0.71 (95% CI 0.62 to 0.80, n = 4) for procalcitonin, 0.93 (95% CI 0.91 to 0.96, n = 22) for the dipstick test (nitrite or leukocyte esterase ≥trace), 0.94 (95% CI 0.58 to 0.98, n = 9) for urine white blood cells and 0.98 (95% CI 0.92 to 0.99, n = 12) for Gram-stained bacteria. For pyelonephritis, C-reactive protein < 20 mg/l had LR- of 0.10 (95%CI 0.04–0.30) to 0.22 (95%CI 0.09–0.54) in children with signs suggestive of urinary tract infection.

Conclusions

Clinical prediction rules including the dipstick test biomarkers can support family physicians while awaiting urine culture results. CRP and PCT have low accuracy for cystitis, but might be useful for pyelonephritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-021-01530-9.

Diagnosis and Management of UTI in Febrile Infants Age 0-2 Months: Applicability of the AAP Guideline

Urinary tract infections (UTIs) are the most common bacterial infection in young infants. The American Academy of Pediatrics' (AAP) clinical practice guideline for UTIs focuses on febrile children age 2-24 months, with no guideline for infants <2 months of age, an age group commonly encountered by pediatric hospitalists. In this review, we assess the applicability of the AAP UTI Guideline's action statements for previously healthy, febrile infants <2 months of age. We also discuss additional considerations in this age group, including concurrent bacteremia and routine testing for meningitis.

Evaluation of BacterioScan 216Dx in Comparison to Urinalysis as a Screening Tool for Diagnosis of Urinary Tract Infections in Children

Urinalysis (UA) has routinely been used as a screening tool prior to urine culture set up. BacterioScan 216Dx is an FDA-cleared semiautomated system to detect bacterial growth in urine. The aim of this study was to evaluate 216Dx in comparison to UA for diagnosis of urinary tract infection (UTI) in children. Clean-catch, unpreserved urine samples from children aged <18 years were tested by 216Dx, and positive urine samples in media were processed for direct bacterial identification by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Sensitivity and specificity of 216Dx and urinalysis (UA) were determined against urine culture. Of 287 urine samples obtained from children (median age, 108 months), 44.0% and 56.0% were UA positive and negative, respectively, while 216Dx detected 27% and 73% as positive and negative, respectively. Compared to culture, the overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 216Dx versus UA were 92.1% versus 97.3%, 82.7% versus 63.8%, 44.8% versus 29.1%, and 98.6% versus 99.3%, respectively. Among 216Dx true-positive (TP) samples (n = 35), 77.0% were successfully identified directly from broth by MALDI-TOF. Among urine samples that were identified as contaminated by culture (n = 127; 44%), the 216Dx detected 93 (73.0%) as negative while UA detected 69 (54.0%) as negative. Although the sensitivities of 216Dx and UA are comparable, the specificity of 216Dx was higher than that of UA. The 216Dx can be used as an alternative/adjunct screening tool to UA to rule out urinary tract infection (UTI) in children. Compared to culture, the faster turnaround time (3 hours) of 216Dx has the potential to reduce unnecessary antibiotic use and improve patient management.

Urinary Tract Infection in Children

BACKGROUND

Urinary Tract Infection (UTI) is a common infection in children. Prompt diagnosis and appropriate treatment are very important to reduce the morbidity associated with this condition.

OBJECTIVE

To provide an update on the evaluation, diagnosis, and treatment of urinary tract infection in children.

METHODS

A PubMed search was completed in clinical queries using the key terms "urinary tract infection", "pyelonephritis" OR "cystitis". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature and the pediatric age group. Patents were searched using the key terms "urinary tract infection" "pyelonephritis" OR "cystitis" from www.google.com/patents, http://espacenet.com, and www.freepatentsonline.com.

RESULTS

Escherichia coli accounts for 80 to 90% of UTI in children. The symptoms and signs are nonspecific throughout infancy. Unexplained fever is the most common symptom of UTI during the first two years of life. After the second year of life, symptoms and signs of pyelonephritis include fever, chills, rigor, flank pain, and costovertebral angle tenderness. Lower tract symptoms and signs include suprapubic pain, dysuria, urinary frequency, urgency, cloudy urine, malodorous urine, and suprapubic tenderness. A urinalysis and urine culture should be performed when UTI is suspected. In the work-up of children with UTI, physicians must judiciously utilize imaging studies to minimize exposure of children to radiation. While waiting for the culture results, prompt antibiotic therapy is indicated for symptomatic UTI based on clinical findings and positive urinalysis to eradicate the infection and improve clinical outcome. The choice of antibiotics should take into consideration local data on antibiotic resistance patterns. Recent patents related to the management of UTI are discussed.

CONCLUSION

Currently, a second or third generation cephalosporin and amoxicillin-clavulanate are drugs of choice in the treatment of acute uncomplicated UTI. Parenteral antibiotic therapy is recommended for infants ≤ 2 months and any child who is toxic-looking, hemodynamically unstable, immunocompromised, unable to tolerate oral medication, or not responding to oral medication. A combination of intravenous ampicillin and intravenous/intramuscular gentamycin or a third-generation cephalosporin can be used in those situations. Routine antimicrobial prophylaxis is rarely justified, but continuous antimicrobial prophylaxis should be considered for children with frequent febrile UTI.

Accuracy of the Urinalysis for Urinary Tract Infections in Febrile Infants 60 Days and Younger

OBJECTIVES

Reports of the test accuracy of the urinalysis for diagnosing urinary tract infections (UTIs) in young febrile infants have been variable. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, in young febrile infants.

METHODS

We performed a planned secondary analysis of data from a prospective study of febrile infants ≤60 days old at 26 emergency departments in the Pediatric Emergency Care Applied Research Network. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, by using 2 definitions of UTI: growth of ≥50 000 or ≥10 000 colony-forming units (CFUs) per mL of a uropathogen. We defined a positive urinalysis by the presence of any leukocyte esterase, nitrite, or pyuria (>5 white blood cells per high-power field).

RESULTS

Of 4147 infants analyzed, 289 (7.0%) had UTIs with colony counts ≥50 000 CFUs/mL, including 27 (9.3%) with bacteremia. For these UTIs, a positive urinalysis exhibited sensitivities of 0.94 (95% confidence interval [CI]: 0.91-0.97), regardless of bacteremia; 1.00 (95% CI: 0.87-1.00) with bacteremia; and 0.94 (95% CI: 0.90-0.96) without bacteremia. Specificity was 0.91 (95% CI: 0.90-0.91) in all groups. For UTIs with colony counts ≥10 000 CFUs/mL, the sensitivity of the urinalysis was 0.87 (95% CI: 0.83-0.90), and specificity was 0.91 (95% CI: 0.90-0.92).

CONCLUSIONS

The urinalysis is highly sensitive and specific for diagnosing UTIs, especially with ≥50 000 CFUs/mL, in febrile infants ≤60 days old, and particularly for UTIs with associated bacteremia.

Neutrophil Gelatinase-Associated Lipocalin: A Biomarker for Early Diagnosis of Urinary Tract Infections in Infants

Early diagnosis of urinary tract infection (UTI) is challenging in infants due to unspecific symptoms, difficulty in urine collection and possible contamination. The aim of this study was to assesses the usefulness of serum and urine neutrophil gelatinase-associated lipocalin (sNGAL and uNGAL, respectively) in the diagnosis of febrile and non-febrile UTI in infants. This prospective observational study enrolled 66 infants with the first episode of UTI and 18 healthy controls. At the time of enrollment, sNGAL, uNGAL, urinalysis, urine culture, white blood cell count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), and serum creatinine (sCr) were assessed. We found that, on average, both sNGAL and uNGAL levels were significantly higher in febrile UTI, compared to non-febrile UTI and controls. In turn, the mean sNGAL level, but not uNGAL, was significantly higher in the non-febrile UTI group compared to controls. sNGAL positively correlated with WBC, CRP, ESR and PCT, and uNGAL with CRP and leukocyturia. The receiver operating curves (ROC) demonstrate that the optimum cut-off of 76.2 ng/ml for sNGAL (sensitivity 92.9%, specificity 94.4%, and the area under the curve (AUC) of 0.98) and of 42.2 ng/ml for uNGAL (sensitivity 73.8%, specificity 72.2%, and AUC of 0.76) for diagnosing febrile UTI and 39.0 ng/ml for sNGAL (sensitivity 83.3%, specificity 55.6%, and AUC of 0.70) for diagnosing non-febrile UTI. In conclusion, serum NGAL is an excellent marker for the early diagnosis of febrile UTI, with sensitivity and specificity higher than those of urine NGAL. Diagnostic sensitivity of serum NGAL is smaller in non-febrile infants suffering from UTI, and urine NGAL is not useful for this purpose at all.

Point-Counterpoint: Reflex Cultures Reduce Laboratory Workload and Improve Antimicrobial Stewardship in Patients Suspected of Having Urinary Tract Infections

Urinary tract infections (UTIs) are frequent and lead to a large number of clinical encounters. A common management strategy for patients suspected of having a urinary tract infection is to test for pyuria and bacteria by urine analysis (UA) of midstream urine, with initiation of antibiotic therapy and urine culture if one or both tests are positive. Although this practice was first used in an outpatient setting with midstream urine samples, some institutions allow its use in the management of catheterized patients. The ideas behind the reflex urine culture are to limit laboratory workload by not performing culture on negative specimens and to improve antimicrobial stewardship by not giving antimicrobials to patients with negative UA results. The questions are, first, whether reflex urine culture reduces workloads significantly and, second, whether it improves antimicrobial stewardship in the era of increasing numbers of urinary tract infections due to extensively drug-resistant Gram-negative bacilli. Romney Humphries from UCLA supports the idea that reflex urine cultures are of value and describes what reflex parameters are most useful, while Jennifer Dien Bard of Children's Hospital Los Angeles discusses their limitations.

Can a simple urinalysis predict the causative agent and the antibiotic sensitivities?

OBJECTIVES

The objective of this study was (1) to determine the reliability of urinalysis (UA) for predicting urinary tract infection (UTI) in febrile children, (2) to determine whether UA findings can predict Escherichia coli versus non-E. coli urinary tract infection, and (3) to determine if empiric antibiotics should be selected based on E. coli versus non-E. coli infection predictions.

METHODS

This was a retrospective chart review of children from 2 months to 2 years of age who presented to the emergency department with fever (rectal temperature >100.4°F) and had a positive urine culture. This study was conducted between January 2004 and December 2007. Negative UA was defined as urine white blood cell count less than 5 per high-power field, negative leukocyte esterase, and negative nitrites. Urine cultures were classified into E. coli and non-E. coli groups. These groups were compared for sex, race, and UA findings. Multivariate forward logistic regression, using the Wald test, was performed to calculate the likelihood ratio (LR) of each variable (eg, sex, race, UA parameters) in predicting UTI. In addition, antibiotic sensitivities between both groups were compared.

RESULTS

Of 749 medical records reviewed, 608 were included; negative UA(-) was present in 183 cases, and positive UA(+) was observed in 425 cases. Furthermore, 424 cases were caused by E. coli, and 184 were due to non-E. coli organisms. Among 425 UA(+) cases, E. coli was identified in 349 (82.1%), whereas non-E. coli organisms were present in 76 (17.9%); in contrast, in 183 UA(-) cases, 108 (59%) were due to non-E. coli organisms versus 75 (41%), which were caused by E. coli. Urinalysis results were shown to be associated with organism group (P < 0.001). Positive leukocytes esterase had an LR of 2.5 (95% confidence interval [CI], 1.5-4.2), positive nitrites had an LR of 2.8 (95% CI, 1.4-5.5), and urine white blood cell count had an LR of 1.8 (95% CI, 1.3-2.4) in predicting E. coli versus non-E. coli infections. Antibiotic sensitivity compared between UA groups demonstrated equivalent superiority of cefazolin (94.7% sensitive in UA(+) vs 84.0% in UA(-) group; P < 0.0001), cefuroxime (98.2% vs 91.7%; P < 0.001), and nitrofurantoin (96.1% vs 82.2%; P < 0.0001) in the UA(+) group. In contrast, the UA(-) group showed significant sensitivity to trimethoprim-sulfamethoxazole (82.2% vs 71.3% in UA(+); P = 0.008).

CONCLUSIONS

Urinalysis is not an accurate predictor of UTI. A positive urine culture in the presence of negative UA most likely grew non-E. coli organisms, whereas most UA(+) results were associated with E. coli. This study also highlighted local patterns of antibiotic resistance between E. coli and non-E. coli groups. Negative UA results in the presence of strong suspicion of a UTI suggest a non-E. coli organism, which may be best treated with trimethoprim-sulfamethoxazole. Conversely, UA(+) results suggest E. coli, which calls for treatment with cefazolin or cefuroxime.