Pyuria and Urine Concentration for Identifying Urinary Tract Infection in Young Children.

OBJECTIVES: Accuracy of pyuria for urinary tract infection (UTI) varies with urine concentration. Our objective of this study was to determine the optimal white blood cell (WBC) cutoff for UTI in young children at different urine concentrations as measured by urine specific gravity. METHODS: Retrospective cross-sectional study of children <24 months of age evaluated in the emergency department for suspected UTI with paired urinalysis and urine culture during a 6-year period. The primary outcome was positive urine culture result as described in the American Academy of Pediatrics clinical practice guideline culture thresholds. Test characteristics for microscopic pyuria cut points and positive leukocyte esterase (LE) were calculated across 3 urine specific gravity groups: low <1.011, moderate 1.011 to 1.020, and high >1.020. RESULTS: Of the total 24 171 patients analyzed, urine culture result was positive in 2003 (8.3%). Urine was obtained by transurethral in-and-out catheterization in 97.9%. Optimal WBC cutoffs per high-power field (HPF) were 3 (positive likelihood ratio [LR+] 10.5; negative likelihood ratio [LR-] 0.12) at low, 6 (LR+ 12; LR- 0.14) at moderate, and 8 (LR+ 11.1; LR- 0.35) at high urine concentrations. Likelihood ratios for small positive LE from low to high urine concentrations (LR+ 25.2, LR- 0.12; LR+ 33.1, LR- 0.15; LR+ 37.6, LR- 0.41) remained excellent. CONCLUSIONS: Optimal pyuria cut point in predicting positive urine culture results changes with urine concentration in young children. Pyuria thresholds of 3 WBCs per HPF at low urine concentrations whereas 8 WBCs per HPF at high urine concentrations have optimal predictive value for UTI. Positive LE is a strong predictor of UTI regardless of urine concentration.

Urine Concentration and Pyuria for Identifying UTI in Infants.

BACKGROUND: Varying urine white blood cell (WBC) thresholds have been recommended for the presumptive diagnosis of urinary tract infection (UTI) among young infants. These thresholds have not been studied with newer automated urinalysis systems that analyze uncentrifuged urine that might be influenced by urine concentration. Our objective was to determine the optimal urine WBC threshold for UTI in young infants by using an automated urinalysis system, stratified by urine concentration. METHODS: Retrospective cross-sectional study of infants aged <3 months evaluated for UTI in the emergency department with paired urinalysis and urine culture. UTI was defined as ≥50 000 colony-forming units/mL from catheterized specimens. Test characteristics were calculated across a range of WBC and leukocyte esterase (LE) cut-points, dichotomized into specific gravity groups (dilute <1.015; concentrated ≥1.015). RESULTS: Twenty-seven thousand infants with a median age of 1.7 months were studied. UTI prevalence was 7.8%. Optimal WBC cut-points were 3 WBC/high-power field (HPF) in dilute urine (likelihood ratio positive [LR+] 9.9, likelihood ratio negative [LR‒] 0.15) and 6 WBC/HPF (LR+ 10.1, LR‒ 0.17) in concentrated urine. For dipstick analysis, positive LE has excellent test characteristics regardless of urine concentration (LR+ 22.1, LR‒ 0.12 in dilute urine; LR+ 31.6, LR‒ 0.22 in concentrated urine). CONCLUSIONS: Urine concentration should be incorporated into the interpretation of automated microscopic urinalysis in young infants. Pyuria thresholds of 3 WBC/HPF in dilute urine and 6 WBC/HPF in concentrated urine are recommended for the presumptive diagnosis of UTI. Without correction of specific gravity, positive LE by automated dipstick is a reliably strong indicator of UTI.

Acute focal bacterial nephritis in 25 children.

Acute focal bacterial nephritis (AFBN), formerly known as lobar nephronia, is a rare form of interstitial bacterial nephritis. Most often described in adults with diabetes, there is only limited knowledge of AFBN in children. Ultrasound shows circular hypoechogenic, hypoperfused parenchyma lesions, which may be misdiagnosed as a renal abscess or tumor. From 1984 to 2005, AFBN was diagnosed in 30 children at the University Hospital Münster and the General Hospital Celle, Germany. Data of 25 cases (14 girls, 11 boys) were available for retrospective evaluation. Twenty-five children with AFBN, mean age 4.5 years (range: 0.25-17.5 years), were followed up on average 4.2 years (range: 0.5-11 years). All children were admitted to hospital due to fever and rapid deterioration of clinical condition, initially suspected of having meningitis (four patients), urinary tract infections (five patients), renal tumor (three patients), pneumonia (two patients), appendicitis (one patient), or with only unspecific symptoms (ten patients). AFBN was diagnosed by ultrasound on average 3 days (range: 1-10 days) after onset of symptoms. Pyuria was found in 18/25 children, bacteriuria in 20/25 children, and hematuria in one patient. Blood cultures were negative in all but one patient. Urinary tract abnormalities were found in 12 children, including vesicoureteral reflux (8), megaureter (1), urethral valves (1), unilateral renal hypoplasia (1), and one patient with megacystis, megaureter, caudal dystopic left kidney combined with hypoplasia and dysplasia of the right kidney. High-resolution ultrasound showed AFBN lesions to have resolved completely within 12 weeks after onset of intravenous antibiotic therapy in 20/25 children. Renal parenchymal cysts remained in three cases and focal scarring in two. Blood pressure and renal function was normal in 24/25 cases. AFBN should be suspected in children with fever and rapid deterioration of clinical condition. Residual lesions such as cysts or scarring of renal parenchyma could remain.

Pyocystis: two case reports of patients in renal failure.

Two cases of pyocystis in patients in end-stage renal disease are reported. Pyocystis is a recognized complication of urinary diversion procedures, but also occurs in anuric or oliguric hemodialysis patients. The treatment differs from ordinary cystitis, requiring catheterization, bladder irrigation, and intravesical antibiotic instillation. When undiagnosed, pyocystis may progress to sepsis and death.

New support for a folk remedy: cranberry juice reduces bacteriuria and pyuria in elderly women.

Cranberry juice has developed a following as a simple, nonpharmacologic means to reduce or treat urinary tract infections, yet the scientific basis for such a claim has been lacking. A new study suggests that bacterial infections (bacteriuria) and associated influx of white blood cells into the urine (pyuria) can be reduced by nearly 50% in elderly women who drink 300 mL of cranberry juice cocktail each day over the course of a 6-month study. The results of this study suggest that consumption of cranberry juice is more effective in treating than preventing bacteriuria and pyuria. Along with earlier reports on the ability of cranberry juice to inhibit bacterial adherence to urinary epithelial cells in cell culture, this new work suggests that drinking cranberry juice each day may be clinically useful. Additional work must be conducted, however, to more completely define the efficacy of cranberry juice.