A multicenter case–control study of diagnostic tests for urinary tract infection in the presence of urolithiasis

High risk and low prevalence diseases: Infected urolithiasis

INTRODUCTION

Infected urolithiasis is a serious condition that carries with it a high rate of morbidity and mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of infected urolithiasis, including presentation, diagnosis, and management in the emergency department based on current evidence.

DISCUSSION

Although urolithiasis is common and the vast majority can be treated conservatively, the presence of a concomitant urinary tract infection significantly increases the risk of morbidity, to include sepsis and mortality. Identification of infected urolithiasis can be challenging as patients may have symptoms similar to uncomplicated urolithiasis and/or pyelonephritis. However, clinicians should consider infected urolithiasis in toxic-appearing patients with fever, chills, dysuria, and costovertebral angle tenderness, especially in those with a history of recurrent urinary tract infections. Positive urine leukocyte esterase, nitrites, and pyuria in conjunction with an elevated white blood cell count may be helpful to identify infected urolithiasis. Patients should be resuscitated with fluids and broad-spectrum antibiotics. Additionally, computed tomography and early urology consultation are recommended to facilitate definitive care.

CONCLUSIONS

An understanding of infected urolithiasis can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Predicting urine culture results in candidates for lithotripsy

Background

Urological guidelines assert that "urine culture should be obtained" before surgical management of ureteral or kidney stones. Thus, many surgeries are delayed by 1-3 days until the results of urine culture are available. During this time, the patient frequently experience pain and possible kidney damage. We investigated the hypothesis that it is possible to predict the results of urine culture in candidates for surgical intervention using parameters that are accessible immediately upon admission.

Materials and methods

A database of 1000 patients who underwent either percutaneous nephrolithotomy (PCNL) or ureteroscopy/retrograde intrarenal surgery was analyzed. Eleven parameters potentially related to urinary infections and accessible to the clinician at the emergency department were correlated with the preoperative urine culture results.

Results

Of the patients, 234 (23.4 %) had positive cultures. On multivariate analysis, only sex, hydronephrosis grade, and history of previous nephrolithotomy were significantly associated with a positive preoperative urine culture. The risk of a positive culture can be easily determined from a simple table or an Excel-based calculator. This risk could be as low as 0.45% for a man without a history of PCNL and no hydronephrosis (4% in a woman with similar parameters) or as high as 79.5% in a man with a history of PCNL and hydronephrosis (85% in a woman with similar parameters).

Conclusions

The risk of preoperative positive urine culture can be predicted using 3 parameters that are accessible upon admission. In low-risk cases, prompt surgical treatment can be provided, eliminating the anticipation time for urine culture results.

Prospective Evaluation of Predictive Parameters for Urinary Tract Infection in Patients with Acute Renal Colic

BACKGROUND

Acute renal colic (ARC) is an emergency that can mostly be treated conservatively, but can be life threatening in combination with urinary tract infection (UTI). Assessment for infection includes white blood cell (WBC) count and C-reactive protein (CRP), but these parameters are often unspecifically elevated and might lead to antibiotic over-therapy. In times of increasing antibiotic resistance, however, unnecessary antibiotic therapy should be avoided.

OBJECTIVES

The goal of the study was to investigate the prevalence of UTI proven by urine culture (UC) in patients with ARC and to identify predictive factors in the emergency setting.

PATIENTS AND METHODS

We prospectively enrolled 200 consecutive patients with ARC and evaluated blood test results, urinalysis, UC, symptoms suspicious for UTI, and time between symptom onset and admission, as well as body temperature. Logistic regression analyses were performed to identify predictive factors.

RESULTS

There were 196 patients eligible for statistical analysis. UTI proven by positive UC was detected in 26 patients (13%). On multivariate logistic regression analysis, suspicious urinalysis (positive nitrite or bacteria > 20/high-power field [hpf] or WBC > 20/hpf), patient age ≥ 54 years and CRP ≥ 1.5 mg/dL (fivefold increase) were significant predictors for the presence of UTI. Neither elevated WBC count nor typical UTI symptoms were associated with UTI.

CONCLUSIONS

Based on our results, a routine antibiotic prophylaxis in patients with ARC does not seem to be appropriate. Patient age and CRP can help to decide if antibiotic treatment might be indicated, even in case of a not clearly suspicious urinalysis.