Analysis of the incidence and risk factors of fever-related ureteral stent-associated urinary tract infection in pediatric patients: a retrospective study

Introduction

Healthcare-associated infections (HAIs) are a significant issue in clinical practice, posing challenges to medical care and patient safety. Among HAIs, urinary tract infections (UTIs) are one of the most common complications, particularly in patients with indwelling medical devices such as ureteral stents. In pediatric patients, the risk of UTIs is further heightened due to anatomical and physiological differences, making it crucial to understand the incidence and risk factors of stent-associated infections (1). The advancement of modern medical technology and the widespread use of implanted materials have increased the risk of HAI (2). Ureteral stents are commonly used in pediatric urology, particularly for the treatment of conditions such as hydronephrosis, ureteral stones, and reflux nephropathy. They facilitate urinary drainage, reduce urinary obstruction, and promote postoperative recovery (3,4). However, while ureteral stenting is effective, it also carries potential complications, the most common of which is urinary tract infection (UTI) (5,6). Among these, fever-related ureteral stent-associated urinary tract infection (FUSAUTI) is one of the more serious complications, often presenting with symptoms such as fever, lumbar pain, frequency, and urgency of urination; in severe cases, it can lead to bacteremia and sepsis (7).

Currently, there is relatively limited research on the incidence, risk factors, and pathogen spectrum of FUSAUTI following pediatric urological surgery. Understanding these factors is crucial for optimizing postoperative management and reducing infection rates. This study retrospectively analyzed the data of 355 pediatric patients who underwent ureteral stent placement at Anhui Provincial Children’s Hospital from January 2018 to January 2023, aiming to assess the incidence of FUSAUTI and explore its related factors, thereby providing a basis for clinical prevention and treatment. We present this article in accordance with the STROBE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-538/rc).

Methods

General information

This study is a single-center, retrospective analysis that collected clinical data from 355 pediatric patients who underwent ureteral stent placement at Anhui Provincial Children’s Hospital between January 2018 and January 2023. All patients received surgical treatment for urological-related diseases and had ureteral stents placed postoperatively. The clinical data were sourced from the electronic medical record system of Anhui Provincial Children’s Hospital and included patients’ demographic information (age, gender), type of surgery, UTIs, duration of ureteral stent placement, postoperative fever status, and urine and blood culture results.

The American Society of Anesthesiologists (ASA) physical status classification system was used to assess the overall health status and disease severity of each patient. All ureteral stents were placed using a standardized cystoscopic retrograde technique under fluoroscopic guidance. The procedures were performed by pediatric urology surgeons with at least 5 years of experience, ensuring consistency in surgical technique. All patients received the same type of double-J stent to minimize variability in stent-related complications. All patients received standardized antibiotic prophylaxis according to institutional protocols. Prior to stent placement, all patients received a single dose of intravenous antibiotic prophylaxis within 60 minutes before the procedure. Postoperative antibiotic prophylaxis was not routinely given unless clinically indicated, such as in cases of prolonged stent placement or a history of recurrent UTIs.

This study was approved by the Ethics Committee of Anhui Provincial Children’s Hospital (No. EYLL-2023-06-009). All participants’ legal guardians provided written informed consent. All research involving humans (individuals, samples, or data) was conducted according to the principles outlined in the Declaration of Helsinki (as revised in 2013).

Inclusion and exclusion criteria

Inclusion criteria: (I) children aged 0 to 18 years; (II) complete clinical data available for analysis; (III) patients consented to participate in the study, and their families provided written informed consent; (IV) regular postoperative follow-up was conducted, providing at least one follow-up data point; (V) all patients received the same type of double-J stent produced by the same manufacturer.

Exclusion criteria: (I) patients found to have pyonephrosis due to ureteral obstruction during surgery; (II) incomplete clinical data; (III) patients with severe comorbidities (e.g., cardiac or pulmonary dysfunction) prior to surgery; (IV) patients who experienced severe complications (e.g., massive bleeding, organ injury) during surgery; (V) patients unable to complete postoperative follow-up.

Study variables and outcomes

The analyzed variables included age, gender, type of surgery (pelvi-ureteric junction obstruction, ureterovesical junction obstruction, vesicoureteral reflux (VUR), ureteral stones, kidney stones, and duplicated renal anomalies), duration of ureteral stent placement, history of UTI, and urine and blood culture results. Detailed patient information is shown in Table 1. Data on previous UTIs were collected from the patients’ medical records. A history of UTI was defined as any documented UTI episode within the past year prior to the surgery. This variable was included in the analysis to assess its potential impact on the incidence of FUSAUTI.

The diagnosis of FUSAUTI was based on the standardized criteria established by the Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN) for device-associated infections (8). According to CDC/NHSN criteria, a UTI associated with an indwelling ureteral stent is defined as follows: (I) fever: a body temperature greater than 38.0 ℃ (100.4 ℉) without another identifiable source of infection; (II) urinalysis: presence of pyuria, defined as a leukocyte count greater than 10 per high-power field (HPF) in urine microscopy; (III) urine culture: a positive urine culture with a bacterial count exceeding 100,000 colony-forming units per milliliter (CFU/mL) of no more than two species of microorganisms. In addition to the CDC/NHSN criteria, we also considered the following clinical symptoms: urinary urgency, frequency, dysuria, or flank pain. Patients meeting the above criteria were diagnosed with FUSAUTI.

Postoperative monitoring and follow-up

Patients’ body temperatures were monitored every 6 hours for the first 48 hours postoperatively and then twice daily until discharge. Fever >38.0 ℃ was recorded and investigated. Urine cultures were obtained at baseline (stent placement), 48 hours postoperatively, and whenever infection was suspected (e.g., fever >38.0 ℃ or urinary symptoms). Blood cultures were performed in cases of persistent fever or signs of systemic infection. Empirical antibiotics were initiated if infection was suspected. New or worsening urinary symptoms (e.g., dysuria, hematuria) prompted immediate urine culture and treatment as needed. Asymptomatic bacteriuria (>100,000 CFU/mL) was managed based on pathogen susceptibility. After discharge, patients were followed up at 1 week, 2 weeks, 1 month, and 2 months postoperatively. During each follow-up visit, patients underwent a clinical evaluation, including assessment of urinary symptoms (e.g., dysuria, frequency, urgency) and measurement of body temperature. Urine cultures were repeated at each follow-up visit to monitor for asymptomatic bacteriuria or recurrent UTIs. Stent removal, typically at 4–8 weeks postoperatively, was guided by clinical resolution and infection status.

Statistical analysis

Data analysis was conducted using SPSS version 22.0. Categorical variables were presented as case numbers and percentages, and group differences were analyzed using the Chi-squared test. Continuous variables that followed a normal distribution were expressed as mean ± standard deviation (SD), with intergroup comparisons performed using independent samples t-test; non-normally distributed continuous variables were presented as median and interquartile range (IQR). A P value of <0.05 was considered statistically significant.

Missing data were handled using multiple imputation for continuous variables and complete case analysis for categorical variables. Variables with more than 10% missing data were excluded from the analysis. Sensitivity analyses were conducted to compare imputed and complete case datasets, showing no significant differences. To identify independent risk factors for FUSAUTI, a multivariable logistic regression analysis was performed. Variables included in the model were age, gender, previous UTI history, type of surgery, duration of stent placement, and laterality of stent placement. The results were expressed as odds ratios (ORs) with 95% confidence interval (CIs). The model’s goodness-of-fit was assessed using the Hosmer-Lemeshow test, and no significant lack of fit was observed (P>0.05).

Results

A total of 355 pediatric patients who underwent ureteral stent placement were included in this study, of which 32 cases developed FUSAUTI, resulting in an incidence rate of 9.01%. All diagnosed cases exhibited fever greater than 38.0 ℃, pyuria (leukocyte count >10/HPF), and significant bacteriuria (bacterial count >100,000 CFU/mL) in urine culture. There was no significant difference in median age between the two groups, with ages of 6.9 years (non-infection group) and 6.1 years (infection group), respectively (P=0.34). The proportion of female patients in the infection group was higher than that in the non-infection group, at 34.4% and 18.6%, respectively; this difference was statistically significant (P=0.04). A significant difference was observed in the prevalence of previous UTIs between the infection and non-infection groups. In the infection group, 37.5% (12/32) of patients had a history of UTI, compared to 20.7% (67/323) in the non-infection group (P=0.03). This suggests that a history of UTI may be a significant risk factor for the development of FUSAUTI. There were no significant differences in the types of surgery [ureteropelvic junction obstruction (UPJO), vesicoureteral junction obstruction (VPJO), VUR, ureteral stones, etc.] between the two groups (P=0.52). The distribution of left-sided, right-sided, and bilateral stent placements showed no significant difference (P=0.15). Among the infection group, 62.5% of patients were classified as ASA I, 31.3% as ASA II, and 6.2% as ASA III, while in the non-infection group, 65.0% were ASA I, 30.0% were ASA II, and 5.0% were ASA III. There was no significant difference in ASA classification between the two groups (P=0.46). The duration of stent placement in the non-infection group was 48.2±9.7 days and in the infection group was 52.7±9.6 days, with statistically significant difference (P=0.01). The multivariable logistic regression analysis revealed that female gender was significantly associated with an increased risk of FUSAUTI (OR =2.15, 95% CI: 1.12–4.10, P=0.02). Previous UTI history was also identified as an independent risk factor (OR =7.31, 95% CI: 1.894–28.214, P=0.004). Additionally, longer stent placement duration was linked to a higher infection risk (OR =1.05 per additional day, 95% CI: 1.01–1.09, P=0.01). In contrast, age, type of surgery, and laterality of stent placement were not significantly associated with FUSAUTI in the multivariable analysis. Detailed information is presented in Table 2.

Among the 32 patients with FUSAUTI, Escherichia coli accounted for 40.6% (13/32) of urine cultures, followed by Enterococcus at 31.2% (10/32) and Pseudomonas aeruginosa at 9.4% (3/32). Other pathogens included Candida species (spp.) (2 cases), Klebsiella spp. (2 cases), Proteus spp. (1 case), and Morganella spp. (1 case). Among the 10 patients with positive blood cultures, Escherichia coli was the most common pathogen, accounting for 60.0% (6/10), followed by Enterococcus at 30.0% (3/10). Additionally, one case of Pseudomonas aeruginosa was isolated. These results indicate that Escherichia coli and Enterococcus are the primary pathogens responsible for FUSAUTI, with some patients exhibiting infections from Pseudomonas aeruginosa and other pathogens. Detailed information is shown in Table 3.

Antimicrobial susceptibility testing results indicated that, among the isolates, Escherichia coli and Pseudomonas aeruginosa comprised a significant proportion of Gram-negative bacteria, with sensitive drugs including cefepime, meropenem, cefoperazone/sulbactam, ertapenem, piperacillin/tazobactam, and nitrofurantoin. Among Gram-positive bacteria, Enterococcus faecalis was predominant, with sensitive drugs including vancomycin, tigecycline, meropenem, and teicoplanin. The primary fungal isolate was Candida albicans, with sensitive drugs including voriconazole and fluconazole.

Discussion

The results of this study indicated that the incidence of FUSAUTI in children following urological surgery was 9.01% (32 out of 355 cases). Previous studies have reported FUSAUTI rates ranging from 6% to 18% (9,10). The incidence rate of FUSAUTI in our study (9.01%) falls within the reported range, suggesting that variations in patient populations, definitions, and follow-up management across different studies may influence reported infection rates. Despite differences in infection rates, ureteral stent-associated UTIs remain significant complications in clinical practice. In children, infections can adversely affect urinary system development and may lead to more severe complications, such as sepsis and renal impairment (11). Febrile ureteral stent infections in children typically refer to the occurrence of fever and other symptoms of UTI following stent placement. Such infections may be caused by bacteria or fungi, with common bacterial pathogens including Escherichia coli and Pseudomonas aeruginosa, while Candida spp. are the most frequently encountered fungi (12). Typical symptoms include fever, urinary symptoms (such as frequency, urgency, and dysuria), abdominal pain, abnormal urine (such as cloudiness or hematuria), and other nonspecific symptoms (13,14). Treatment generally involves the use of antibiotics or antifungal medications, determined by culture and sensitivity results, and may also require considering the removal of the ureteral stent, alongside hydration and supportive therapy for the patient. Due to anatomical differences in the urinary systems of male and female patients, females have shorter, wider, and straighter urethras compared to males, and their urethras are located closer to the anus, which increases the risk of ascending urinary infections in females (15). Therefore, the risk of UTI and positive bacterial cultures post-stent placement is higher in females than in males. A study suggests that female patients are more likely to have bacterial adhesion on ureteral stents, promoting biofilm formation (16).

Our analysis revealed a significant difference in the prevalence of previous UTIs between the infection and non-infection groups, with 37.5% of patients in the infection group having a history of UTI compared to 20.7% in the non-infection group. This finding suggests that a history of UTI may be a significant risk factor for the development of FUSAUTI. Patients with recurrent UTIs may have underlying anatomical or functional abnormalities in the urinary tract, such as bladder dysfunction, which predispose them to recurrent infections (17). Additionally, previous UTIs may lead to the colonization of uropathogenic bacteria in the urinary tract, increasing the risk of infection following stent placement. Therefore, patients with a history of UTI should be considered a high-risk group for FUSAUTI, and preventive measures, such as prophylactic antibiotics or closer monitoring during the stent placement period, may be warranted.

Ureteral stents are slender, tubular medical devices typically made from flexible materials such as polyurethane, silicone, or polyethylene, designed for temporary or long-term placement within the ureters to maintain patency and facilitate urine flow from the kidneys to the bladder (18). These stents are commonly used during percutaneous nephrolithotomy, ureteroscopic procedures, or other situations that may lead to ureteral obstruction or injury. In pediatric cases, ureteral stent placement is often seen postoperatively in congenital urinary tract anomaly surgeries, such as obstructive uropathy (UPJO), VUR, or following kidney or ureteral stone procedures. Ureteral stents serve dual functions of support and drainage, preventing ureteral narrowing while promoting urine excretion, thus playing a crucial role in treating urinary tract diseases and postoperative recovery (19). Clinically, the typical duration for a double-J stent is 2 to 6 weeks; however, due to the complexity of patient conditions, some may require stent placement for up to six months to a year. Stent placement may cause symptoms such as pain, bladder irritation, hematuria, and fever, with stent-associated infections being a common complication that can lead to life-threatening ascending urinary sepsis (20). Bacterial growth and colonization on ureteral stents is a critical issue, as they can adhere to exposed surfaces. Once bacteria attach to the stent surface, they may produce fibrin, lipoproteins, and polysaccharide matrices, forming biofilms, commonly referred to as bacterial biofilms (21). Reports indicate that the bacterial colonization rate on ureteral stents is approximately 24% after 4 weeks, increasing to about 33% after 4–6 weeks, and eventually around 71% thereafter (22). In this study, prolonged stent placement was identified as a significant risk factor for FUSAUTI, with longer indwelling times correlating with a higher infection rate. These findings highlight the importance of timely stent removal and close postoperative monitoring to mitigate infection risks.

In our study, the UTIs associated with pediatric ureteral stents predominantly involved Escherichia coli (40.6%) and Enterococcus spp. (31.3%). Based on susceptibility test results, we opted for piperacillin-tazobactam, ampicillin, and nitrofurantoin for treatment to effectively control the progression of UTIs. Once the infection was managed, we promptly removed the ureteral stent to minimize the impact of prolonged placement on the patient. Escherichia coli typically originates from the human intestine, and its toxins and adherence capabilities make it a common pathogen in UTIs, showing sensitivity to beta-lactam antibiotics, although resistance is gradually increasing. Enterococcus spp. are also commonly found in the gut; despite their lower virulence, they can still cause UTIs under certain conditions, being sensitive to penicillin but exhibiting variable resistance. For the two common bacteria, we found that nitrofurantoin demonstrated sensitivity in most susceptibility tests. Nitrofurantoin is a broad-spectrum antibacterial agent that inhibits cell division by disrupting bacterial nucleic acid synthesis and interfering with the metabolism of toxic substances, promoting bacterial death. Its localized antibacterial action at high concentrations in urine effectively suppresses UTIs (23). Other pathogens included Pseudomonas aeruginosa, Klebsiella spp., Proteus spp., and Morganella spp., all of which are Gram-negative bacteria with strong environmental adaptability and are widely present in nature but can also cause infections in humans and animals, especially under immunocompromised conditions. These bacteria typically exhibit high resistance and can form biofilms to resist antibiotic attacks, potentially producing various virulence factors. Some patients also presented with Candida spp., a fungal infection that is relatively rare compared to bacterial infections. Candida infections typically occur in individuals with weakened immune systems, those on long-term antibiotic therapy, and other susceptible populations. These infections may arise during or after ureteral stent placement, especially when patients are on broad-spectrum antibiotics or immunosuppressive agents. Candida spp. thrive well on mucosal surfaces and in moist environments, such as the urinary tract mucosa, potentially leading to UTIs under certain conditions. Treatment for such infections usually requires antifungal agents like fluconazole or itraconazole.

The limitations of this study include its retrospective design, which may lead to selection bias and affect the generalizability of the results. Although 355 pediatric cases were included, the sample size is relatively small and may not adequately represent the broader pediatric population. Being a single-center study introduces additional limitations. Furthermore, there may be unidentified confounding factors, such as patients’ lifestyle or underlying conditions, which could also influence the accuracy of the results. Lastly, the sensitivity and specificity of the urine and blood culture testing methods may be limited, potentially impacting the reliability of the findings.

Conclusions

This study revealed a 9.01% incidence of FUSAUTI after pediatric urological surgery. Female gender and a history of previous UTIs were identified as significant risk factors for FUSAUTI, while disease severity, as assessed by the ASA classification, did not show a significant association. Enhanced postoperative management, including standardized antibiotic prophylaxis, close monitoring during stent placement, and prompt removal of stents when clinically indicated, is crucial for high-risk patients. Regular infection monitoring can help reduce FUSAUTI occurrence. A comprehensive pre-surgical assessment and personalized postoperative care plans based on risk factors are recommended to improve treatment outcomes and patient prognosis.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-538/rc

Data Sharing Statement: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-538/dss

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-538/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-538/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was approved by the Ethics Committee of Anhui Provincial Children’s Hospital (No. EYLL-2023-06-009). All participants’ legal guardians provided written informed consent. All research involving humans (individuals, samples, or data) was conducted according to the principles outlined in the Declaration of Helsinki (as revised in 2013).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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