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Abstract
Objectives The objectives are to determine the prevalence of urinary tract infection (UTI) and associated factors among patients diagnosed with benign prostatic hyperplasia and prostate cancer.
Design Hospital-based cross-sectional study.
Settings Urology clinic and urology ward at Muhimbili National Hospital, which is the main tertiary hospital in Tanzania’s largest city.
Participants Patients with benign prostate hyperplasia and prostate cancer presenting with genitourinary symptoms.
Main outcome measure The primary outcome was the occurrence of UTI and factors associated with UTI in patients with benign prostatic hyperplasia and prostate cancer.
Results 402 participants were enrolled, with a median age of 68 years and IQR of 61–75 years. The proportion of UTI was 46.5% (95% CI 41.56% to 51.53%). UTI was more prevalent among inpatients, patients with indwelling urinary catheters, patients with prostate size>80 cm3 and those with residual urine volume of >100 mL. In multivariate analysis, age>60 years (adjusted OR (aOR)=2.0, 95% CI 1.13 to 3.55, p=0.018), post-void residual urine volume>100 mL (aOR 1.32, 95% CI 0.67 to 2.59 p=0.001), patient with incomplete bladder emptying (aOR=2.57, 95% CI 1.44 to 4.59, p=0.001) and prolonged catheter duration (aOR=1.24, 95% CI 1.11 to 1.38, p=0.005) were significantly associated with UTI.
Conclusion Almost half of the patients with an enlarged prostate and genitourinary symptoms had a laboratory-confirmed UTI. The risk of UTI increases with age, incomplete bladder emptying and increased duration of catheterisation. A 1-day increase in the duration of catheterisation increased the risk of UTI by 24%.
- Urinary tract infections
- Prostate disease
- Urinary incontinences
Data availability statement
Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplemental information.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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STRENGTHS AND LIMITATIONS OF THIS STUDY
Using the Analytical Profile Index as an additional identification test increased the accuracy of identifying Gram-negative rods.
We conducted a receiver-operating characteristic curve analysis to predict the duration of the catheter use, in days, at risk of developing a urinary tract infection (UTI) in men with benign prostate hyperplasia and prostate cancer, which was not done in similar studies.
We enrolled patients with enlarged prostate and genitourinary symptoms without determining whether the genital symptoms were solely due to obstruction caused by the enlarged prostate, without microbial infection, consequently affecting the UTI detection rate.
Introduction
Urinary tract infection (UTI) in adult men is often complicated and caused by structural or functional abnormalities of the genitourinary tract. The abnormalities may be due to benign prostate hyperplasia (BPH), prostate cancer, bladder stones or catheterisation.1 UTI related to an enlarged prostate occurs because the bladder does not empty completely, allowing urine to stagnate and creating a suitable environment for pathogens to grow.2 The risk for UTI increases with a larger prostate size, leading to a higher postvoid residual (PVR) urine volume.3
Urinary catheterisation is commonly used to relieve retained urine in the urinary bladder obstructed by an enlarged prostate gland.4 Prolonged use of urinary catheters poses a major risk for UTI.5 However, the exact duration for urinary catheters to cause UTI is unknown.5 6 A study conducted at Bugando Medical Centre in Mwanza reported that 39% of patients had retained urinary catheters beyond the recommended time, leading to an increased risk for UTI with the duration of catheter use.5
The occurrence of UTI in patients with BPH and prostate cancer varies across different studies and populations.7 8 Isolated bacteria causing UTI have been reported to show a high level of resistance to prescribed antimicrobials, thus complicating the management of UTI in this population.9 Identifying the factors that make patients more prone to UTI and taking appropriate measures is crucial in developing effective strategies to prevent UTI in this group, and therefore improving patient lifestyle and outcomes. Therefore, our current study aims to assess the magnitude of UTI, identify the factors associated with them and determine the optimal duration for indwelling urinary catheter use with a low risk of UTI.
Materials and methods
Study design and setting
The study was a hospital-based cross-sectional design conducted at Muhimbili National Hospital (MNH) in Dar es Salaam. MNH, which is a referral and teaching hospital, has a 1500-bed capacity and is the largest tertiary hospital in Tanzania. It sees over 1000 outpatients per week and serves approximately seven million people in the Dar es Salaam region.
Enrolment and sample size estimation
The study involved male patients who had been clinically diagnosed with BPH or prostate cancer through digital rectal examination. We only included patients who had genitourinary symptoms within the past month and were mentally competent to give consent. Patients with a urinary catheter for more than 1 month and those with other causes of bladder outlet obstruction, such as urethral stricture, urolithiasis, bladder cancer and neurogenic causes, were excluded from the study.
The minimum sample size was 380, calculated using the Kish and Leslie formula (1965), considering the prevalence of 44.7% in Niger, in 2016. Participants were enrolled consecutively from August 2021 to January 2022 until the predetermined sample size was reached
Data collection
We used a structured questionnaire to gather information about the participants’ sociodemographic and clinical details, as well as genitourinary symptoms. The questionnaire included inquiries about the participants’ age and place of residence of participants, recent instrumentation (within 30 days of data collection) and duration of catheter use in days, recent urological surgeries (within 30 days of data collection) and recent use of antibiotics (within 30 days of data collection). We also obtained radiological and histopathological results from the patient’s records.
Urine collection
Mid-stream urine was collected for culture from non-catheterised patients. For catheterised patients, a clump was placed above the port to allow urine to collect in the bladder, followed by disinfection of the port with 70% alcohol and iodine solution and clump release to collect urine into a sterile urine container. 10 mL of urine were collected and sent to the microbiology laboratory at MNH for processing immediately.
Bacterial isolation and identification
Urine was inoculated onto cysteine lactose electrolyte deficient agar and blood agar plates using a 1 µL loop and incubated aerobically at 37°C for 18–24 hours. Identification from culture plates with significant bacteria growth of ≥105 (colony-forming unit/mL) based on Gram stain characteristics, colony morphology and biochemical tests as described by Mahon et al.10 Gram-positive bacteria were identified by catalase, coagulase and DNase (Remel Europe, Dartford, UK), while Gram-negative bacteria were identified by oxidase, Kligler iron agar, urease, citrate and sulphur, indole and motility (Oxoid, Hampshire, UK). Analytical Profile Index (API-20E) (Biomerieux, France) was used to identify Gram-negative rods further. Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were used for quality control of culture media and biochemical tests.
Statistical analysis
Data analysis was performed using Statistical Package for the Social Sciences V.27. We used frequencies and percentages for categorical variables and median (IQR) for continuous variables. The χ2 test was used to assess the difference in categorical variables. We used a receiver operating characteristics (ROC) to determine the appropriate duration of urinary catheter stay to prevent UTI. A univariate regression model was used to identify the factors associated with UTI, and factors with a p value≤0.2 in a univariate model were considered for the multivariate logistic regression analysis. A p value of <0.05 was considered to be statistically significant.
Reporting guideline
This study adhered to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines for cross-sectional studies, which provide a checklist for reporting observational studies. The checklist comprises key components that should be included in the report, including study design, sampling procedure, data collection and statistical analysis. The authors have attentively reviewed the checklist to make sure that suitable items have been included. The authors used a structured data collection tool to collect information from all study participants and used suitable statistical methods to analyse data and formulate conclusions.
Patient and public involvement
Patients and the public were not involved in this research design, conduct, reporting or dissemination plans.
Results
Description of study participants
In this study, a total of 402 participants were enrolled. The median age of the participants was 68, and the IQR was 61 and 75 years. The majority of the participants were from the outpatient (227/402, 56.2%). BPH was the most common prostatic disease, affecting 70.4% of the participants. The median prostate size measured using ultrasonography was 43 cm3 (IQR was 24.0–74.8). Most participants (46.5%) had a prostate volume of 40 cm3, while 19.1% had a PVR urine volume of ≥100 mL. Among the participants, 40% (161/402) had undergone invasive urological instrumentation, and the urinary catheter was the most invasive instrument used 155/161 (96.3%) while cystoscopy accounted for 3.7%.
The proportion of UTI among study participants
The overall proportion of laboratory-confirmed UTI was 46.5% (95% CI 41.56% to 51.53%). UTI was found more in inpatients (103, 58.3%) than in outpatients (85, 37.4%), p<0.001. UTI was significantly higher among catheterised patients (85, 70.2%) than non-catheterised patients (102, 36.3%), p<0.001. Patients who had prostate size more than 80 cm3 had a significantly higher proportion of UTI (55, 65.5%) than those with prostate size less than 40 cm3 (66, 35.5%), p=0.001. Those with a PVR urine volume of more than 100 mL had a higher proportion of UTI (25, 47.2%) than those with a urine volume of less than 100 mL (74, 32.9%), p=0.051. Patients who had undergone instrumentation had a significantly higher proportion of UTI (104, 65.4%) than those who did not undergo invasive urological instrumentation (82, 33.9%), p=0.001. In comparison, there was no significant difference in UTI among patients with BPH 127 (44.9%) and prostate cancer (60, 50.4%), p=0.309 and among patients who had undergone recent urological surgery (53, 52.5%) compared with those who did not undergo any urological surgery (134, 44.5%), p=0.165 (table 1).
Proportion of UTI among men with BPH and prostate cancer at Muhimbili National Hospital
Factors associated with UTI
In univariate analysis, patients aged>60 years had two times the odds of having UTI compared with those aged<60 years (crude OR (cOR)=2.17, 95% CI 1.50 to 3.37, p<0.001). Inpatients were observed to have two times the odds of having UTI compared with outpatients (cOR=2.33, 95% CI 1.56 to 3.49, p<0.001). Patients with incomplete bladder emptying (cOR=2.13, 95% CI 1.43 to 3.17, p<0.001) and those with recent hospitalisation (cOR=2.18, 95% CI 1.40 to 3.42, p<0.001) were also found to have approximately two times the odds of having UTI. Moreover, patients with a prostate size>80 cm3 (cOR=3.45, 95% CI 2.12 to 5.96, p<0.001) and those who had undergone invasive urological instrumentation (cOR=3.65, 95% CI 2.39 to 5.55, p<0.001) were observed to have approximately three times the odds of having a UTI.
In multivariate analysis, patients aged>60 years had two times the odds of having a UTI compared with those aged<60 years (aOR=2.0, 95% CI 1.13 to 3.55, p=0.018). Patients with PVR urine volume of more than 100 mL had a higher risk of having UTI than those with PVR urine volume of <100 mL (aOR=1.32, 95% CI 0.67 to 2.59, p=0.001). Patients with incomplete bladder emptying had two times the odds of having a UTI compared with those with complete bladder emptying (aOR=2.57, 95% CI 1.44 to 4.59, p=0.001). Additionally, the odds of UTI increased by 24% for each 1-day increase in the duration of catheter use (aOR=1.24, 95% CI 1.11 to 1.38, p=0.005) (table 2).
Factors associated with UTI among patients with BPH and prostate cancer at Muhimbili National Hospital
Risk for UTI in indwelling catheter
An ROC curve illustrating the development of UTIs based on the duration of a urinary catheter is depicted in figure 1. The area under the curve was 0.709 (95% CI, 0.67 to 0.79, p<0.001), with the optimal cut-off value being 7 days. Table 3 shows data on the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for UTI at various cut-off values. At the optimal cut-off value of 7 days, the sensitivity, specificity, PPV and NPV were 71.15%, 54.5%, 74.5% and 50%, respectively (table 3).
Receiver-operating characteristics curve for inserted urinary catheter-associated urinary tract infection based on the number of catheter days for men with benign prostate hyperplasia and prostate cancer at Muhimbili National Hospital.
Sensitivity, specificity, positive predictive value and negative predictive value for catheter-associated urinary tract infection at different cut-off values of catheter days
Discussion
This study found that out of 100 patients with an enlarged prostate and urinary symptoms, 46 had a laboratory-confirmed UTI. Patients over 60 years old and those with incomplete bladder emptying were found to be at a higher risk of developing UTI. This study also found that the longer the urinary catheter was in place, the greater the risk of developing a UTI, with a 24% increase in risk for each day the catheter was used. Incomplete bladder emptying can lead to bacterial growth, increasing the likelihood of developing a UTI. For these patients, corrective measures such as surgery may be surgery may be necessary. While catheterisation can help with incomplete bladder emptying, the findings suggest that it should not be prolonged as the risk of UTI increases with longer catheter use.
The proportion of UTI in patients with an enlarged prostate was consistent with a report by Agbugui et al, which found a 44.7% UTI proportion.3 9 However, Ghana reported a higher proportion of UTI (76.6%) among male patients with BPH having urethral catheters.11 Other studies in Austria, Saudi Arabia and Spain reported lower UTI proportions at 13.6%, 15% and 20.6%, respectively.12–14 The differences in proportions of UTI may be due to differences in geographical location, climatic conditions, study designs and the population studied. The high proportion of UTI in our study may be attributed to instrumentation procedures, which are a risk factor for UTI. As the prostate enlarges due to physiological changes, it obstructs urine outflow from the bladder through the urethra, creating an environment for bacteria to grow and cause infected urine, leading to UTI. Frequent hospital admissions expose these patients to colonisation and infection with multidrug resistant bacteria, which may cause difficulty in treating UTIs in these patients.4 15 16
According to this study, there was a significant association between UTIs and the age of patients. Patients over 60 years had a higher likelihood of infection as compared with those who were 60 years or younger. Other studies have shown similar results, linking the risk of UTI with advanced age.1 13 Oshodi et al reported an increase in the proportion of UTIs with age in their study, with the highest proportion being 70.6% among patients aged 80 years and older.17 The increase in UTI with age may be due to weakened immune systems and the presence of comorbidities in older patients. Additionally, in advanced age, there is a decrease in the concentration of zinc in the prostate due to impaired zinc uptake by body cells.18 Zinc has been found to have antibacterial properties, which can help prevent infections related to the prostate gland and UTIs among men.19
Incomplete emptying of the urinary bladder, leading to urine retention due to obstruction, has been significantly associated with UTI in this study. This is consistent with previous findings reported by Hyens that urine stasis is a risk factor for developing UTI.20 Urine retention in these patients may be worsened by factors such as enlargement of the prostate gland, cancers metastasising to the prostate gland and urethral stricture as a result of urethral trauma due to instrumentation, and advanced age, which may lead to degeneration of the brain, affecting bladder innervation and consequently, bladder emptying.4
In our study, a PVR>100 mL was significantly associated with UTI among these patients. Incomplete bladder emptying also results in PVR urine volume, which can harbour bacteria and predispose to UTI.20 Additionally, other studies reported that UTI was prevalent in patients with significantly high mean PVR; however, no specific cut-off value was determined to predict positive urine culture.3 21 Another study reported similar findings where men without symptoms but with a PVR of 180 mL were at high risk for UTI.3
Several studies have shown that as the prostate size increases, there is a correlation with a larger PVR, which can potentially lead to an increased risk of UTI.12 22 23 A recent study by Righetto et al showed that patients with renal transplants and moderate lower urinary tract symptoms benefit from urodynamic evaluation and early trans-urethral resection of the prostate, whereby early surgical resolution of the prostate obstruction can lead to a reduced rate of UTI.24 However, in our study, we found that prostate size was not associated with UTI. Similar findings have been reported in other studies on UTI among patients with BPH and prostate cancer, whereby prostate size was not an independent predictor of UTI.7 9 These findings may be attributed to factors such as settings and practices including the use of antimicrobial prophylaxis in our patients to prevent UTIs.
Catheterisation is usually performed to drain urine due to retention in patients with enlarged prostates, and bladder irrigation following surgery.4 However, our current study has shown that prolonged catheterisation beyond 7 days increases the risk of developing UTI. Several studies have also reported that the risk of UTI increases with longer catheterisation periods.5 25 The WHO guideline recommends 7–10 days of urinary catheterisation after urinary surgical repair in short-term catheterisation.26 The Health Infection Control Practices Advisory Committee guideline by the Centre for Disease Control does not recommend routine changing of indwelling catheters or drainage bags at fixed intervals for catheter change.27 28 Nevertheless, since the medical practices and patient characteristics have evolved, our study suggests 7–10 days of urinary catheterisation among patients with BPH and prostate cancer to prevent UTI. It is important to note that multi-centre studies involving larger populations should be conducted to provide more comprehensive findings. This will be crucial in establishing evidence-based guidelines to determine the appropriate duration of catheterisation among this patient population. A recent study showed that in kidney-transplanted patients with lower urinary tract symptoms, early removal of the bladder catheter can lead to a reduced rate of infection and possible impairment of the transplanted kidney.24
One of the strengths of our study is that it includes the duration of the catheterisation in days at risk of UTI for men with BPH and prostate cancer, which was not addressed in previous studies. However, we faced challenges in determining whether genitourinary symptoms in patients with BPH and prostate cancer were solely due to an enlarged prostate causing obstruction, without any microbial infection, and this may have impacted the detection rate of UTIs.
Conclusion
Our study shows, at the multivariate analysis, a positive correlation between advanced patients’ age, PVR>100 mL, incomplete bladder emptying, days of catheterisation higher than 7 days and UTI among patients with prostate enlargement and genitourinary symptoms. Intervention to resolve urinary obstruction, such as prostate surgery should not be delayed in these patients, to achieve prompt catheter removal and prevention of clinically significant UTIs.
Data availability statement
Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplemental information.
Ethics statements
Patient consent for publication
Ethics approval
The ethical approval was obtained from the Senate Research and Publications Committee of the Muhimbili University of Health and Allied Sciences (reference number DA.282/298/01.C/). Participants were requested to sign informed consent before enrolment in the study.
Acknowledgments
We thank the MNH administration and the department of urology at MNH for their support. We thank the study participants and CPL staff for their technical assistance.
References
Footnotes
Contributors EMN, MM and AJ contributed to conceptualisation and data collection. EMN, MM, PPK and AS performed the formal analysis. EMN, MM, OVN, JM, AS, AGM, PPK, EL and AJ participated in the writing and thorough perusal of the manuscript and the approved final version. EMN is the guarantor of the study. The lead author (the manuscript’s guarantor) affirms that the manuscript is an honest, accurate and transparent account of the study being reported, that no important aspects of the study have been omitted and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
Funding This study received financial support from the Good Samaritan Foundation via the department of microbiology, Radboud University Medical Centre, Netherlands. The funder had no contribution to study design selection, data collection, analysis, interpretation and manuscript writing. There is no grant number for this study.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.