Introduction
The rise in urological diseases had resulted in an increased demand for urological diagnostic procedures and treatment interventions. Postoperative infections had become significant complications, with reported rates ranging from 1.7% to 18.8% for the upper urinary tract related procedures including percutaneous nephrolithotomy (PCNL), ureteroscopy (URS), and retrograde intrarenal surgery (RIRS), and 2.6% to 13.5% for the lower urinary tract related procedures including transrectal ultrasound (TRUS) and biopsy of the prostate, transurethral resection of the prostate (TURP), holmium laser enucleation of the prostate (HoLEP), and transurethral resection of bladder tumor (TURBT). Reference Zhang, Jiang and Gao1–Reference Dybowski, Bres-Niewada and Rzeszutko4 Among the infections after prostatic procedures, the most prevalent pathogens were Escherichia coli (15.97%), Pseudomonas aeruginosa (10.76%), and Enterococcus faecalis (9.72%), where the most prevalent pathogens for PCNL were Escherichia coli (43.9%), Enterococcus faecalis (9.2%), and Klebsiella pneumoniae (5.6%). Reference Zhang, Jiang and Gao1–Reference Elsaqa, Dowd, El Mekresh, Doersch and El Tayeb6 In addition, the increase prevalence of extended spectrum beta-lactamase (ESBL) or extended spectrum cephalosporinase (ESC) pathogens infections had been in arising in the Southeast Asia, where the prevalence of ESBL/ESC infections after urological procedures were reported of 59.5%. Reference Dumford, Suwantarat and Bhasker7,Reference Zaytoun, Vargo, Rajan, Berglund, Gordon and Jones8 Risk factors for ESBL/ ESC infections have been identified such as a history of antibiotic use in the past 3 months, recent hospital admissions, prior urinary tract infections (UTIs), and positive urine culture screening without clinical signs of urinary tract infections before the procedures (asymptomatic bacteriuria). Reference Lin, Yang and Ye2–Reference Son, Dalton and Daidone9 The consequences of postoperative infections resulted in prolonged hospital stays, multidrug-resistant (MDR) bacterial infections, and increased costs of treatment.
Given the ongoing challenges of postoperative infections, this study aimed to identify specific risk factors contributing to infections after elective urological procedures in patients with negative urine culture screening. Furthermore, the study results would be determined the rate of the infection and provided valuable insights to improve preoperative management and patient outcomes especially in the endemic area of MDR bacterial infections.
Methods
We conducted a retrospective cohort study, including patients aged ≥18 years who underwent elective urological procedures (TRUS and biopsy of the prostate, TURP, HoLEP, PCNL, URS, RIRS, and TURBT) at Thammasat University Hospital (TUH), a 750-beds tertiary care hospital, Thailand. The study patients were identified from ICD-9 of urological procedures between January 1, 2021 and September 30, 2023. The electronic medical records of all patients were reviewed for demographic characteristics, underlying medical diseases, history of recent hospital admissions, antibiotic use and prior UTIs within 3 months, prior urological procedures within the past year, retention of Foley catheter prior to the procedure, American Society of Anesthesiologists (ASA) physical status classification system, Metabolic equivalents (METS) score, Revised Cardiac Risk Index (RCRI) for preoperative risk, type of antibiotic prophylaxis, type and duration of the urological procedure, volume of the blood loss, postintervention infections, microbiological culture results, length of hospital stay and follow-up visit. As the urological procedure protocol, all patients had urological evaluation and urine culture screening prior to the procedures. For the patients with negative urine culture screening, oral levofloxacin would be prescribed as antibiotic prophylaxis for TRUS and biopsy of the prostate and intravenous cefoxitin would be prescribed for other urological procedures. Posturological procedure complications were included UTI and sepsis/bacteremia. UTI was defined as patient experiencing dysuria with or without fever or suprapubic pain, with a urine culture positive for ≥105 colony-forming units/ml and no more than two species of uropathogenic microorganisms. Sepsis was diagnosed if they met two or more Systemic Inflammatory Response Syndrome criteria. Bacteremia was diagnosed if blood culture revealed microorganisms compatible with uropathogenic microorganisms.
The descriptive data were presented in number (percentage) and mean with standard deviation or median with interquartile range (IQR) depended on data distribution. Percentages were compared using χ 2 test or Fisher exact test, while the continuous data using Mann–Whitney U test. Multivariable logistic regression analysis was performed to determine risk factor independent and outcome variables. Statistical analyses were performed using SPSS version 22. This study was approved by the Ethics Committee of Thammasat University (MTU-EC-IM-0-280/66).
Results
There were 441 patients included in this study. In the study period, 55 patients (12.5%) were infected following urological procedures, while 386 patients remained uninfected. The study population had a median age of 68 years (IQR 61–74) with 356 males (80.7%). The most common comorbidities were cardiovascular disease (54%), benign prostatic hyperplasia (49.7%), and dyslipidemia (40.6%). There were 173 patients (39.2%) with a history of renal stones and 119 patients (27%) with a history previous intervention within 3 months. For the other risks of MDR bacterial infections, there were patients with previous antibiotics used in the last 3 months (8.2%), previous UTI within the last 3 months (7.9%), previous admission in the last 3 months (1.4%) and a history of foley catheter retention before procedure (1.4%). The median time from operation to the infection onset was 6 days (IQR 5–7). The median ASA physical status classification was class 2 (70.7%). The median RCRI for preoperative risk was zero (84.1%). The mean operation time was 103 minutes (IQR 70–130). The most common interventions were TRUS and biopsy of prostate (26.5%), TURBT (15.4%), and URS (13.8%) (Table 1).
Table 1. Patients characteristics
Note. IQR, interquartile range; UTI, urinary tract infection.
a Colorectal cancer; breast cancer; cholangiocarcinoma.
b Prior urological interventions within 3 months.
The antibiotic prophylaxis included levofloxacin (26.5%) and cefoxitin (73.5%). UTI occurred in 55 patients (12.5%) with 9 patients (2%) developing urosepsis. The most common microorganisms were E. coli (49%), P. aeruginosa (16.4%) and K. pneumoniae (12.7%). The pattern of MDR pathogens included ESC isolates (43.6%). The median hospital stay was 12 days (IQR 10–15) for patients with infection and 3 days (IQR 3–4) for non-infection. No fatalities were reported.
Multivariable logistic regression analysis revealed several significant risk factors for posturological procedure infections. Theses included RCRI for preoperative risk score ≥2 (OR = 10.46; 95% CI 2.36–46.28, P = .002), history of previous UTI within the last 3 months (OR = 4.95; 95% CI 2.05–11.97, P < .05), and presence of underlying chronic kidney disease (CKD) stage III–V (OR = 4.42; 95% CI 1.55–12.60, P = .005). The interventions associated with a higher risk of infections after urological procedure were PCNL (OR = 5.39; 95% CI 2.20–13.23, P < .05) (Table 2). Through multivariable logistic regression analysis of risk factor of ESC pathogens detection, there was no associations with any risk factors (Supplement 1).
Table 2. Multivariate analysis of risk factors for infection after urological procedures among patients with negative urine culture screening
Note. UTI, urinary tract infection.
Discussion
Our study had the novel finding and implications. First, we identified CKD as the important risk factor for infection following urological procedures. To our knowledge this risk factor had never been identified in the prior literature. Second, we also identified RCRI score as an important severity of illness to predict the risk for the infection. Third, our study highlighted the high prevalence of MDR bacterial infection after the procedures.
In previous studies, the risk factors associated with infection following urological procedures included a history of antibiotic usage, recent hospitalization, and urinary tract infection within the past 3 months. Reference Yang, Lin and Hong3–Reference Son, Dalton and Daidone9 One study had indicated that acute kidney injury (AKI) following PCNL procedures was correlated with infection after the procedure. Interestingly, individual who develop AKI were increased likelihood of postoperative sepsis and extended stay in the intensive care unit. Reference Reich, Adiyeke and Ozrazgat-Baslanti10 In operations with prolonged duration and comorbidities, there was an increased risk of postoperative UTI, especially among PCNL patients with a history of past UTI and Foley catheter use. Reference Dumford, Suwantarat and Bhasker7–Reference Reich, Adiyeke and Ozrazgat-Baslanti10
In our study, the RCRI for preoperative risk ≥2 was an important risk factor of infection after urological procedure. The RCRI score incorporated factor such as the type of surgical procedure with high risk profile, history of ischemic heart disease, congestive heart failure, cerebrovascular disease, preoperative treatment with insulin, and preoperative creatinine >2 mg/dL/176.8 μmol/L. These factors predicted the perioperative risk of cardiac events and identified individuals with multiple underlying diseases in vulnerable groups, which could lead to a high risk of infection following procedures.
Similar to previous study, we identified a significant proportion of MDR E.coli following urological procedures, thus underscoring the importance of implementing appropriate antibiotic prophylaxis. Reference Zhang, Jiang and Gao1–Reference Dybowski, Bres-Niewada and Rzeszutko4,Reference Dumford, Suwantarat and Bhasker7,Reference Son, Dalton and Daidone9,Reference Kittaweerat, Buaban and Tansakul11,Reference Sa-nguancharoenpong and ThaidumrongInsight12 In our study, the rate of postoperative infection was varied by type of procedures and ranged from 7.2% (TURP) to 30.9% (PCNL). In Thailand, the previous studies have been reported rate of postoperative infection ranged from 7.8% (URS) to 19.4% (transurethral anatomical enucleation of prostate). Reference Kittaweerat, Buaban and Tansakul11,Reference Sa-nguancharoenpong and ThaidumrongInsight12
There were some limitations in this study. First, this study was performed in a single hospital, which may limit generalizability of preoperative antibiotic prophylaxis. Second, we used a retrospective study design. The history of recent hospital admissions, antibiotic use and prior UTIs data outside the TUH might be unavailable. Third, the prevalence of MDR pathogens and antibiotic prophylaxis regimen would be varies in other areas based on the regional or hospital specific antibiogram data. Finally, the small sample size in this study limited our power to detect changes in outcome results.
In conclusion, CKD and the RCRI score were novel risk factors and associated with postoperative infections following urological procedures. The increasing prevalence of MDR pathogens highlighted the need for new strategies or appropriate antibiotic prophylaxis. A future study to identified additional risk factors for MDR bacterial infections should be conducted and prioritized rectal screening before urological procedures in patients with negative urine culture screening.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/ash.2025.10271.
Financial support
The authors gratefully acknowledge the financial support provided by Chulabhorn International College of Medicine Thammasat University, Contract No. 11/2559) and Thammasat University Research Grant, Thammasat University. AA and KJ was supported by Thailand Science Research and Innovation Fundamental Fund fiscal year 2024.
Competing interests
None.
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