Urinary tract infections (UTIs) are among the most common healthcare-associated infections, contributing substantially to patient morbidity, prolonged hospitalization, and increased healthcare costs. A significant proportion of these infections are related to urological interventions, particularly endourological procedures, which include ureteroscopy, percutaneous nephrolithotomy (PCNL), transurethral resection of the prostate (TURP), and cystoscopy. These procedures, while minimally invasive, can disrupt the normal urinary tract barrier and facilitate bacterial entry, leading to post-procedural bacteriuria or symptomatic infections despite aseptic precautions and prophylactic antibiotics (1–3). The incidence of post-endourological infections varies widely, reported between 2% and 20%, depending on the procedure type, patient comorbidities, pre-existing bacteriuria, and perioperative management protocols (4,5). Instrumentation of the urinary tract, the presence of indwelling catheters, prolonged operative duration, and incomplete stone clearance are known risk factors for infection (6,7). The rise of antimicrobial-resistant uropathogens further complicates the prevention and management of these infections (8). Understanding the association between various endourological procedures and post-operative urinary infections is crucial for guiding antibiotic prophylaxis, optimizing perioperative care, and improving outcomes. A prospective study design allows for accurate assessment of temporal relationships and risk factor identification under standardized clinical settings (9,10). The present prospective study aims to evaluate the incidence and determinants of urinary infections following different endourological procedures and to identify patient and procedural factors contributing to infection risk.

This was a prospective observational study conducted in the Department of Urology at Konaseema institute of medical science Amalapuram, Andhra Pradesh, India a tertiary care teaching hospital over a period of two years (December 2016 to November 2018). The study included adult patients undergoing various endourological procedures, such as cystoscopy, ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), and transurethral resection of the prostate (TURP). Institutional ethical committee approval was obtained prior to initiation of the study, and written informed consent was taken from all participants. Inclusion criteria: All patients aged 18 years and above undergoing elective or emergency endourological procedures were included, irrespective of gender. Exclusion criteria: Patients with ongoing antibiotic therapy, known immunocompromised status, or indwelling urinary catheters before admission were excluded. Patients with incomplete follow-up data were also excluded. Preoperative assessment: All patients underwent detailed clinical evaluation, including demographic data, comorbidities, indication for procedure, and prior history of urinary infections. Midstream urine samples were collected before surgery for routine microscopy, culture, and sensitivity testing. Significant bacteriuria was defined as ≥10⁵ colony forming units (CFU)/mL of a single pathogen (11). Patients with positive cultures were treated according to sensitivity results, and the procedure was delayed until urine sterility was achieved when feasible. Procedural details: Standard aseptic precautions were maintained for all procedures. Prophylactic antibiotics were administered in accordance with institutional protocol and current guidelines (12). Operative parameters, including procedure type, duration, use of stents, and intraoperative complications, were recorded. Postoperative assessment: Urine samples were collected on postoperative days 2 and 7, or earlier if the patient developed fever, dysuria, or flank pain. UTIs were diagnosed based on clinical features and positive urine culture results. The isolated organisms and their antibiotic susceptibility patterns were analyzed. Statistical analysis: Data were compiled and analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation (SD), while categorical variables were presented as frequencies and percentages. The chi-square test or Fisher’s exact test was used to assess associations between categorical variables, and Student’s t-test was applied for continuous data. Logistic regression analysis was performed to identify independent predictors of post-procedural urinary infections. A p-value <0.05 was considered statistically significant.

A total of 150 patients undergoing endourological procedures were included in this prospective study. The mean age of the study population was 52.6 ± 13.8 years, with a male-to-female ratio of 2.3:1. The types of endourological procedures performed included ureteroscopy (URS) in 45 patients (30%), percutaneous nephrolithotomy (PCNL) in 40 (26.7%), transurethral resection of the prostate (TURP) in 35 (23.3%), and cystoscopy in 30 (20%). Table 1: Distribution of Procedures and Postoperative Urinary Tract Infection (UTI) Incidence Procedure Type No. of Patients (n=150) No. with Postoperative UTI Incidence (%) Ureteroscopy (URS) 45 5 11.1 Percutaneous Nephrolithotomy (PCNL) 40 8 20.0 Transurethral Resection of Prostate (TURP) 35 6 17.1 Cystoscopy 30 2 6.7 Total 150 21 14.0 Preoperative findings: Preoperative urine cultures revealed significant bacteriuria in 18 patients (12%), predominantly caused by Escherichia coli (61.1%), Klebsiella pneumoniae (22.2%), and Enterococcus faecalis (16.7%). All patients with bacteriuria were treated before surgery, and urine sterility was confirmed prior to the procedure. Microbiological profile of postoperative infections: Among the 21 patients who developed postoperative UTIs, E. coli remained the predominant pathogen (47.6%), followed by Pseudomonas aeruginosa (23.8%) and Klebsiella pneumoniae (19%). Most isolates exhibited resistance to fluoroquinolones and third-generation cephalosporins but were sensitive to carbapenems and aminoglycosides. Table 2: Bacterial Isolates and Antibiotic Resistance Pattern Organism Frequency (n=21) Fluoroquinolone Resistance (%) Cephalosporin Resistance (%) Carbapenem Sensitivity (%) Aminoglycoside Sensitivity (%) E. coli 10 (47.6%) 80 70 90 85 Pseudomonas aeruginosa 5 (23.8%) 60 65 95 80 Klebsiella pneumoniae 4 (19.0%) 75 70 88 84 Enterococcus faecalis 2 (9.6%) - - - 100 Risk factors for postoperative UTI: Patients with diabetes mellitus, preoperative catheterization, or longer operative duration (>90 minutes) showed a significantly higher incidence of postoperative infection (p < 0.05). Table 3: Association Between Risk Factors and Postoperative UTI Risk Factor Total (n=150) UTI Present (n=21) UTI Absent (n=129) p-value Diabetes mellitus 38 10 (26.3%) 28 (21.7%) 0.03* Operative time >90 min 42 11 (26.2%) 31 (24.0%) 0.02* Preoperative catheterization 25 7 (28.0%) 18 (14.0%) 0.04* Stone size >2 cm (PCNL) 20 6 (30.0%) 14 (11.0%) 0.01* *Statistically significant (p < 0.05) Predictors of infection: Multivariate logistic regression analysis identified diabetes mellitus (OR 2.9, 95% CI 1.1–7.5), operative time >90 minutes (OR 3.4, 95% CI 1.3–8.9), and stone size >2 cm (OR 2.7, 95% CI 1.0–7.0) as independent predictors of postoperative infection. Hospital stay and outcomes: The mean hospital stay was 4.8 ± 2.3 days, significantly longer in patients with infection (7.1 ± 2.8 days) compared to those without (4.2 ± 1.6 days, p < 0.001). All infected patients recovered with culture-guided antibiotic therapy, and no mortality was observed.

In the present prospective study, the overall incidence of postoperative urinary tract infection following endourological procedures was 14%, which falls within the range reported in previous studies on infectious complications after stone surgery and related endourological interventions [13-15,22]. The relatively higher infection rates observed after more invasive procedures, particularly percutaneous nephrolithotomy, may be explained by greater tissue manipulation, increased intrarenal pressure, prolonged instrumentation, and the complexity of stone disease. Michel et al. documented that complications after percutaneous nephrolithotomy are closely linked to procedural invasiveness and operative factors [13], while Tambo et al. showed that bacterial infection after ureteroscopic lithotripsy is influenced by operative and patient-related variables [15]. Likewise, the CROES global study by de la Rosette et al. highlighted that complication risk after PCNL is multifactorial and rises with increasing procedural complexity [22]. The present study identified diabetes mellitus, operative duration exceeding 90 minutes, and large stone burden greater than 2 cm as significant predictors of postoperative infection. These findings are biologically plausible and are supported by the published literature. Bag et al. demonstrated that patients undergoing PCNL remain vulnerable to upper tract infection and urosepsis, emphasizing the importance of preoperative infection control in high-risk settings [14]. Tambo et al. also reported that prolonged instrumentation and perioperative factors contribute substantially to infectious morbidity after ureteroscopic procedures [15]. In addition, Omar et al. stressed that urosepsis after ureteroscopy is usually the result of an interplay between host susceptibility, stone-related microbial colonization, and intraoperative factors, rather than a single isolated cause [21]. Thus, the risk profile observed in this study is consistent with the broader understanding that both patient comorbidity and procedure burden drive postoperative infectious outcomes. An important observation in the present study was that postoperative infection occurred even in some patients with sterile preoperative urine cultures. This suggests that negative bladder urine culture does not always exclude the presence of occult infection within the upper urinary tract or on instrument surfaces. Costerton et al. established that bacterial biofilms are a major cause of persistent infection because they protect microorganisms from host defenses and antimicrobial therapy [16]. In the urological setting, Tenke et al. further elaborated that biofilm formation on catheters, stents, and endourological equipment can serve as a persistent nidus for postoperative infection [17]. These mechanisms may explain why infection can still develop despite apparently adequate preoperative preparation. The present findings therefore reinforce the importance of meticulous sterilization, minimization of catheter dwell time, and careful postoperative monitoring. The microbial spectrum isolated in this study, dominated by Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, is in agreement with the established epidemiology of urinary tract infection. Foxman described E. coli as the predominant uropathogen worldwide, while also recognizing the contribution of other gram-negative organisms in complicated urinary infections [18]. Flores-Mireles et al. similarly outlined the central pathogenic role of these organisms in both community-acquired and healthcare-associated UTIs [19]. The resistance pattern observed in the present study, particularly against commonly used fluoroquinolones and cephalosporins, also aligns with surveillance data reported by Linhares et al., who demonstrated increasing antimicrobial resistance among urinary isolates over time [20]. These findings highlight the growing challenge of empirical antibiotic selection and the need to adapt prophylactic and therapeutic regimens according to local antibiogram data. Another important implication of the present study is the clinical burden associated with postoperative infection. Patients who developed infection had longer hospital stay and greater treatment requirements, reflecting the substantial impact of infectious complications on patient recovery and resource utilization. This is consistent with the global PCNL data reported by de la Rosette et al., who showed that complications increase both morbidity and healthcare burden [22]. Omar et al. also emphasized that prevention, early recognition, and timely management of urosepsis are critical to limiting adverse outcomes after endourological procedures [21]. Taken together, the present findings support the need for careful preoperative risk stratification, stringent intraoperative asepsis, and judicious postoperative surveillance to reduce infectious morbidity after endourological surgery. Limitations The study was conducted at a single center with a relatively small cohort, which may limit generalizability. Advanced microbiological typing or molecular analysis of isolates was not performed, which could have helped in better characterizing pathogen sources.

Urinary infections remain an important complication following endourological procedures, particularly PCNL and TURP. Diabetes, prolonged surgery, and large calculi are major risk factors. Adherence to guidelines, individualized prophylaxis, and early identification of high-risk patients are key to reducing infection-related morbidity.

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