Urinary tract infections (UTIs) are among the most prevalent bacterial infections worldwide and represent a major public health concern. They affect approximately 150 million individuals annually, resulting in substantial morbidity, healthcare expenditure, and loss of productivity. UTIs occur when pathogenic microorganisms invade any part of the urinary tract, including the urethra, bladder, ureters, and kidneys. Women are disproportionately affected because of anatomical and physiological factors such as a shorter urethra and proximity of the urethral opening to the perianal region (1).

The etiology of UTIs is predominantly bacterial, with Gram-negative bacilli accounting for the majority of infections. Escherichia coli is responsible for nearly 70–90% of community-acquired UTIs, while other organisms such as Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and Enterococcus species contribute to a smaller proportion of cases (2). The spectrum of pathogens varies according to geographic location, healthcare setting, age, sex, and underlying medical conditions. Continuous surveillance of bacterial profiles is therefore necessary for guiding empirical antimicrobial therapy.

UTIs are generally classified as uncomplicated or complicated. Uncomplicated infections occur in otherwise healthy individuals without structural or functional abnormalities of the urinary tract. Complicated UTIs are associated with factors such as urinary obstruction, catheterization, diabetes mellitus, immunosuppression, and renal abnormalities (3). Recurrent infections may lead to chronic inflammation, renal scarring, and progressive deterioration of kidney function.

Renal function assessment plays an important role in patients with UTIs. Biomarkers such as serum creatinine, blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), and serum uric acid provide valuable information regarding kidney status. Acute pyelonephritis and recurrent UTIs can impair renal filtration capacity and may eventually contribute to chronic kidney disease (CKD) if left untreated (4). Elevated serum creatinine and BUN levels often indicate reduced renal clearance associated with infection-related renal damage.

The increasing prevalence of antimicrobial resistance among uropathogens further complicates treatment outcomes and may increase the risk of renal complications. Multidrug-resistant organisms can prolong infection duration, necessitate hospitalization, and contribute to recurrent episodes that adversely affect renal function (5).

Despite the clinical significance of UTIs, limited data are available regarding the relationship between bacteriological findings and renal function parameters in many healthcare settings. Understanding this relationship is important for early detection of renal impairment and implementation of appropriate therapeutic interventions.

Therefore, the present study was undertaken to determine the bacteriological profile of urinary tract infections and evaluate their impact on renal function parameters among patients attending a tertiary care hospital.

A hospital-based cross-sectional study was conducted in the Department of Microbiology in collaboration with the Department of Physiology, Department of Nephrology and General Medicine at a tertiary care teaching hospital over a period of six months. Study Population Patients presenting with symptoms suggestive of urinary tract infection, including dysuria, frequency, urgency, suprapubic pain, flank pain, and fever, were included in the study. Inclusion Criteria 1. Patients aged ≥18 years. 2. Patients clinically suspected of UTI. 3. Patients willing to provide informed consent. Exclusion Criteria 1. Patients on antibiotic therapy within the previous 72 hours. 2. Pregnant women. 3. Patients with known end-stage renal disease. 4. Patients unwilling to participate. Sample Size A total of 150 patients were enrolled consecutively during the study period. Sample Collection Clean-catch midstream urine samples were collected in sterile containers following standard procedures. Samples were transported immediately to the microbiology laboratory and processed within two hours of collection. Microbiological Analysis Urine samples were inoculated onto Cysteine Lactose Electrolyte Deficient (CLED) agar and MacConkey agar using a calibrated loop delivering 0.001 mL of urine. Plates were incubated aerobically at 37°C for 24 hours. Significant bacteriuria was defined as bacterial growth of ≥10⁵ colony-forming units (CFU)/mL. Isolates were identified based on colony morphology, Gram staining, and biochemical tests including indole, citrate utilization, urease, oxidase, and triple sugar iron tests. Renal Function Assessment Venous blood samples were collected for estimation of: • Serum creatinine (mg/dL) • Blood urea nitrogen (BUN) (mg/dL) • Estimated glomerular filtration rate (eGFR) (mL/min/1.73 m²) • Serum uric acid (mg/dL) Measurements were performed using automated biochemical analyzers according to manufacturer guidelines. Data Collection Demographic characteristics, clinical history, comorbidities, and laboratory findings were recorded using a structured proforma. Statistical Analysis Data were entered into Microsoft Excel and analyzed using SPSS version 25.0. Continuous variables were expressed as mean ± standard deviation, while categorical variables were expressed as frequencies and percentages. Student's t-test and Chi-square test were used for comparison. A p-value <0.05 was considered statistically significant. Ethical Considerations Institutional Ethics Committee approval was obtained before commencement of the study. Written informed consent was obtained from all participants.

Table 1. Distribution of Study Participants According to Age and Sex (n=150)

Females constituted the majority of study participants (65.3%). The highest proportion of patients belonged to the 31–45-year age group.

Table 2. Culture Results of Urine Samples

Among the 150 urine samples analyzed, 110 (73.3%) showed significant bacterial growth indicating urinary tract infection.

Table 3. Bacteriological Profile of Isolates (n=110)

Escherichia coli was the most common pathogen isolated, accounting for more than half of all culture-positive cases.

Table 4. Comparison of Renal Function Parameters

Culture-positive patients demonstrated significantly higher serum creatinine, BUN, and uric acid levels, while eGFR values were significantly lower compared with culture-negative patients.

The present study evaluated the bacteriological profile of urinary tract infections and their association with renal function parameters. Among 150 patients investigated, 73.3% demonstrated significant bacteriuria. Similar prevalence rates have been reported in previous studies where positive urine cultures ranged between 60% and 80% among symptomatic patients (6).

Females accounted for the majority of UTI cases in the current study. This observation is consistent with earlier investigations reporting a higher susceptibility among women due to anatomical characteristics, hormonal influences, and increased risk of ascending infection (7). The highest frequency of infection was observed among individuals aged 31–45 years, corresponding to the most active reproductive and occupational age group.

Escherichia coli was identified as the predominant pathogen, constituting 54.5% of all isolates. This finding agrees with reports from numerous epidemiological studies indicating that E. coli remains the principal uropathogen worldwide (8). The organism possesses several virulence factors, including adhesins, fimbriae, and biofilm-forming abilities that facilitate colonization of the urinary tract. Klebsiella pneumoniae was the second most common isolate, followed by Pseudomonas aeruginosa, Enterococcus faecalis, and Proteus mirabilis. Similar bacterial distributions have been documented in hospital-based studies across developing countries (9).

The present study also assessed the impact of bacteriologically confirmed UTIs on renal function. Patients with positive urine cultures exhibited significantly elevated serum creatinine and BUN levels compared with culture-negative patients. These findings suggest impaired renal filtration and possible inflammatory effects on renal tissues. Previous studies have demonstrated that recurrent or severe UTIs, particularly pyelonephritis, can contribute to transient or permanent renal dysfunction (10).

Furthermore, eGFR values were significantly reduced among culture-positive patients. Reduced eGFR reflects diminished glomerular filtration capacity and may indicate early renal involvement associated with infection. Similar observations have been reported by researchers investigating the relationship between chronic urinary infections and kidney impairment (11).

Serum uric acid levels were also significantly higher among infected patients. Elevated uric acid may result from reduced renal excretion secondary to impaired kidney function and inflammatory responses. This finding supports previous reports suggesting that systemic inflammation and renal dysfunction may coexist in patients with severe UTIs (12).

The results emphasize the importance of prompt diagnosis and treatment of UTIs. Delayed management may permit bacterial ascension to the upper urinary tract, increasing the risk of renal scarring and chronic kidney disease. Routine evaluation of renal function parameters in patients with recurrent or complicated UTIs may facilitate early detection of renal involvement and improve clinical outcomes.

Although the study provides valuable insights, limitations include the single-center design and relatively small sample size. Future multicenter studies incorporating antimicrobial susceptibility patterns and long-term renal outcomes would provide a more comprehensive understanding of the relationship between UTIs and kidney function.

Urinary tract infections remain a common bacterial disease, with Escherichia coli being the predominant causative organism. Significant alterations in renal function parameters, including elevated serum creatinine, BUN, uric acid levels, and reduced eGFR, were observed among culture-positive patients. These findings suggest that UTIs can adversely affect renal function, particularly when recurrent or inadequately treated. Early microbiological diagnosis, appropriate antimicrobial therapy, and routine monitoring of renal function are essential to prevent long-term renal complications.

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