Perspectives in Medical Research

INTRODUCTION

Urinary tract infections (UTIs) are among the most common bacterial infections affecting humans worldwide and constitute a major cause of morbidity in both community and hospital settings. They account for a significant proportion of outpatient visits and hospital admissions, resulting in considerable healthcare expenditure and antibiotic consumption^[1]. UTIs may affect individuals of all age groups and are particularly common in females, elderly patients, and those with underlying medical conditions^[2].

Clinically, UTIs range from uncomplicated infections involving the lower urinary tract to complicated infections affecting the upper urinary tract, often associated with structural abnormalities, catheterization, immunosuppression, or prolonged hospitalization^[3]. The burden of complicated UTIs is especially high in tertiary care hospitals, where patients frequently present with multiple comorbidities and prior exposure to broad-spectrum antimicrobials^[4].

Bacterial pathogens are the predominant etiological agents of UTIs. Escherichia coli remains the most frequently isolated uropathogen in both community-acquired and hospital-acquired infections^[5]. Other commonly reported organisms include Klebsiella species, Pseudomonas aeruginosa, Enterococcus species, Proteus species, and Staphylococcus species. The relative prevalence of these pathogens varies according to geographic location, patient population, and healthcare setting^[6].

Gram-negative bacilli account for the majority of UTI pathogens; however, Gram-positive cocci also play a significant role, particularly in hospitalized patients and those with indwelling urinary catheters^[7]. The emergence of antimicrobial resistance among uropathogens has further complicated the management of UTIs, emphasizing the need for continuous monitoring of local pathogen distribution and resistance trends^[8].

Tertiary care hospitals cater to a diverse patient population and often report a different microbial spectrum and higher resistance rates compared to primary and secondary care centers^[9]. Knowledge of the local prevalence and spectrum of urinary pathogens is therefore essential for guiding empirical therapy, optimizing antimicrobial stewardship programs, and improving patient outcomes^[10].

METHODOLOGY

This study was a descriptive cross-sectional study focusing on the laboratory identification of bacterial agents causing urinary tract infections. The work was undertaken in the Department of Microbiology, American International Institute of Medical Science College and Hospital, Udaipur. The study was conducted over a period of three months.

Study Subjects

Urine samples obtained from a total of 110 patients attending both outpatient and inpatient services, irrespective of age or gender, and clinically suspected to have urinary tract infection were included in the study.

Inclusion criteria

• Patients with clinical symptoms suggestive of UTI such as dysuria, increased frequency of micturition, urgency, suprapubic pain, fever, or flank pain.

• Patients who had not received antibiotics.

Exclusion criteria

• Samples that were inadequately collected or improperly labeled

• Specimens received after prolonged delay without refrigeration

Collection and Handling of Samples

Midstream urine samples were collected in sterile, leak-proof containers. In catheterized patients, urine was aspirated aseptically from the catheter sampling port. All specimens were transported immediately to the laboratory and processed within two hours. Samples were stored at 4°C if processing was delayed.

Microscopic Examination

Uncentrifuged urine samples were examined under the microscope using wet mount preparations to identify pus cells, red blood cells, epithelial cells, and bacteria. These findings were later correlated with culture results.

Bacteriological Culture

After gentle mixing, urine specimens were inoculated using a calibrated inoculating loop delivering 0.001 mL onto the Cysteine Lactose Electrolyte Deficient (CLED) agar, MacConkey agar, blood agar and nutrient agar. The inoculated plates were incubated aerobically at 37°C and examined after 18–24 hours. Blood agar plates were specifically observed for haemolytic reactions. Culture plates showing no growth were incubated for an additional 24 hours before being reported as negative.

Assessment of Significant Bacteriuria

The number of colonies obtained was multiplied by the loop factor to calculate bacterial count per millilitre. A colony count of ≥10⁵ CFU/mL was considered indicative of significant bacteriuria, as described by Kass, while lower counts were evaluated in relation to clinical symptoms and microscopy findings.

Identification of Isolates

Bacterial growth was identified through observation of colony characteristics on different culture media. Gram staining was done to determine cellular morphology and Gram reaction. Standard biochemical tests including catalase, oxidase, indole, citrate utilization, urease, triple sugar iron (TSI) agar reactions, and motility testing were performed. Identification was finalized using conventional microbiological criteria.

Quality Assurance

All culture media and reagents were prepared and tested according to standard protocols. Quality control strains were used to verify the performance of media and biochemical tests. Strict aseptic techniques were maintained throughout the study.

Data Recording and Analysis

Laboratory findings were entered into a structured proforma and later transferred to a spreadsheet for analysis. Data were summarized using descriptive statistics and presented as percentages.

Ethical Approval

Prior approval for the study was obtained from the Institutional Ethics Committee. Confidentiality of patient information was maintained, and samples were processed exclusively for research and diagnostic purposes.

RESULTS

A total of 110 bacterial isolates were recovered from urine specimens [Table. 1]. Escherichia coli was the most predominant uropathogen, accounting for 45 isolates (41%), followed by coagulase-negative staphylococci (CONS) with 23 isolates (21%). Klebsiella spp. constituted 19 isolates (17%), while Enterococcus spp. accounted for 10 isolates (9%). Pseudomonas spp. was isolated in 7 cases (6%). Less frequently isolated organisms included Acinetobacter spp. (3 isolates; 3%), Staphylococcus spp. (2 isolates; 2%), and Proteus vulgaris (1 isolate; 1%). Overall, Gram-negative bacteria predominated among the isolates, highlighting E. coli as the leading cause of urinary tract infections in the study population.

The gender-wise distribution of bacterial isolates from urine specimens among inpatient (IPD) and outpatient (OPD) populations is shown in [Table. 2]. Among IPD samples, a higher number of isolates were obtained from male patients (55 isolates) compared to female patients (26 isolates). In the OPD group, isolates were also more frequent in males (16 isolates) than females (13 isolates). Escherichia coli was the most commonly isolated organism in both IPD and OPD samples, with a predominance in males (IPD: 22 males vs. 11 females; OPD: 8 males vs. 4 females). 

Table 1: Distribution of Bacterial Isolates from Urine Specimens

Klebsiella spp. were the second most frequent isolates, mainly recovered from male IPD patients (13 isolates), with fewer isolates from females and OPD patients. Pseudomonas spp. was predominantly isolated from male IPD patients (5 isolates), with minimal representation in OPD samples. Overall, the results indicate a higher prevalence of urinary tract infections among male patients, particularly in the inpatient setting, with E. coli remaining the predominant uropathogen across both genders and clinical settings.
 

Table 2: Gender-wise Distribution of bacterial isolates from the Urine Specimens

The IPD–OPD wise distribution of urinary isolates is shown in [Table. 3]. Among IPD isolates, Gram-negative bacilli (GNB) predominated, accounting for 58 isolates, while Gram-positive cocci (GPC) constituted 23 isolates. Similarly, in OPD samples, GNB were more frequently isolated (17 isolates) compared to GPC (12 isolates). Overall, Gram-negative bacilli were the predominant pathogens in both IPD and OPD urine specimens, with a higher overall isolation rate observed in the inpatient setting compared to the outpatient setting.

Table 3: IPD–OPD wise Distribution of Gram - negative bacilli and Gram - positive cocci 

DISCUSSION

This study investigated the spectrum and prevalence of urinary pathogens isolated from urine specimens at a tertiary care hospital, demonstrating several important epidemiological patterns when compared with similar studies both internationally and within India.

In our findings, Escherichia coli was the most predominant uropathogen, accounting for 41% of isolates, followed by coagulase-negative staphylococci (21%) and Klebsiella spp. (17%). This pattern parallels epidemiological data from large tertiary care settings, where E. coli consistently emerges as the most frequent pathogen in UTI cases due to its virulence factors and adaptability within the urinary tract^[1]. A retrospective tertiary care study from North West India also reported E. coli as the leading isolate (45.7%), followed by coagulase-negative staphylococci and Klebsiella spp., underscoring the consistency of E. coli predominance in Indian hospital settings^[11].

The high rate of Gram-negative bacilli in our study is consistent with broader global and regional observations. Another multicentric Indian epidemiological analysis reported that E. coli and Klebsiella pneumoniae collectively accounted for a large majority of community UTI cases, reflecting the prominence of Enterobacteriaceae in urinary infections^[12]. This supports the conclusion that Gram-negative organisms dominate the uropathogen profile in both community and hospital environments.

Compared to some international data where Gram-positive and non-fermenters occasionally contribute more substantially to the uropathogen load, the Indian data maintains a higher relative proportion of E. coli and Klebsiella spp., which may relate to differences in patient demographics, antibiotic exposure, and healthcare practices^[12, 13].

Gender-wise distribution in our study showed a higher number of male inpatient isolates, this finding may be attributed to increased catheterization, prolonged hospitalization, and underlying comorbidities among male patients. Whereas many Indian community studies report higher UTI prevalence in females, particularly in outpatient community settings.¹⁴ This discrepancy likely reflects the tertiary care population, where males with comorbid conditions or catheterization may be over-represented. In contrast, community-based studies often find a female predominance because of anatomical predisposition and hygiene practices leading to higher UTI susceptibility^[15].

The isolation of Pseudomonas spp., although less frequent in our study, is clinically important given its association with nosocomial and complicated UTIs. Similar low but significant rates of Pseudomonas have been documented in other Indian tertiary studies, emphasizing the need for careful surveillance due to its intrinsic and acquired resistance mechanisms^[16].

Our findings reinforce the need for periodic local surveillance of uropathogen prevalence and antimicrobial sensitivity because of evolving patterns of resistance and pathogen distribution. This is especially relevant in tertiary hospitals, where empirical therapy must be guided by updated local data to enhance clinical outcomes and reduce the emergence of resistant strains.

CONCLUSION

This study demonstrates that urinary tract infections in a tertiary care hospital are predominantly caused by Gram-negative bacteria, with Escherichia coli being the most common uropathogen. A higher number of isolates were obtained from inpatients, reflecting the impact of hospitalization and associated risk factors. The presence of both Gram-negative and Gram-positive organisms highlights the diverse etiological profile of UTIs in tertiary care settings. Regular surveillance of local uropathogen patterns is essential to support appropriate empirical therapy and strengthen antimicrobial stewardship efforts.

DISCLOSURE

Funding: Nil.

Conflict of Interest: None.