European Journal of Cardiovascular Medicine

Urinary tract infections (UTIs) are among the most common bacterial infections globally, affecting people across all age groups and accounting for a significant proportion of outpatient and inpatient antibiotic prescriptions (Flores-Mireles et al., 2015). Women are particularly susceptible, with nearly 50% expected to experience at least one UTI in their lifetime, often with recurrent episodes (Foxman, 2014). UTIs can present as uncomplicated cystitis or progress to severe complications such as pyelonephritis and urosepsis, especially when caused by drug-resistant pathogens.

One of the most alarming trends in recent years is the increasing incidence of UTIs caused by extended-spectrum beta-lactamase (ESBL)-producing organisms. ESBLs are enzymes that confer resistance to most beta-lactam antibiotics, including penicillins, cephalosporins, and monobactams, thus severely limiting the effectiveness of these commonly used treatments (Paterson & Bonomo, 2005). The spread of ESBL-producing bacteria has become a major public health concern, particularly in hospital settings and among patients with recurrent or complicated UTIs (Rodríguez-Baño et al., 2018). Among ESBL-producing pathogens, Escherichia coli and Klebsiella pneumoniae are the leading uropathogens implicated in both community-acquired and healthcare-associated UTIs (Peirano & Pitout, 2019). The resistance exhibited by these organisms is not limited to beta-lactams; many also display multidrug resistance to commonly used antibiotics such as fluoroquinolones and trimethoprim-sulfamethoxazole, further complicating empirical therapy (Doi et al., 2017). Carbapenems are often considered the last-resort treatment for infections caused by ESBL producers, but overuse of these agents contributes to the global rise in carbapenem-resistant Enterobacteriaceae (CRE) (van Duin & Doi, 2017).

The resistance patterns of ESBL-producing uropathogens can vary significantly across geographical locations, healthcare institutions, and patient populations, underscoring the importance of local surveillance data in guiding empirical antibiotic selection (Pitout & Laupland, 2008). Timely initiation of effective antimicrobial therapy is crucial, as delays in appropriate treatment have been associated with poor clinical outcomes, including increased rates of hospitalization, complications, and mortality (Tamma et al., 2014).

Given these concerns, the present study was conducted to evaluate the effectiveness of selective antibiotics against ESBL-producing E. coli and Klebsiella pneumoniae isolated from urine samples at Sarvodaya Hospital and Research Center, Sector Faridabad. By assessing the local antimicrobial susceptibility patterns over a two-month period, this research aims to provide actionable data to inform empirical treatment strategies, improve patient outcomes, and support institutional antimicrobial stewardship efforts.

This prospective observational study was conducted over a period of two months, from February to March 2025, in the Department of Microbiology at Sarvodaya Hospital and Research Center, Sector Faridabad. The study aimed to evaluate the effectiveness of selective antibiotics in treating urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae.

Urine samples were collected from patients of both genders and all age groups who presented with clinical symptoms suggestive of UTIs and were referred for routine microbiological evaluation. Midstream clean-catch urine samples were obtained under sterile conditions and immediately transported to the microbiology laboratory for processing.

Upon receipt, the samples were subjected to standard microbiological procedures, including culture on cystine-lactose-electrolyte-deficient (CLED) agar. The plates were incubated aerobically at 37°C for 18-24 hours. Significant bacteriuria was confirmed based on colony counts, and the isolates were identified to the species level using routine biochemical tests and automated identification through the VITEK 2 Compact system (bioMérieux, France).

Antibiotic susceptibility testing (AST) was performed using the VITEK 2 Compact system according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. ESBL production was confirmed by the VITEK 2 system based on automated detection algorithms. For E. coli, the antibiotics tested included: amikacin, amoxicillin-clavulanic acid, cefepime, ceftriaxone, cefuroxime, ciprofloxacin, ertapenem, fosfomycin, imipenem, meropenem, nitrofurantoin, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, and gentamicin. For Klebsiella pneumoniae, the antibiotics tested were: amikacin, amoxicillin-clavulanic acid, cefepime, ceftriaxone, cefuroxime, ciprofloxacin, ertapenem, imipenem, meropenem, nitrofurantoin, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, and gentamicin. Fosfomycin susceptibility was not evaluated for Klebsiella pneumoniae.

Isolates were categorized as sensitive or resistant based on minimum inhibitory concentration (MIC) breakpoints recommended by the CLSI. All quality control procedures were strictly followed throughout the study using appropriate control strains. Data on patient demographics, isolate distribution by gender, and month of isolation were recorded and analyzed.

The results were compiled and statistically evaluated to determine the sensitivity and resistance patterns of the antibiotics tested against the isolated ESBL-producing uropathogens. The study strictly adhered to ethical standards, and patient confidentiality was maintained at all stages.

During the two-month study period, a total of 186 ESBL-producing isolates were obtained from urine samples of patients with suspected urinary tract infections at Sarvodaya Hospital and Research Center, Faridabad. The distribution of these isolates by organism and gender is presented in Table 1. Subsequent, tables illustrate the antibiotic susceptibility profiles of the isolated organisms and provide a comparative analysis of the effectiveness of various antibiotics tested.

Table 1: Distribution of ESBL-Positive Isolates by Organism and Gender

Table 1 shows the consolidated distribution of ESBL-positive Escherichia coli and Klebsiella pneumoniae isolates collected from urine samples over the two-month study period. Among the 170 E. coli isolates, 70 were from male patients and 100 from female patients. For Klebsiella pneumoniae, 4 isolates were from male patients and 12 from female patients. Overall, ESBL-producing E. coli accounted for 91.4% of the total isolates, indicating its predominance in urinary tract infections during the study period.

Table 2: Antibiotic Susceptibility Pattern of ESBL-Producing E. coli

Table 2 presents the antibiotic susceptibility profile of ESBL-producing E. coli. High sensitivity was observed for amikacin (91.67%), meropenem (90.00%), imipenem (87.50%), piperacillin-tazobactam (85.00%), nitrofurantoin (83.33%), and ertapenem (83.33%). Moderate sensitivity was seen with gentamicin (75.00%) and fosfomycin (79.17%). In contrast, high resistance was noted to ciprofloxacin (91.67%), ceftriaxone (87.50%), cefuroxime (83.33%), and amoxicillin-clavulanic acid (75.00%), indicating limited effectiveness of these commonly used antibiotics.

Table 3: Antibiotic Susceptibility Pattern of ESBL-Producing Klebsiella pneumoniae

Table 3 summarizes the susceptibility patterns of ESBL-producing Klebsiella pneumoniae. The isolates showed the highest sensitivity to imipenem (93.33%), ertapenem (86.67%), meropenem (86.67%), piperacillin-tazobactam (80.00%), and amikacin (80.00%). Moderate sensitivity was observed with gentamicin (73.33%) and nitrofurantoin (60.00%). The isolates exhibited significant resistance to ciprofloxacin (93.33%), ceftriaxone (86.67%), cefuroxime (86.67%), and amoxicillin-clavulanic acid (80.00%). These findings support the preferential use of carbapenems and amikacin for treatment.

Table 4: Comparative Sensitivity of Key Antibiotics Against ESBL-Producing E. coli and Klebsiella pneumoniae

Table 4 provides a comparative analysis of key antibiotics against ESBL-producing E. coli and Klebsiella pneumoniae. Both organisms demonstrated high sensitivity to carbapenems (imipenem: 87.50% in E. coli, 93.33% in Klebsiella pneumoniae; meropenem: 90.00% and 86.67%, respectively). Amikacin showed excellent sensitivity in both groups (91.67% in E. coli and 80.00% in Klebsiella pneumoniae). Significant resistance to ciprofloxacin and amoxicillin-clavulanic acid was common to both organisms, with ciprofloxacin sensitivity rates as low as 8.33% for E. coli and 6.67% for Klebsiella pneumoniae. These findings underline the critical need for targeted therapy based on local susceptibility patterns.

The present study provides a critical evaluation of the effectiveness of selective antibiotics in treating urinary tract infections (UTIs) caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae. The high prevalence of ESBL-producing E. coli (91.4% of total isolates) compared to Klebsiella pneumoniae (8.6%) aligns with findings from similar studies, which have consistently reported E. coli as the most common etiological agent of UTIs globally (Gupta et al., 2011; Pitout & Laupland, 2008).

Our results demonstrated that carbapenems (imipenem, meropenem, and ertapenem) remain the most effective antibiotics against both pathogens, with sensitivities exceeding 86% in E. coli and Klebsiella pneumoniae. These findings reinforce the established role of carbapenems as the gold standard for treating ESBL-producing organisms (Paterson & Bonomo, 2005; Rodríguez-Baño et al., 2004). However, the emerging concern of carbapenem resistance worldwide emphasizes the importance of antimicrobial stewardship to preserve their efficacy (Nordmann et al., 2012). Amikacin also demonstrated high sensitivity rates (91.67% for E. coli and 80.00% for Klebsiella pneumoniae), suggesting it as a potent alternative, especially in cases where carbapenem-sparing regimens are considered. Nitrofurantoin showed promising results against E. coli (83.33% sensitivity), consistent with its continued recommendation for the empirical treatment of lower UTIs (Huttner et al., 2015). However, its reduced sensitivity against Klebsiella pneumoniae (60.00%) limits its utility for this pathogen. Fosfomycin displayed substantial activity against E. coli (79.17% sensitivity), which supports its re-emerging role as an effective oral agent for uncomplicated UTIs caused by multidrug-resistant pathogens (Falagas et al., 2010). Unfortunately, fosfomycin susceptibility was not tested against Klebsiella pneumoniae in this study, which may be an area for future research. Alarmingly, high resistance was observed against commonly used antibiotics such as ciprofloxacin and amoxicillin-clavulanic acid. Ciprofloxacin exhibited extremely low sensitivity rates in both E. coli (8.33%) and Klebsiella pneumoniae (6.67%), making it unsuitable for empirical therapy in this setting. These findings are in line with growing global resistance to fluoroquinolones among ESBL-producing Enterobacteriaceae (Schito et al., 2009). The significant resistance to amoxicillin-clavulanic acid (75.00% in E. coli and 80.00% in Klebsiella pneumoniae) also highlights its limited effectiveness against ESBL producers, consistent with prior reports (Rodríguez-Baño et al., 2004).

Additionally, piperacillin-tazobactam demonstrated good activity (85.00% sensitivity for E. coli and 80.00% for Klebsiella pneumoniae), suggesting its potential as an alternative to carbapenems in appropriate clinical scenarios. Recent studies suggest that piperacillin-tazobactam could be used safely in some non-severe ESBL infections (Harris et al., 2018), but local susceptibility patterns must always guide its use.

The higher prevalence of isolates from female patients, particularly for E. coli, is expected as UTIs are generally more common in women due to anatomical and physiological factors (Foxman, 2010). However, a notable number of male patients were also affected, underlining the importance of considering resistant organisms in all patient groups.

Study Limitations

One limitation of this study is the relatively short duration (two months), which may not fully capture seasonal variations in bacterial prevalence or resistance patterns. Additionally, molecular characterization of ESBL genes was not performed, which could have provided further insights into the resistance mechanisms.

Implications

The findings underscore the critical need for continuous local surveillance, targeted antibiotic therapy, and stringent antimicrobial stewardship programs. Empirical therapy for UTIs in this region should prioritize carbapenems, amikacin, and, where appropriate, nitrofurantoin and piperacillin-tazobactam, while avoiding fluoroquinolones and amoxicillin-clavulanic acid unless supported by susceptibility data.

Carbapenems, amikacin, nitrofurantoin, and piperacillin-tazobactam demonstrated the highest effectiveness against ESBL-producing E. coli and Klebsiella pneumoniae in this study. Ciprofloxacin and amoxicillin-clavulanic acid exhibited high resistance rates, making them less suitable for empirical therapy in this setting. This study highlights the importance of continuous local surveillance to guide effective antibiotic stewardship.

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