Bacterial profile and antibiotic resistance pattern of uropathogens isolated from patients with complicated urinary tract infections in a tertiary care hospital in Dhaka, Bangladesh

Abstract

Introduction

In Bangladesh, the antibiotic resistance patterns of uropathogens in patients with complicated urinary tract infections (cUTIs) remain poorly understood. This study aimed to identify the most prevalent bacteria in urine samples from cUTI patients and assess their resistance to commonly used antibiotics.

Method

Between January 2023 and June 2024, we conducted this retrospective cross-sectional study among patients from the Nephrology department of Bangladesh Medical College Hospital, Dhaka. Clinical and microbiological data were retrieved for adult patients with culture-confirmed UTI (≥ 10⁵ CFU/mL). Reports from patients with at least one documented complicating factor were included in the analysis. The antibiotic susceptibility of 31 commonly used antibiotics was evaluated using the standard Kirby-Bauer method. Descriptive statistics were used to summarize bacterial isolates, patient demographics, complicating factors, and antibiotic sensitivity patterns. Inferential tests were performed to assess associations between risk factors and specific pathogens.

Results

A total of 170 urine culture-positive samples from eligible patients were included in this study. E. coli was the most prevalent pathogen (49%) observed, followed by K. pneumoniae (25%) and P. aeruginosa (10%). Female patients accounted for 65% of cases. Diabetes mellitus (66%) was the most prevalent complicating factor, along with the presence of renal stone (16%) and an indwelling urinary catheter (11%). P. aeruginosa was significantly more common in diabetic and transplant patients. Antibiotic susceptibility testing revealed high resistance among E. coli and K. pneumoniae to Quinolones (10–55%) and Cephalosporins (4–55%). In contrast, P. aeruginosa showed significant resistance to aminoglycosides (31–63%) and Carbapenems (0–38%).

Conclusion

This study demonstrates that E. coli and K. pneumoniae are the predominant uropathogens in patients with cUTIs in Bangladesh. Both organisms exhibited notable resistance to Quinolones and the Cephalosporins group of antibiotics. These findings underscore the need for tailored antibiotic stewardship programs to guide appropriate treatment decisions and improve clinical outcomes in cUTI patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-025-11941-z.

Background

Globally, urinary tract infections (UTIs) are among the most common bacterial infections. Recent estimates suggest that approximately 400 million people are affected by UTIs annually [1, 2]. While UTIs can occur in both men and women, females are more frequently affected, primarily due to anatomical differences that increase their susceptibility [3–6]. Furthermore, the risk of infection also rises with age and in individuals with certain underlying health conditions [7]. In addition to their clinical impact, UTIs pose a major public health challenge worldwide due to their association with considerable morbidity, mortality, and healthcare costs. In 2019 alone, approximately 236,790 deaths and over 520,000 disability-adjusted life years were attributed to UTIs [8]. The financial burden of UTI is also substantial, with global healthcare expenditures related to this condition estimated at over $6 billion per year [9, 10].

UTIs are classified as complicated (cUTI) if they occur in individuals with underlying comorbidities, have structural or functional urinary tract abnormalities, or have factors that facilitate bacterial colonization and reduce treatment effectiveness [11]. A recent systematic review estimated that complicated urinary tract infections (cUTIs) comprise approximately 17.6% to 50.9% of all UTI cases, highlighting the considerable clinical burden associated with this subgroup [12]. cUTIs can lead to severe health consequences, including septic shock, kidney failure, or death [13]. It is estimated that worldwide, UTIs account for 10–15% of hospitalizations for all infectious causes, with most admissions attributed to cUTIs [14].

Common bacterial pathogens responsible for UTIs are Escherichia coli (E. coli), Klebsiella sp., Proteus sp., Staphylococcus sp., Enterococcus sp., Pseudomonas aeruginosa (P. aeruginosa), and Enterobacter sp. However, their prevalence varies across populations and regions [15–19]. As a result, UTIs are often treated empirically with broad-spectrum antibiotics instead of targeted antibiotic therapy based on laboratory evaluation [20]. This contributes to the emergence of resistant organisms, making antimicrobial resistance (AMR) among bacterial uropathogens an escalating global health concern. The situation is further exacerbated by factors such as antibiotic misuse, self-medication, inappropriate dosing, and prolonged or inadequate treatment duration [21–24]. For patients with cUTIs, rising AMR complicates treatment due to frequent hospitalizations [25] and immunosuppression, increasing the risk of multidrug-resistant infections. A primary concern in managing cUTIs is the rising resistance to commonly prescribed first-line antibiotics, including third-generation Cephalosporins, Fluoroquinolones, and Trimethoprim-sulfamethoxazole [26–28]. Due to the high prevalence of cUTI diagnoses and AMR, Carbapenems are increasingly being used as first-line treatment [29]. While this approach aims to ensure patients receive effective initial therapy, it also contributes to greater selection pressure, further driving AMR.

In Bangladesh, the prevalence of UTI ranges from 8.9% to 42% among different patient groups [3, 18, 30, 31]. On the other hand, the prevalence of cUTIs has been reported to range from 20% to 66% in the country, reflecting their significant contribution to the burden of urinary infections in local healthcare settings [32, 33]. Studies have shown that over 70% of bacterial uropathogens detected in Bangladeshi patients are multidrug-resistant [34, 35]. The most common uropathogens, E. coli and Klebsiella pneumoniae (K. pneumoniae), exhibit high resistance to commonly used antibiotics [36]. Previous studies on cUTIs conducted in Bangladesh have also identified E. coli and K. pneumoniae as the predominant uropathogens [33, 37]. For these organisms, resistance rates for cefuroxime and ceftazidime were reported at 64.71% and 46.85% for E. coli and 46.85% for both antibiotics in Klebsiella sp [35]. However, limited data on the specific AMR patterns for cUTI patients are available in the context of Bangladesh. The lack of comprehensive AMR surveillance and hospital-based data, particularly for cUTI patients, makes it further challenging to assess the burden accurately in these settings.

Thus, we conducted this study to assess the prevalence of bacteriuria and antibiotic susceptibility patterns among patients with cUTIs seeking care at a tertiary medical college hospital in Dhaka, Bangladesh. The findings could help guide more effective treatment strategies and inform public health policies aimed at combating antibiotic resistance in cUTI management, particularly in low- and middle-income countries (LMICs).

Materials and methods

Study design, participants, and data source

We conducted this retrospective cross-sectional study in the Nephrology Outpatient Department at Bangladesh Medical College Hospital, Dhaka. From January 2023 to June 2024, laboratory data on urine culture and antibiotic susceptibility testing (AST) were retrieved from the Microbiology department’s database. Corresponding clinical data, including demographic information (age, sex) and medical history, were then obtained by reviewing patients’ electronic and paper-based records available in the Nephrology Department.

Inclusion and exclusion criteria

For this analysis, we included reports from adult patients (aged ≥ 18 years) who had attended the nephrology outpatient department during the study period and provided urine samples to be tested for culture and AST. UTI was defined by positive urine cultures (≥ 10⁵ colony-forming units [CFU]/mL for clean-catch midstream urine or ≥ 10⁴ CFU/mL for catheterized urine) [38, 39]. Following laboratory confirmation of UTI, we reviewed corresponding clinical records to identify patients with at least one complicating factor(s) (e.g., urinary catheterization, structural or functional abnormalities, immunosuppression, pregnancy, kidney diseases, etc.). A patient with UTI and the presence of a complicating factor was then considered a case of cUTI and included in the study [40]. Any patients with missing or incomplete medical or microbiological records, and the absence of complicating factors, were excluded from the study.

Laboratory procedures

Urine culture

To carry out the urine culture test, midstream clean-catch urine samples were obtained from non-catheterized patients, while urine samples from catheterized patients were collected via aseptic aspiration from the catheter port. Per hospital protocols, samples were collected before initiating antibiotic therapy and transported to the Microbiology Laboratory within two hours or stored at 4 °C if delayed. A bacterial colony count of ≥ 10⁵ colony-forming units (CFU)/mL for clean-catch midstream urine or ≥ 10⁴ CFU/mL for catheter-derived samples was considered diagnostic for a UTI.

Antibiotic susceptibility testing (AST)

Antibiotic susceptibility testing for all isolated organisms was conducted using the Kirby-Bauer disc diffusion method against 31 commonly used antibiotics. Testing and interpretation followed the Clinical and Laboratory Standards Institute (CLSI) 2021 guidelines [41].

A bacterial suspension was prepared from a pure colony of each isolate using 0.85% sterile normal saline and adjusted to match the turbidity of a 0.5 McFarland standard. Using a sterile cotton swab, the suspension was uniformly inoculated onto sterile Mueller-Hinton agar plates (pH 7.2–7.4). After inoculation, antibiotic discs were placed on the agar surface, maintaining a minimum distance of 15 mm from the plate edge and 24 mm between disc centers to avoid overlapping zones.

Plates were allowed to stand at room temperature for 15 min to enable pre-diffusion and then incubated at 37 °C for 24 h. Following incubation, the diameter of the zone of inhibition around each disc was measured to the nearest millimetre using a metal calliper. Based on CLSI breakpoints, the results were interpreted as susceptible (S), intermediate (I), or resistant (R).

Data analysis

We used descriptive statistics to summarize the bacterial isolates, participants’ demographic characteristics, and complicating factors. The participants in this study were grouped by age (18–35, 35–50, 50–65, and > 65 years) to analyze organism distribution. The antibiotics were grouped according to their therapeutic class. The overall resistance and sensitivity rates for the most common uropathogens in this study to routinely tested first-line antibiotics were determined by calculating the percentage of bacterial isolates that exhibited resistance or sensitivity to each antibiotic agent out of the total number of isolates tested for that specific agent. Frequency and percentages were used to describe the distribution of uropathogens, antibiotic resistance patterns, and susceptibility over the study period in the tables. To explore associations between patient characteristics and specific pathogens, we assessed the distribution of organisms by the available demographic variables (age and sex) and by complicating factors. Chi-square or Fisher’s exact tests were applied as appropriate to determine statistically significant differences. A p-value of < 0.05 was considered statistically significant. All analyses were conducted with Stata 15.0 software (StataCorp. 2015. Stata Statistical Software: Release 15. College Station, TX: StataCorp LP).

Ethical consideration

Ethical approval for this retrospective study was obtained from the Center for Health Innovation, Research, Action, and Learning – Bangladesh (CHIRAL Bangladesh). As the study involved the secondary use of medical records without direct contact with patients and posed no risk of harm, the requirement for informed consent was waived by the ethics committee. All personal identifiers were removed, and data were handled with strict confidentiality to protect participants’ privacy in accordance with the ethical principles outlined in the Declaration of Helsinki.

Results

Distribution of cUTI-causing uropathogens

In this study, data from 170 urine samples collected from patients with cUTIs were analyzed. Among the identified pathogens, E. coli was the most common, found in 49% of cases, followed by K. pneumoniae (25%) and P. aeruginosa (10%). Less frequent isolates included Enterococcus faecalis, Acinetobacter baumannii (A. baumannii), Staphylococcus aureus (S. aureus), and Streptococcus agalactiae (S. agalactiae) (Table 1).

Table 1.

Distribution of cUTI-causing bacteria (N = 170)

Bacterial isolates	n (%)
Acinetobacter baumannii	5(3)
Escherichia coli	83(49)
Klebsiella pneumoniae	42(25)
Pseudomonas aeruginosa	16(10)
Enterococcus faecalis	14(8)
Staphylococcus aureus	4(2)
Streptococcus agalactiae	4(2)
Proteus mirabilis	2(1)
Total	170(100)

Distribution of cUTI-causing uropathogens based on age and gender

The majority (65%) of the bacterial isolates were obtained from female patients. Among the uropathogens, E. coli was most commonly found among women, while P. aeruginosa and A. baumannii were more frequently observed in male patients. Notably, the predominance of P. aeruginosa among males was statistically significant, with 81% of cases occurring in men compared to 19% in women (p < 0.001). In the age-group distribution, E. coli was most prevalent in the 50–65 age group, while P. aeruginosa and K. pneumoniae isolates were found in higher frequencies among younger adults (Table 2). Enterococcus faecalis exhibited a significant age-related distribution, being most common among patients aged 50–65 years (p = 0.037). However, E. coli and K. pneumoniae, the two most frequently isolated pathogens, did not exhibit any statistically significant differences by sex or age.

Table 2.

The distribution of cUTI-causing pathogens by gender and age groups of patients (N = 170)

Organism	Sex			Age Groups
	Male n (%)	Female n (%)	p-value	18–35 years n (%)	35–50 years n (%)	50–65 years n (%)	> 65 years n (%)	p-value
Acinetobacter baumannii	4(80)	1(20)	0.050	2(40)	2(40)	1(20)	0	0.161
Escherichia coli	24(29)	59(71)	0.121	6(7.23)	23(27.71)	30(36.14)	24(28.92)	0.055
Klebsiella pneumoniae	13(31)	29(69)	0.556	6(14.29)	14(33.33)	14(33.33)	8(19.05)	0.088
Pseudomonas aeruginosa	13(81)	3(19)	< 0.001	4(25)	9(56.25)	0	3(18.75)	0.001
Enterococcus faecalis	2(14)	12(86)	0.094	0	3(21.43)	10(71.43)	1(7.14)	0.037
Staphylococcus aureus	2(50)	2(50)	0.610	1(25)	2(50)	1(25)	0	0.490
Streptococcus agalactiae	0(0)	4(100)	0.299	1(25)	0	3(75)	0	0.159
Proteus mirabilis	1(50)	1(50)	0.098	0	0	1(50)	1(50)	0.779
Total (170)	59(35)	111(65)		20(11.76)	53(31.18)	60(35.29)	37(21.76)

Distribution of cUTI patients based on the type of complicating factors

Among the complicating factors observed in cUTI patients in this study, diabetes mellitus (DM) was the most prevalent, affecting 66% of patients, underscoring its role as a significant risk factor (Table 3). Glomerulonephritis was present in 13% of the participants, and an indwelling urinary catheter was seen in 11% of patients. Chronic kidney disease (CKD) was present in 9% of cases, highlighting the possible link between renal impairment and increased UTI susceptibility. Other conditions contributing to inefficient bladder emptying and bacterial overgrowth included renal stones (16%), renal allograft recipients (17%), glomerulonephritis (13%), neurogenic bladder (5%), and urethral stricture (2%). Additionally, pregnancy (5%) and breast cancer patients undergoing chemotherapy (4%) among females, as well as benign prostatic hyperplasia (4%) in males, were seen among the participants.

Table 3.

Types of complicating factors presented in patients with cUTI (N = 170)

Category	Complicating Factors	n (%)
Host-related factors/Immunosuppressive condition	Diabetes Mellitus	113 (66)
	Systemic Lupus Erythematosus	3(2)
	Rheumatoid Arthritis	2(1)
	Breast carcinoma on Chemotherapy	6(4)
	Renal Allograft Recipient	28(17)
Structural/Functional Abnormalities of the urinary tract	Benign Enlargement of the Prostate	6(4)
	Neurogenic Bladder	9(5)
	Stricture Urethra	2(2)
	Renal Stone	27(16)
Device-related condition	Indwelling urinary catheter	18(11)
Obstetric condition	Pregnancy	8(5)
Renal Diseases	Chronic Kidney Disease	17(9)
	Glomerulonephritis	23(13)
	Lupus Nephritis	1(1)

*Percentage can be more than 100% as multiple complicating factors could be recorded in an individual

Distribution of cUTI-causing pathogens by complicating factors in patients with cUTI

E. coli remained the dominant pathogen across most complicating conditions, while P. aeruginosa and A. baumannii were notably associated with immunosuppressive states. Patients with renal stones, an indwelling urinary catheter, and CKD showed a predominance of E. coli, but without significant associations. On the other hand, renal allograft recipients had a statistically significant association with both E. coli and P. aeruginosa. patients with breast cancer on an active treatment regimen showed significant associations with A. baumannii (p < 0.01) (Table 4).

Table 4.

Distribution of cUTI-causing pathogen by complicating factors in patients with cUTI (N = 170)

Complicating Factors	Acinetobacter baumanii, n (%)	E. coli, n (%)	K. pneumoniae, n (%)	P. aeruginosa, n (%)	Entero-coccus faecalis, n (%)	Staphylo-coccus aureus, n (%)	Strepto-coccus agalactiae, n (%)	Proteus mirabilis, n (%)
Diabetes Mellitus (n = 113)	3 (3)	57 (51)	28 (25)	6 (5)**	12 (10)	2 (2)	4 (3)	1 (1)
Systemic Lupus Erythematosus (n = 3)	-	1 (33)	2 (67)	-	-	-	-	-
Rheumatoid Arthritis (n = 2)	-	2 (100)	-	-	-	-	-	-
Breast carcinoma on Chemotherapy (n = 6)	2 (33)**	4 (67)	-	-	-	-	-	-
Renal Allograft Recipient (n = 28)	2 (7)	8 (29)*	8 (29)	9 (32)***	1 (3)
Benign Enlargement of the Prostate (n = 6)	-	3 (50)	2 (33)	1 (17)	-	-	-	-
Neurogenic Bladder (n = 9)	-	5 (56)	4 (44)	-	-	-	-	-
Stricture Urethra (n = 2)	-	1 (50)		-	-	1 (50)*	-	-
Renal Stone (n = 27)	-	14 (52)	5 (19)	1 (4)	2 (7)	2 (7)	2 (7)	1 (4)
Indwelling urinary catheter (n = 18)	-	11 (61)	2 (11)	3 (17)	1 (6)	1 (6)	-	-
Pregnancy (n = 8)	-	3 (38)	2 (26)	1 (12)	1 (12)	-	1 (12)
Chronic Kidney Disease (n = 17)	-	11 (65)	4 (23)	-	-	-	1 (6)	1 (6)
Glomerulonephritis (n = 23)	-	11 (49)	7 (30)	3 (13)	1 (4)	1 (4)	-	-
Lupus Nephritis (n = 1)	-	-	-	-	1 (100)	-	-	-

Values shown as n (%); * denotes p < 0.05; ** denotes p < 0.01; *** denotes p < 0.001

Antibiotic susceptibility pattern of the isolated organisms

The antibiotic susceptibility patterns of the isolated uropathogens exhibited significant resistance trends among key organisms. E. coli, the most prevalent uropathogen, showed moderate to high resistance to Penicillins, Cephalosporins, and Quinolones, with notable resistance to Ciprofloxacin (55%) (Fig. 1). However, isolates of E. coli have shown sensitivity to Amikacin, Nitrofurantoin, and Carbapenems, ranging from 66 to 84%. K. pneumoniae, the second most identified isolate, has displayed moderate resistance to Ciprofloxacin (55%) but retained sensitivity to Gentamicin and Meropenem (74% and 67%, respectively). For the isolates of P. aeruginosa, they have demonstrated medium to moderate sensitivity to Carbapenem (38%) and Amikacin (63%), with moderate sensitivity to Meropenem (56%). E. faecalis showed moderate resistance to Ciprofloxacin (57%) but was highly sensitive to Linezolid (93%). A. baumannii exhibited high resistance to Ciprofloxacin (80%) but moderate to high sensitivity to Carbapenems. S. aureus isolates were highly resistant to Ciprofloxacin (100%), with 75% sensitivity to Linezolid and Vancomycin (Supplemental Tables 1–3).

Fig. 1.

Heatmap of antimicrobial susceptibility patterns. Each tile represents the proportion of isolates from a given organism that were sensitive, intermediate, or resistant to a specific antibiotic agent. Color intensity corresponds to the percentage

Discussion

In this study, we identified bacterial isolates and their antibiotic resistance patterns from urine samples of patients with cUTIS. Our findings highlight that E. coli and K. pneumoniae were the predominant uropathogens. The distribution of the bacterial isolates varied by gender and age. E. coli was more common in females, while P. aeruginosa and A. baumannii were found to be more prevalent in males. Among the complicating factors observed in cUTI patients, DM was the most prevalent, affecting 66% of cases, highlighting its role as a significant risk factor. Other common conditions included glomerulonephritis and the presence of an indwelling urinary catheter. Our observed resistance pattern of the bacterial isolates towards commonly prescribed antibiotics was alarming.

As seen from the findings of our study, E. coli accounted for 49% of all uropathogens isolated from patients with cUTI, making it the most common organism identified. Although data on the predominant uropathogens in cUTIs are limited in Bangladesh, our findings are consistent with previous studies on uncomplicated UTIs. Several studies from Bangladesh have reported E. coli as the most frequently isolated pathogen in UTI cases, with prevalence varying from 51% to 69% [3, 17, 35, 42]. As such, our finding of a 49% prevalence of E. coli is comparable to these previous studies. Similarly, research from neighbouring countries such as India, Pakistan, and Nepal have also identified E. coli as the most commonly detected uropathogen. However, the reported prevalence varied between 48% and 81% among different study populations and healthcare settings [43–45]. Additionally, the second most prevalent organism in this study is K. pneumoniae (24.7%), which was also found to have a similar prevalence in studies from other South Asian countries, ranging from 17.6% to 26% [45, 46]. Variations in prevalence rates of these uropathogens across different studies may be attributed to differences in study populations, geographical regions, healthcare settings, and antibiotic use practices.

Results from our study reveal that female participants were more likely to be affected by cUTI than their male counterparts. This higher prevalence in females can be attributed to anatomical and hormonal factors predisposing them to UTIs [47, 48]. Additionally, individuals aged between 50 and 65 years were found to be more susceptible to cUTIs compared to other age groups. Previous research has shown that people in the 55–59 age group experience a high incidence of UTIs, and the risk of developing UTIs increases with age [49, 50]. These findings highlight the greater vulnerability of females and older adults to cUTIs, emphasizing the need for targeted preventive measures and careful clinical attention in these demographics.

Based on the complicating factors observed in this study, DM, renal stones, and an indwelling urinary catheter were common factors observed among the patients in this study. Previous studies have shown that DM is a well-established risk factor for recurrent UTIs due to hyperglycemia, which promotes bacterial growth and impairs immune function [51]. Moreover, DM has been identified as a risk factor for developing cUTIs [52–54]. Similarly, renal stones were another key factor observed among study subjects. A previous long-term cohort study found that having a renal stone increases the 5.7-fold risk of developing UTI, eventually leading to cUTI due to structural and functional abnormalities in the urinary tract [55]. Also, indwelling urinary catheters facilitate biofilm formation, creating a protective harbour for uropathogens [56]. These biofilms protect bacteria from host immune responses and hinder antibiotic penetration, thereby contributing to persistent infections and increasing the risk of recurrent and cUTIs [40, 57]. Regular screening for UTIs in these patients, along with susceptibility test-guided antibiotic therapy, is essential to prevent further complications and improve disease outcomes.

Among patients with various complicating factors, renal allograft recipients demonstrated a significant association with both E. coli and P. aeruginosa in our study. This dual-pathogen burden reflects the unique vulnerability of transplant patients, who are subject to chronic immunosuppression, frequent hospital exposures, and urinary instrumentation [58, 59]. Although E. coli remains the most common uropathogen in immunocompromised hosts, infections with non-fermenting Gram-negative bacteria, such as P. aeruginosa, are increasingly being reported in renal transplant recipients [60–62]. These patterns raise critical concerns regarding empirical therapy, as multidrug resistance is often more prevalent in this subgroup [63]. Our findings thus support the need for enhanced antimicrobial stewardship, individualized risk assessment, and ongoing surveillance among renal transplant recipients to guide early and appropriate management.

Our results highlight concerning antibiotic resistance patterns in the uropathogens isolated from patients with cUTI. A significant portion of the E. coli isolates in this study showed resistance to Penicillin, Cephalosporins, and Quinolones. This is particularly alarming as it limits the effectiveness of commonly prescribed antibiotics for treating E. coli infections. The observed resistance to Penicillins and Cephalosporins is often attributed to the production of β-lactamases, enzymes that hydrolyze the β-lactam ring, rendering these antibiotics ineffective. Extended-spectrum β-lactamases (ESBLs) are mainly responsible for resistance to third-generation Cephalosporins [64]. Resistance to Quinolones, such as Ciprofloxacin, is primarily due to mutations in genes encoding DNA gyrase and topoisomerase IV, the target enzymes of these antibiotics. Additionally, overexpression of efflux pumps and plasmid-mediated resistance mechanisms contributes to decreased susceptibility [65].

Similarly, K. pneumoniae, the second most common pathogen, demonstrated notable resistance to Cephalosporins and Quinolones, which aligns with regional reports of ESBL-producing strains. A study from Southern Thailand found that 58.8% of K. pneumoniae isolates were ESBL producers, exhibiting high resistance to third-generation Cephalosporins and Quinolones [66]. However, its preserved sensitivity to Aminoglycosides and Carbapenems underscores the potential role of these antibiotics in severe infections. Meanwhile, caution is also needed when using Carbapenems to treat K. pneumoniae-related infections due to the increasing global reports of Carbapenem-resistant strains [67, 68]. Additionally, the sensitivity to Aminoglycosides suggests a viable treatment option, but its nephrotoxicity further necessitates cautious use, particularly in patients with renal impairment [69].

In contrast, P. aeruginosa displayed significant resistance to Aminoglycosides and Carbapenems, commonly seen in hospital-acquired strains that often carry multiple drug resistance mechanisms. Studies suggest that Carbapenem-resistant P. aeruginosa isolates frequently have aminoglycoside-modifying enzymes contributing to their strong resistance [70]. Moreover, the intermediate susceptibility to Colistin (56%) is particularly concerning, as colistin is often a last-resort antibiotic against resistant gram-negative infections. This suggests the need for alternative combination therapies, emphasizing the importance of exploring treatments that work together to improve effectiveness while reducing the risk of resistance.

Among gram-positive pathogens, E. faecalis and S. aureus exhibited high resistance to Quinolones, which is concerning given the limited treatment options for these pathogens in cUTIs. However, their sensitivity to Linezolid and Vancomycin suggests that these antibiotics remain effective against these pathogens. A study on enterococcal infections noted that Linezolid and Evernimicin showed the best activity against all enterococcal isolates [71]. Additionally, in our study, A. baumannii, a well-known nosocomial pathogen, showed alarmingly high resistance to Fluoroquinolones while retaining some sensitivity to Carbapenems, reflecting global trends in multidrug-resistant Acinetobacter infections. A systematic review reported that Carbapenem-resistant and multidrug-resistant A. baumannii accounted for 65% and 59% of all hospital-acquired infections among intensive care unit patients in Southeast Asia [72].

One of the major strengths of this study is its focus on cUTIs, an area with limited data in Bangladesh. By analyzing a diverse range of bacterial isolates and their antibiotic susceptibility patterns, our findings provide valuable insights into the current resistance trends, aiding clinicians in selecting appropriate empirical therapies. Furthermore, the study’s use of standardized laboratory techniques ensures the reliability of the microbiological data. However, we have several limitations too. To begin with, the study was conducted in a private hospital, so the findings may not be fully generalizable to other healthcare settings or the broader population of the country. Secondly, we did not assess age- or sex-specific differences in antimicrobial resistance due to small subgroup sizes, which limited the feasibility of meaningful statistical comparisons. Third, we did not perform molecular analysis to identify antibiotic resistance genes, which could have provided a deeper understanding of the underlying mechanisms of resistance. Lastly, patient-related factors such as prior antibiotic use and treatment history were not extensively analyzed, which may have influenced resistance patterns.

Conclusion

This study highlights the antimicrobial resistance patterns of common urinary pathogens in patients with cUTIs from a tertiary hospital in Bangladesh. E. coli (49%) and K. pneumoniae (25%) were identified as the most common uropathogens in patients of our study. These organisms showed high resistance to Fluoroquinolones and Cephalosporins, but retained susceptibility to carbapenems, aminoglycosides, and Fosfomycin. The next most frequently detected pathogen, P. aeruginosa, exhibited resistance across multiple drug classes, including aminoglycosides and carbapenems. These findings underscore the growing challenge of antimicrobial resistance in cUTI patients and emphasize the need for careful antibiotic selection and dose optimization, particularly in cases with intermediate susceptibility that may risk treatment failure with a standard regimen.

Our findings demonstrate the urgent need for more robust, multi-centre studies to track resistance trends among cUTI patients across healthcare facilities. Future research should focus on prioritizing molecular characterization of resistant strains, evaluating emerging resistance trends, and exploring novel or combination treatment strategies. Additionally, strengthening antimicrobial stewardship programs, particularly in LMICs such as Bangladesh, could also be essential to address the escalating threat of antibiotic resistance in cUTI patients.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

cUTI

Complicated Urinary Tract Infections

AMR

Antimicrobial resistance

LMIC

Low- and middle-income countries

DM

Diabetes Mellitus

ESBL

Extended-spectrum β-lactamases

CKD

Chronic Kidney Disease

Author contributions

SM conceptualised the study. SM, RR, and MEM collected data for the study. URM, HRS, ASP, and SM performed formal data analysis. HRS, ASP, SM, and URM prepared the primary draft of the manuscript. RR and MEM reviewed the paper and provided critical feedback. All the authors read and approved the final manuscript.

Funding

No funding was acquired for this study.

Data availability

The manuscript provides all relevant data. The datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The study protocol was reviewed and approved by the Ethical Review Committee of the Centre for Health Innovation, Research, Action and Learning—Bangladesh (CHIRAL Bangladesh) [Reference no. CHIBAN24DEC2022-003]. As the study involved retrospective analysis of medical records with no direct contact with patients and posed no risk of harm, the ethics committee waived the requirement for informed consent. All data were de-identified, and confidentiality was strictly maintained in accordance with the principles of the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.