Abstract
Urinary tract infections (UTIs) are among the most prevalent bacterial infections in both community and healthcare settings. In this study, we conducted a retrospective analysis of 1,516 urinary tract infection (UTI) patients (1,179 inpatients and 337 outpatients) at the Fourth Affiliated Hospital of Soochow University between January 1, 2021, and December 31, 2024. The study aimed to compare clinical characteristics, pathogen distribution, and antibiotic resistance profiles between outpatient and inpatient UTI cases. Key findings revealed a significantly higher urine culture positivity rate in females compared to males, with this gender disparity being more pronounced among outpatients. The peak age of UTI onset varied between groups: inpatients (both sexes) and male outpatients exhibited the highest incidence in the 70-79-year age group, whereas female outpatients peaked earlier (50-59 years). Escherichia coli (E. coli) remained the predominant pathogen in both cohorts, though its prevalence was higher in outpatients. In contrast, inpatients displayed greater microbial diversity, with a broader spectrum of isolated pathogens. E. coli and Enterococcus isolates from inpatients demonstrated higher overall antibiotic resistance than those from outpatients. These findings underscore distinct epidemiological and resistance patterns between outpatient and inpatient UTI cases, providing critical insights for optimizing empirical antibiotic therapy and reinforcing the need for tailored antimicrobial stewardship strategies in these populations.
Keywords
Urinary Tract Infection, Outpatients, Inpatients, Pathogens, Antibiotic Resistance
1. Introduction
Urinary tract infections (UTIs), also known as urinary system infections, rank among the most common healthcare-associated and community-acquired infections globally. These inflammatory conditions arise from the invasion of pathogenic microorganisms, predominantly bacteria, but also fungi, into the urinary tract
| [1] | Zalewska-Piatek B, Nagorka M, Phages as potential life-saving therapeutic option in the treatment of multidrug-resistant urinary tract infections [J]. Acta Biochim Pol, 2025, 72: 14264. https://doi.org/10.3389/abp.2025.14264 |
[1]
. Typical clinical manifestations include bladder irritation symptoms such as dysuria, urinary frequency, and urgency. The majority of UTIs are caused by bacterial pathogens, which exploit weakened host defenses, including impaired urethral mucosal immunity due to factors like urinary obstruction, vesicoureteral reflux, neurogenic bladder dysfunction, or structural urinary tract abnormalities
. Following entry via ascending, hematogenous, or lymphatic routes, these pathogens adhere to urothelial cells via virulence factors, proliferate, and ultimately establish infection
| [3] | Johnson J R, Johnston B D, Thuras P, Phylogenetic groups and extraintestinal virulence genes of inflow Escherichia coli entering a municipal drinking water treatment facility (St. Paul, MN, USA) [J]. Microbiology (Reading), 2025, 171(3). https://doi.org/10.1099/mic.0.001542 |
[3]
. Notably, UTIs often exhibit a recurrent or persistent course, with severe cases potentially progressing to complications such as pyelonephritis, renal failure, bacteremia, or sepsis. These sequelae are associated with poor clinical outcomes and increased mortality risk
.
In China, UTIs represent the second most prevalent infection, with age, sex, and comorbidities constituting major risk determinants. The incidence is markedly higher in women aged 16-64 compared to men, with particularly elevated rates observed among pregnant women, elderly populations, and patients with malignancies, diabetes mellitus, or indwelling urinary catheters
. In clinical practice, urine culture with drug sensitivity testing remains essential for accurate UTI diagnosis and appropriate treatment selection
. Despite extensive research on UTI epidemiology, systematic comparisons of these distinct care environments remain limited-an important gap given their divergent antibiotic use patterns, pathogen distributions, and resistance profiles. The comparison is clinically imperative because inpatients face higher multidrug-resistant infections requiring broad-spectrum therapy, while outpatients can often be treated with targeted agents. These differences reflect varied antibiotic selection pressures and have direct consequences for treatment guidelines. Our findings provide evidence to tailor antimicrobial policies, improve resource allocation, and develop setting-specific stewardship approaches-critical needs in the era of rising antimicrobial resistance. Significant geographical and clinical setting variations exist in both pathogen distribution and resistance profiles, with distinct patterns emerging between community-acquired and hospital-acquired infections. Study showed Catheter-associated urinary tract infection (CA-UTI) was significantly higher among outpatients than inpatients (82.2% v 35.3%)
| [7] | Ndomba A L M, Laisser R M, Silago V, Kidenya B R, Mwanga J, Seni J, Mshana S E, Urinary Tract Infections and Associated Factors among Patients with Indwelling Urinary Catheters Attending Bugando Medical Centre a Tertiary Hospital in Northwestern Tanzania [J]. Microorganisms, 2022, 10(2). https://doi.org/10.3390/microorganisms10020473 |
[7]
. Surveillance data from Jordan revealed
Escherichia coli (
E. coli) was the most common causative pathogen (50.6%), followed by
Klebsiella pneumonia (
K. pneumoniae, 10.8%). Moreover, high rates of resistance to cefazolin and ticarcillin were identified
| [8] | Amawi H A, U'Wais H T, Nusair M B, Al-Okour R, Amawi S, Al-Shatnawi S, Abdi A, Management of urinary tract infections and antibiotic susceptibility patterns of bacterial isolates [J]. Int J Clin Pract, 2021, 75(10): e14475. https://doi.org/10.1111/ijcp.14475 |
[8]
. These epidemiological differences likely arise from complex interplay of environmental factors, patient comorbidities, and antibiotic usage patterns, indicating divergent microbial ecosystems between community and hospital UTI cases.
In this study, we analyzed 1,516 UTI cases from our hospital, comparing clinical situation, pathogen distribution, and antibiotic resistance profiles between outpatient and inpatient populations. This study aims to elucidate local UTI epidemiology, identify differential resistance patterns to guide clinical decision-making, and provide a foundation for optimizing antibiotic stewardship in both outpatient and inpatient settings.
2. Results
2.1. Age and Gender Distribution of Urinary Tract Infections in Outpatients and Inpatients
Our study cohort comprised 1,516 patients with culture-confirmed urinary tract infections, consisting of 1,179 inpatients (77.8%) and 337 outpatients (22.2%). Male inpatients accounted for 34.8% (528/1516) of all positive cultures Female inpatients represented 42.9% (651/1516) of cases. The female-to-male ratio among inpatients was 1.23:1. Male outpatients constituted 4.2% (64/1516) of positive cultures. Female outpatients comprised 18.0% (273/1516) of cases. The female-to-male ratio among outpatients was 4.27:1. A significantly higher proportion of female patients was found in both care settings (
P < 0.001). The aforementioned results revealed a more pronounced female predominance in outpatient cases compared to inpatient cases. Our study revealed distinct epidemiological patterns in UTI occurrence across different patient populations
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[9]
. For male inpatients, female inpatients, and male outpatients, the highest incidence occurred in the 70-79 years age group. Female outpatients showed a significantly younger peak incidence at 50-59 years (p<0.05 compared to other groups). Statistically significant variations in UTI incidence were observed across genders in both inpatient and outpatient populations aged 0-69 years (all
P < 0.05,
Table 1).
Table 1. Age and gender distribution of UTIs in outpatients and inpatients.
Age (years) | Inpatients [No. (%)] | Outpatients [No. (%)] | P Value |
Male | Female | Total | Male | Female | Total |
0-19 | 5(0.33) | 3(0.20) | 8(0.53) | 4(0.26) | 14(0.92) | 18(1.19) | 0.046 |
20-29 | 21(1.39) | 24(1.58) | 45(2.97) | 5(0.33) | 42(2.77) | 47(3.10) | 0 |
30-39 | 28(1.85) | 42(2.77) | 70(4.62) | 1(0.07) | 46(3.03) | 47(3.10) | 0 |
40-49 | 36(2.37) | 52(3.43) | 88(5.80) | 3(0.20) | 34(2.24) | 37(2.44) | 0 |
50-59 | 70(4.62) | 120(7.92) | 190(12.53) | 11(0.73) | 50(3.30) | 61(4.02) | 0.006 |
60-69 | 133(8.77) | 144(9.50) | 277(18.27) | 13(0.86) | 48(3.17) | 61(4.02) | 0 |
70-79 | 155(10.22) | 177(11.68) | 332(21.90) | 23(1.52) | 29(1.91) | 52(3.43) | 0.741 |
80-89 | 74(4.88) | 79(5.21) | 153(10.09) | 4(0.26) | 9(0.59) | 13(0.86) | 0.222 |
90-99 | 6(0.40) | 10(0.66) | 16(1.06) | 0(0.00) | 1(0.07) | 1(0.07) | 0.446 |
Total | 528(34.83) | 651(42.94) | 1179(77.77) | 64(4.22) | 273(18.01) | 337(22.23) | 0 |
2.2. Comparative Analysis of Pathogen Distribution in Urinary Tract Infections Between Outpatient and Inpatient Settings
A total of 1916 non-repetitive microbial isolates were obtained from 1516 UTI patients. From the 1,179 inpatients, we identified 1,553 unique isolates representing 72 distinct microbial species. Gram-negative bacteria predominated 70.7% (n = 1,098), gram-positive organisms accounted for 28.53% (n=443), and fungal isolates were rare (n=12, 0.77%). The five most frequently isolated pathogens were
E. coli (n=605, 38.96%),
Enterococcus faecium (
E. faecium, n=182, 11.72%),
Klebsiella pneumoniae (
K. pneumoniae
, n=155, 9.98%),
Enterococcus faecalis (
E. faecalis, n=134, 8.63%),
Proteus mirabilis (
P. mirabilis, n=71, 4.57%). These five pathogens collectively represented 73.86% of all inpatient isolates, demonstrating a characteristic UTI microbiological profile with clear
Enterobacterales dominance (
E. coli,
K. pneumoniae,
P. mirabilis), significant enterococcal representation (
E. faecium and
E. faecalis), and the expected Gram-negative predominance in hospitalized UTI cases. From 337 outpatient UTI cases, we identified 363 non-repetitive microbial isolates representing 28 distinct species, including gram-negative predominance 314 isolates (86.5%), gram-positive bacteria 48 isolates (13.22%) and fungal isolates extremely rare (1 isolate, 0.28%). The outpatient microbiological spectrum showed marked differences from inpatient isolates. The isolation rate of
E. coli (253 strains, 69.70%) was the highest in outpatients, followed by
K. pneumoniae and
P. mirabilis (both 19 strains, 5.23%),
E. faecalis (16 strains, 4.41%), and Streptococcus agalactiae (
S. agalactiae, 14 strains, 3.86%). The complete pathogen distribution patterns, including less frequent isolates, are detailed in
Table 2. Statistical analysis revealed significant differences (
P <0.05) in detection rates between care settings for
E. coli (higher in outpatients),
E. faecium (higher in inpatients),
K. pneumoniae,
E. faecalis,
S. aureus. No significant differences were observed for other pathogens, suggesting distinct ecological niches for uropathogens in different care settings
| [10] | Zandbergen L E, Halverson T, Brons J K, Wolfe A J, de Vos M G J, The Good and the Bad: Ecological Interaction Measurements Between the Urinary Microbiota and Uropathogens [J]. Front Microbiol, 2021, 12: 659450. https://doi.org/10.3389/fmicb.2021.659450 |
[10]
. Possible healthcare-associated factors influencing pathogen distribution
. The outpatient population demonstrates a more focused pathogen profile dominated by
E. coli, which is consistent with previous epidemiological report
| [12] | Frisbie L, Weissman S J, Kapoor H, D'Angeli M, Salm A, Radcliff J, Rabinowitz P, Outpatient Antibiotic Resistance Patterns of Escherichia coli Urinary Isolates Differ by Specialty Type [J]. Microbiol Spectr, 2022, 10(4): e0237321. https://doi.org/10.1128/spectrum.02373-21 |
[12]
. These findings highlight the importance of setting-specific empirical treatment guidelines and infection control measures tailored to the expected microbiological spectrum in different patient populations.
Table 2. Pathogen spectrum variation between inpatients and outpatients of UTIs.
Pathogens | Inpatients [No. (%)] | Outpatients [No. (%)] | P value |
Gram negative bacteria | 1098(70.70) | 314(86.50) | 0 |
Escherichia coli | 605(38.96) | 253(69.70) | 0 |
Klebsiella pneumoniae | 155(9.98) | 19(5.23) | 0.005 |
Proteus mirabilis | 71(4.57) | 19(5.23) | 0.591 |
Pseudomonas aeruginosa | 40(2.58) | 5(1.38) | 0.175 |
Acinetobacter baumannii | 18(1.16) | 1(0.28) | 0.126 |
Enterobacter hormaechei | 30(1.93) | 2(0.55) | 0.065 |
Enterobacter cloacae | 7(0.45) | 0(0.00) | 0.2 |
Other gram negative bacteria | 172(11.08) | 15(4.13) | 0 |
Gram positive bacteria | 443(28.53) | 48(13.22) | 0 |
Enterococcus faecium | 182(11.72) | 4(1.10) | 0 |
Enterococcus faecalis | 134(8.63) | 16(4.41) | 0.007 |
Streptococcus agalactiae | 37(2.38) | 14(3.86) | 0.116 |
Staphylococcus aureus | 26(1.67) | 1(0.28) | 0.042 |
Staphylococcus epidermidis | 19(1.22) | 1(0.28) | 0.11 |
Other gram positive bacteria | 45(2.90) | 12(3.31) | 0.68 |
Fungi | 12(0.77) | 1(0.28) | 0.299 |
Candida albicans | 8(0.52) | 0(0.00) | 0.171 |
Candida glabrata | 3(0.19) | 1(0.28) | 0.757 |
Candida tropicalis | 1(0.06) | 0(0.00) | 0.629 |
Total | 1553(100.00) | 363(100.00) | |
2.3. Antibiotic Resistance Profiles of Common Uropathogens
Our analysis revealed distinct antimicrobial resistance profiles between inpatient and outpatient isolates of key uropathogens. The study focused on
E. coli as the predominant Gram-negative pathogen and
Enterococcus species (
E. faecium and
E. faecalis) as the primary Gram-positive isolates. Inpatient
E. coli isolates exhibited significantly higher resistance rates compared to outpatient isolates across most antibiotic classes (
P <0.05), with two notable exceptions: Ampicillin and Amoxicillin/clavulanic acid.
E. coli from both patient sources demonstrated near-universal susceptibility to colistin and tigecycline (resistance ≤ 0.5%). In addition, the resistance rates to several carbapenem antibacterial drugs were also very low, such as ertapenem (resistance 3.8% inpatients, 0.8% outpatients), meropenem (resistance 2.1% inpatients, 0.4% outpatients), imipenem (resistance 1.5% inpatients, 0.2% outpatients). Both inpatients and outpatients showed high resistance to fluoroquinolones and cephalosporins. In detail, ciprofloxacin resistance reached 67.93% (inpatients) vs 56.13% (outpatients). The resistance rate of ceftriaxone in inpatients was 56.10% and that of cefazolin was 60.79%, while in outpatients, the resistance rates of ceftriaxone and cefazolin were 30.40% and 38.77% respectively. The antibiotic resistance profiles of
E. coli in outpatient and inpatient urinary tract infection patients are shown in
Figure 1. These results demonstrate significant setting-specific differences in antimicrobial resistance profiles, emphasizing the need for differentiated empirical treatment approaches based on patient care setting. The preserved susceptibility to carbapenems and last-resort antibiotics provides important therapeutic options for multidrug-resistant infections.
Inpatient isolates of
Enterococcus (
E. faecium and
E. faecalis) showed higher resistance rates to most antibiotics compared to outpatients, except for tetracycline, minocycline, gentamicin, and rifampicin. Clindamycin and gentamicin had the highest resistance rates in both groups, but resistance was more pronounced in inpatients (95.57% for clindamycin and 94.62% for gentamicin, respectively) than outpatients (85% for both). Clindamycin, gentamicin, erythromycin, ciprofloxacin, tetracycline, oxacillin, and levofloxacin showed high resistance in inpatients (>60%). The
Enterococcus from outpatients had the high resistance to clindamycin, gentamicin, tetracycline, erythromycin, and minocycline (>60%). Antibiotics with retained sensitivity in both outpatients and inpatients are fosfomycin, linezolid, teicoplanin, and vancomycin. No vancomycin-resistant
Enterococcus (VRE) reported in this dataset. The drug sensitivity of
Enterococcus in outpatient and inpatient urinary tract infection patients is shown in
Figure 2. The higher resistance in inpatients suggests nosocomial pressure and possible cross-transmission of resistant strains, emphasizing the need for antimicrobial stewardship and infection prevention measures in hospitals.
Figure 1. Antimicrobial resistance profiles of Escherichia coli.
Figure 2. Antimicrobial resistance profiles of Enterococcus.
3. Materials and Methods
3.1. Study Subjects
A total of 1516 patients with culture-confirmed UTIs from midstream urine samples who visited the Fourth Affiliated Hospital of Soochow University were recruited from January 1, 2021, to December 31, 2024, were collected. Among them, 1,179 were hospitalized patients, and 337 were outpatients. A total of 1916 non-repetitive pathogens were isolated and cultured for antimicrobial susceptibility testing (AST), including 1553 isolates from inpatients and 363 isolates from outpatients. The demographic characteristics, pathogen distribution, and antibiotic resistant profiles of common pathogens in inpatients and outpatients were analyzed.
3.2. Sample Collection and Inoculation
All urine specimens were collected using standardized aseptic techniques, including clean-catch midstream urine, clean-catch midstream urine and suprapubic bladder aspiration. Collected specimens were transported immediately to the clinical microbiology laboratory in sterile containers, and processed within 2 hours for culture. 10 μL of the urine was inoculated onto a Columbia blood agar and MacConkey agar plates. The plate was inverted and incubated in a 35°C, 5% CO2 incubator for 18-24 h.
3.3. Culture and Identification of Bacteria
Positive cultures were defined according to the Clinical & Laboratory Standards Institutes. MALDI-TOF mass spectrometry (Bruker Biotyper) was used for species-level identification of isolated colonies according to manufacturer’s protocol. Isolates were subsequently subjected to AST. The shipment of samples and the evaluation of bacterial contaminants were based on in-house guidelines.
3.4. Antimicrobial Susceptibility Testing (AST)
For bacterial identification and antimicrobial susceptibility testing, we employed a BD Phoenix™ M50 automated microbiology system (Becton Dickinson, USA) as the primary method. To ensure comprehensive resistance profiling, supplementary Kirby-Bauer (K-B) disk diffusion tests were performed when required. For gram-negative bacteria, Ciprofloxacin, Levofloxacin, Norfloxacin, Cefazolin, Tetracycline, Cefuroxime, Ceftriaxone, Trimethoprim/Sulfamethoxazole (TMP-SMX), Moxifloxacin, Aztreonam, Cefepime, Gentamicin, Ampicillin/Sulbactam, Ceftazidime, Chloramphenicol, Tobramycin, Minocycline, Cefoperazone/Sulbactam, Ampicillin, Cefoxitin, Amoxicillin/Clavulanic acid, Ertapenem, Fosfomycin, Piperacillin/Tazobactam, Nitrofurantoin, Amikacin, Meropenem, Imipenem, Colistin, and Tigecycline were tested. For gram-positive bacteria, Penicillin, Nitrofurantoin, Ampicillin, Norfloxacin, Minocycline, Gentamicin synergy, Moxifloxacin, Streptomycin synergy, Daptomycin, Fosfomycin, Linezolid, Teicoplanin, Rifampicin, and Vancomycin were tested. All antimicrobial susceptibility results were interpreted strictly in accordance with the Clinical and Laboratory Standards Institute (CLSI) M100 performance standards (2024 edition).
3.5. Statistical Analysis
IBM SPSS Statistics 11 software was used for statistical analysis. The chi - square test was used for the comparison of rates, and P < 0.05 was considered statistically significant.
4. Discussion
This study retrospectively analyzed 1,516 patients with confirmed UTI who showed positive urine culture results at our hospital. The investigation focused on examining gender and age distribution patterns, identifying commonly isolated pathogens, and assessing antibiotic resistance profiles to frequently used antimicrobial agents in both outpatient and inpatient settings. In both outpatient and inpatient settings, the urine culture positivity rate was significantly higher in females than in males, which aligns with well-established anatomical differences between the sexes. The female urethra is shorter and in closer proximity to the anus and vagina, facilitating bacterial colonization and increasing susceptibility to UTIs
| [13] | Schmiemann G, Kranz J, Mandraka F, Schubert S, Wagenlehner F, Gagyor I, The Diagnosis, Treatment, and Prevention of Recurrent Urinary Tract Infection [J]. Dtsch Arztebl Int, 2024, 121(11): 373-382. https://doi.org/10.3238/arztebl.m2024.0068 |
[13]
. Notably, this gender disparity was more pronounced among outpatients, possibly because women tend to seek medical attention earlier due to greater symptom awareness, leading to higher detection rates even in mild cases. Age-related trends also varied by gender and patient setting. The peak incidence of UTIs occurred at 70-79 years for male and female inpatients as well as male outpatients, whereas female outpatients exhibited an earlier peak at 50-59 years. Advanced age is a well-documented risk factor for UTIs due to immunosenescence, declining physiological function, and reduced urinary tract defenses
. The earlier peak in female outpatients may be attributed to hormonal changes during perimenopause and menopause. Declining estrogen levels lead to thinning of the vaginal and urethral mucosa, compromising local immunity and increasing infection risk. Furthermore, significant differences in UTI incidence were observed between genders in both inpatients and outpatients aged 20-69 years. This variation may be influenced by the higher prevalence of comorbidities among hospitalized patients and the frequent use of invasive procedures, which further predispose them to infections
| [14] | Rosado M R, Molina A G, Velasco A L, Chinchilla G C, Lana P V, Izquierdo E O, Vidal L S, Urinary Tract Infection in Pediatrics: Study of Uropathogens and Their Resistance in a Madrid Hospital [J]. Arch Esp Urol, 2022, 75(9): 791-797. https://doi.org/10.56434/j.arch.esp.urol.20227509.115 |
[14]
.
E. coli
was the predominant pathogen identified, representing 70.8% of clinically significant positive pure-growth cultures, and served as the most frequent causative agent in both community-acquired and hospital-acquired urinary tract infections
| [15] | Toval F, Kohler C D, Vogel U, Wagenlehner F, Mellmann A, Fruth A, Schmidt M A, Karch H, Bielaszewska M, Dobrindt U, Characterization of Escherichia coli isolates from hospital inpatients or outpatients with urinary tract infection [J]. J Clin Microbiol, 2014, 52(2): 407-418. https://doi.org/10.1128/JCM.02069-13 |
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[15, 16]
. It has been reported that the fimbriae of
E. coli can easily bind to the mannitol receptors on the uroepithelial cells, resulting in a high chance of infection
| [17] | Zeng J, Hong Y, Zhao N, Liu Q, Zhu W, Xiao L, Wang W, Chen M, Hong S, Wu L, Xue Y, Wang D, Niu J, Drlica K, Zhao X, A broadly applicable, stress-mediated bacterial death pathway regulated by the phosphotransferase system (PTS) and the cAMP-Crp cascade [J]. Proc Natl Acad Sci U S A, 2022, 119(23): e2118566119. https://doi.org/10.1073/pnas.2118566119 |
[17]
. A striking disparity was observed in
E. coli isolation rates between inpatients (38.96%) and outpatients (69.70%), with nearly a two-fold difference. Furthermore, inpatient samples yielded a significantly greater diversity of pathogens (72 species) compared to outpatient cases (28 species). This pattern likely reflects several factors: (1) prior antibiotic exposure in hospitalized patients, (2) nosocomial cross-infection risks, (3) potential reinfection episodes during hospitalization, and (4) frequent use of indwelling catheters. Notably, opportunistic pathogens including
Proteus spp.,
Acinetobacter spp., and
Pseudomonas aeruginosa were more prevalent among inpatients, warranting particular attention in clinical management
| [18] | Shen L, Fu T, Huang L, Sun H, Wang Y, Sun L, Lu X, Zhang J, Yang Z, Ni C, 7295 elderly hospitalized patients with catheter-associated urinary tract infection: a case-control study [J]. BMC Infect Dis, 2023, 23(1): 825. https://doi.org/10.1186/s12879-023-08711-0 |
[18]
. Additionally,
Enterococcus species (particularly
E. faecium and
E. faecalis) demonstrated higher isolation frequencies in hospitalized patients. As the predominant Gram-positive uropathogens,
enterococci possess remarkable environmental persistence, surviving for extended periods on dry surfaces. Their transmission is facilitated through healthcare workers' hands and contaminated medical equipment. More critically, enterococci employ biofilm formation on catheters and uroepithelial surfaces as a virulence strategy, enabling immune evasion and antibiotic resistance while promoting chronic or recurrent infections
| [19] | Schiopu P, Toc D A, Colosi I A, Costache C, Ruospo G, Berar G, Galbau S G, Ghilea A C, Botan A, Pana A G, Neculicioiu V S, Todea D A, An Overview of the Factors Involved in Biofilm Production by the Enterococcus Genus [J]. Int J Mol Sci, 2023, 24(14). https://doi.org/10.3390/ijms241411577 |
[19]
.
A retrospective analysis of UTI cases in our hospital revealed that clinicians frequently prescribe empirical antibiotic therapy, primarily third-generation cephalosporins (e.g., cefdinir), second-generation cephalosporins (e.g., cefaclor), and quinolones (e.g., levofloxacin). However, antimicrobial susceptibility testing demonstrated concerning resistance patterns among E. coli isolates from both inpatients and outpatients. Notably, E. coli exhibited high resistance rates to quinolones (ciprofloxacin, levofloxacin, norfloxacin), compromising their clinical utility. Outpatient E. coli isolates showed resistance rates of 47.43% to sulfonamides and 42.29% to tetracyclines, indicating limited efficacy of these agents.
These findings suggest that empirical treatment with second- or third-generation cephalosporins and quinolones may fail to adequately cover a substantial proportion of outpatient UTI cases. For complicated UTIs, clinicians should prioritize culture-guided antibiotic selection based on susceptibility results to optimize therapeutic outcomes
| [20] | Edlund C, Ternhag A, Skoog Stahlgren G, Edquist P, Ostholm Balkhed A, Athlin S, Mansson E, Tempe M, Bergstrom J, Giske C G, Hanberger H, Temocillin Study G, The clinical and microbiological efficacy of temocillin versus cefotaxime in adults with febrile urinary tract infection, and its effects on the intestinal microbiota: a randomised multicentre clinical trial in Sweden [J]. Lancet Infect Dis, 2022, 22(3): 390-400. https://doi.org/10.1016/S1473-3099(21)00407-2 |
[20]
. While
E. coli remains highly susceptible to carbapenems (making them a last-line option for multidrug-resistant infections), their use must be judicious due to the risk of inducing further resistance. To mitigate the emergence of carbapenem-resistant strains, strict adherence to prescribing guidelines and antimicrobial stewardship principles is essential.
The findings of this study provide valuable guidance for optimizing UTI management in clinical practice. Treatment strategies should be tailored according to patient setting (outpatient vs inpatient), demographic characteristics (gender and age), and local resistance patterns. For outpatient management, clinicians should exercise caution when prescribing empirical antibiotics, particularly second- and third-generation cephalosporins and quinolones, due to increasing resistance patterns
| [21] | Esposito S, Biasucci G, Pasini A, Predieri B, Vergine G, Crisafi A, Malaventura C, Casadio L, Sella M, Pierantoni L, Gatti C, Paglialonga L, Sodini C, La Scola C, Bernardi L, Autore G, Canto G D, Argentiero A, Cantatore S, Ceccoli M, De Fanti A, Suppiej A, Lanari M, Principi N, Pession A, Iughetti L, Antibiotic Resistance in Paediatric Febrile Urinary Tract Infections [J]. J Glob Antimicrob Resist, 2022, 29: 499-506. https://doi.org/10.1016/j.jgar.2021.11.003 |
[21]
Culture-guided therapy should be prioritized based on susceptibility results, with alternative agents considered for high-risk patients. Inpatient care requires antimicrobial stewardship, enhanced infection control (hand hygiene, environmental disinfection, aseptic catheterization), and nosocomial infection monitoring. Patient education should emphasize perineal hygiene, hydration, and early symptom recognition, with targeted prevention for high-risk groups. Carbapenems should be reserved for confirmed multidrug-resistant infections. Local resistance surveillance is essential to guide empirical therapy and track emerging patterns.
5. Limitations
Several important limitations should be considered when interpreting our findings. First, the single-center retrospective design inherently reflects local antibiotic prescribing patterns and institutional patient demographics, which may restrict the external validity of our results to other healthcare settings with different practice patterns. Second, although our study incorporates a substantial patient cohort (n=1,516) and employs standardized microbiological methods, the retrospective nature precluded collection of detailed prior antibiotic exposure history, potentially confounding our resistance pattern analysis. Third, the lack of associated clinical outcome data limits our ability to correlate microbiological findings with treatment efficacy or patient prognosis. Additionally, our resistance patterns were consistent with the data from China Antimicrobial Resistance Surveillance Network (CHINET) during the study period, particularly regarding the high prevalence of E. coli among both inpatient and outpatient isolates. However, some minor discrepancies were noted, such as a slightly higher resistance rate to fluoroquinolones in our inpatient population (42.3% vs CHINET's 38.7% national average), which may reflect regional prescribing habits or local bacterial epidemiology. These comparisons reinforce the clinical relevance of our findings while highlighting the need for ongoing regional surveillance to monitor emerging resistance trends. Future studies incorporating molecular characterization of resistance mechanisms would further enhance our understanding of these epidemiological patterns.
6. Conclusions
This study reveals distinct differences in uropathogen profiles and resistance patterns between outpatient and inpatient UTIs, with E. coli dominating community-acquired infections while inpatients exhibit greater microbial diversity and higher resistance rates. To optimize management, we recommend culture-guided therapy for outpatients and antimicrobial stewardship for inpatients, coupled with enhanced infection control measures including strict hand hygiene and proper catheter care. Preventive strategies should focus on patient education regarding hygiene and hydration, particularly for high-risk populations. Crucially, carbapenems should be reserved for confirmed resistant cases, supported by ongoing local resistance surveillance. These multidisciplinary strategies aim to enhance treatment outcomes while curbing antimicrobial resistance development in UTI management.
Abbreviations
UTI | Urinary Tract Infection |
E. coli | Escherichia coli |
CA-UTI | Catheter-associated Urinary Tract Infection |
K. pneumoniae | Klebsiella pneumonia |
E. faecium | Enterococcus faecium |
VRE | Vancomycin-Resistant Enterococcus |
AST | Antimicrobial Susceptibility Testing |
K-B | Kirby-bauer |
TMP-SMX | Trimethoprim/Sulfamethoxazole |
CLSI | Clinical and Laboratory Standards Institute |
CHINET | China Antimicrobial Resistance Surveillance Network |
Author Contributions
Liting Zhou: Conceptualization, Data curation, Methodology, Formal Analysis, Writing – original draft
Ruru Bi: Data curation, Methodology, Formal Analysis
Jianjun Cheng: Data curation, Methodology
Junmei Zhu: Data curation, Methodology
Yan Chen: Data curation, Methodology
Qingzhen Han: Supervision
Lin Wang: Supervision, Funding acquisition
Ting Zhang: Data curation, Supervision, Writing – review & editing
Funding
This work is supported by Innovation Research Project on Medical and Health Care in Suzhou Industrial Park (Grant No. CXYJ2024A08).
Data Availability Statement
The data is available from the corresponding author upon reasonable request.
Conflicts of Interest
The authors declare no conflicts of interest.
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APA Style
Zhou, L., Bi, R., Cheng, J., Zhu, J., Chen, Y., et al. (2025). Comparative Analysis of Clinical Situation, Pathogen Distribution, and Antibiotic Resistance in Urinary Tract Infections Between Outpatients and Inpatients. Clinical Medicine Research, 14(3), 49-57. https://doi.org/10.11648/j.cmr.20251403.12
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ACS Style
Zhou, L.; Bi, R.; Cheng, J.; Zhu, J.; Chen, Y., et al. Comparative Analysis of Clinical Situation, Pathogen Distribution, and Antibiotic Resistance in Urinary Tract Infections Between Outpatients and Inpatients. Clin. Med. Res. 2025, 14(3), 49-57. doi: 10.11648/j.cmr.20251403.12
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AMA Style
Zhou L, Bi R, Cheng J, Zhu J, Chen Y, et al. Comparative Analysis of Clinical Situation, Pathogen Distribution, and Antibiotic Resistance in Urinary Tract Infections Between Outpatients and Inpatients. Clin Med Res. 2025;14(3):49-57. doi: 10.11648/j.cmr.20251403.12
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@article{10.11648/j.cmr.20251403.12,
author = {Liting Zhou and Ruru Bi and Jianjun Cheng and Junmei Zhu and Yan Chen and Qingzhen Han and Lin Wang and Ting Zhang},
title = {Comparative Analysis of Clinical Situation, Pathogen Distribution, and Antibiotic Resistance in Urinary Tract Infections Between Outpatients and Inpatients
},
journal = {Clinical Medicine Research},
volume = {14},
number = {3},
pages = {49-57},
doi = {10.11648/j.cmr.20251403.12},
url = {https://doi.org/10.11648/j.cmr.20251403.12},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.cmr.20251403.12},
abstract = {Urinary tract infections (UTIs) are among the most prevalent bacterial infections in both community and healthcare settings. In this study, we conducted a retrospective analysis of 1,516 urinary tract infection (UTI) patients (1,179 inpatients and 337 outpatients) at the Fourth Affiliated Hospital of Soochow University between January 1, 2021, and December 31, 2024. The study aimed to compare clinical characteristics, pathogen distribution, and antibiotic resistance profiles between outpatient and inpatient UTI cases. Key findings revealed a significantly higher urine culture positivity rate in females compared to males, with this gender disparity being more pronounced among outpatients. The peak age of UTI onset varied between groups: inpatients (both sexes) and male outpatients exhibited the highest incidence in the 70-79-year age group, whereas female outpatients peaked earlier (50-59 years). Escherichia coli (E. coli) remained the predominant pathogen in both cohorts, though its prevalence was higher in outpatients. In contrast, inpatients displayed greater microbial diversity, with a broader spectrum of isolated pathogens. E. coli and Enterococcus isolates from inpatients demonstrated higher overall antibiotic resistance than those from outpatients. These findings underscore distinct epidemiological and resistance patterns between outpatient and inpatient UTI cases, providing critical insights for optimizing empirical antibiotic therapy and reinforcing the need for tailored antimicrobial stewardship strategies in these populations.
},
year = {2025}
}
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TY - JOUR
T1 - Comparative Analysis of Clinical Situation, Pathogen Distribution, and Antibiotic Resistance in Urinary Tract Infections Between Outpatients and Inpatients
AU - Liting Zhou
AU - Ruru Bi
AU - Jianjun Cheng
AU - Junmei Zhu
AU - Yan Chen
AU - Qingzhen Han
AU - Lin Wang
AU - Ting Zhang
Y1 - 2025/05/29
PY - 2025
N1 - https://doi.org/10.11648/j.cmr.20251403.12
DO - 10.11648/j.cmr.20251403.12
T2 - Clinical Medicine Research
JF - Clinical Medicine Research
JO - Clinical Medicine Research
SP - 49
EP - 57
PB - Science Publishing Group
SN - 2326-9057
UR - https://doi.org/10.11648/j.cmr.20251403.12
AB - Urinary tract infections (UTIs) are among the most prevalent bacterial infections in both community and healthcare settings. In this study, we conducted a retrospective analysis of 1,516 urinary tract infection (UTI) patients (1,179 inpatients and 337 outpatients) at the Fourth Affiliated Hospital of Soochow University between January 1, 2021, and December 31, 2024. The study aimed to compare clinical characteristics, pathogen distribution, and antibiotic resistance profiles between outpatient and inpatient UTI cases. Key findings revealed a significantly higher urine culture positivity rate in females compared to males, with this gender disparity being more pronounced among outpatients. The peak age of UTI onset varied between groups: inpatients (both sexes) and male outpatients exhibited the highest incidence in the 70-79-year age group, whereas female outpatients peaked earlier (50-59 years). Escherichia coli (E. coli) remained the predominant pathogen in both cohorts, though its prevalence was higher in outpatients. In contrast, inpatients displayed greater microbial diversity, with a broader spectrum of isolated pathogens. E. coli and Enterococcus isolates from inpatients demonstrated higher overall antibiotic resistance than those from outpatients. These findings underscore distinct epidemiological and resistance patterns between outpatient and inpatient UTI cases, providing critical insights for optimizing empirical antibiotic therapy and reinforcing the need for tailored antimicrobial stewardship strategies in these populations.
VL - 14
IS - 3
ER -
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