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Keywords = multidrug-resistant urinary tract infections (MDR UTIs)

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30 pages, 745 KB  
Review
Biofilm-Mediated Antimicrobial Resistance in Pediatric Klebsiella pneumoniae Urinary Tract Infections: A Narrative Review of Mechanisms, Clinical Challenges, and Therapeutic Strategies
by Larisa Goroftei, Cristina-Mihaela Popescu, Irina Profir, Geanina-Adelina Jalba and Gabriela Gurau
Antibiotics 2026, 15(8), 783; https://doi.org/10.3390/antibiotics15080783 - 13 Aug 2026
Abstract
Urinary tract infections (UTIs) caused by Klebsiella pneumoniae are an increasing challenge in pediatric practice due to the combined effects of biofilm formation, multidrug resistance (MDR), and limited therapeutic options for children. Biofilm development promotes bacterial persistence by impairing antibiotic penetration, enabling metabolic [...] Read more.
Urinary tract infections (UTIs) caused by Klebsiella pneumoniae are an increasing challenge in pediatric practice due to the combined effects of biofilm formation, multidrug resistance (MDR), and limited therapeutic options for children. Biofilm development promotes bacterial persistence by impairing antibiotic penetration, enabling metabolic adaptation, promoting persister-cell formation, facilitating horizontal gene transfer (HGT), and inducing stress-induced mutagenesis, thereby reducing the effectiveness of conventional antimicrobial therapy. These mechanisms are further compounded by pediatric-specific challenges, including age-dependent pharmacokinetic variability, congenital urinary tract abnormalities, device-associated infections, and the limited availability of validated diagnostic tools for biofilm-associated infections. This narrative review integrates current knowledge of the molecular mechanisms underlying biofilm-mediated antimicrobial resistance with the unique diagnostic, pharmacological, and therapeutic challenges encountered in pediatric patients with K. pneumoniae UTIs. Emerging therapeutic strategies, such as optimized antibiotic combination therapy, bacteriophages, biofilm matrix-degrading enzymes, quorum-sensing inhibitors (QSIs), antimicrobial peptides (AMPs), and microbiome-directed approaches are critically evaluated with particular emphasis on their potential applicability in children. Although several anti-biofilm strategies have demonstrated encouraging results in experimental models, robust pediatric clinical evidence remains scarce. Current international guidelines continue to rely primarily on planktonic antimicrobial susceptibility testing without addressing biofilm-specific therapeutic considerations. In the absence of validated biofilm diagnostics, catheter stewardship and dosing optimization remain the most defensible clinical interventions available today. Broader translation of anti-biofilm strategies into pediatric practice will require dedicated pharmacokinetic studies, standardized biofilm diagnostics, and prospective clinical trials. Full article
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17 pages, 891 KB  
Article
Prevalence and Antimicrobial Resistance of Pseudomonas aeruginosa Recovered from Respiratory and Urinary Specimens in a Lebanese Hospital (2020–2025)
by Rana Barakat, Zeinab Ezzeddine, Rana El Haidari, Samara Hassan and Ghassan Ghssein
Infect. Dis. Rep. 2026, 18(4), 87; https://doi.org/10.3390/idr18040087 - 13 Aug 2026
Viewed by 18
Abstract
Background: Respiratory tract infections (RTIs) and urinary tract infections (UTIs) are among the most common infections in humans. It is estimated that millions of deaths occur each year worldwide due to these infections. Pseudomonas aeruginosa (P. aeruginosa), in particular, represents a [...] Read more.
Background: Respiratory tract infections (RTIs) and urinary tract infections (UTIs) are among the most common infections in humans. It is estimated that millions of deaths occur each year worldwide due to these infections. Pseudomonas aeruginosa (P. aeruginosa), in particular, represents a public health threat since it has a high ability to acquire resistance to different antibiotic classes. The aim of this study was to determine the prevalence and antimicrobial resistance patterns of P. aeruginosa isolates from patients with RTIs and UTIs in Lebanon. Methods: This retrospective study was performed during 2020–2022 and 2024–2025. Samples were collected from both inpatients and outpatients, where identification and isolation of bacteria were performed along with antibiotic susceptibility testing. Results: The overall prevalence of P. aeruginosa isolates in RTI cases over the study period was 10.9%, and that of UTI cases was 1.3%. The general antimicrobial resistance profile of P. aeruginosa isolates from RTI and UTI cases showed the highest resistance for Piperacillin–Tazobactam and Aztreonam, respectively. For RTIs, antibiotic resistance decreased from 48.1% in 2020 to 36.7% in 2025 and increased from 16.7% to 19.4% for UTIs. Conclusions: According to our research, P. aeruginosa with low antibiotic susceptibility is frequently found in isolated samples, highlighting the significant challenge in treating severe infectious illnesses. To choose focused and efficient antibiotic therapy for RTIs and UTIs and to stop the emergence of multidrug-resistant (MDR) bacteria, it is essential to accurately identify the pathogenic microorganisms and their antibiotic susceptibility patterns. Full article
(This article belongs to the Section Bacterial Diseases)
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17 pages, 1365 KB  
Article
Nitrofurantoin Susceptibility and the Landscape of Multidrug-Resistant Gram-Negative Uropathogens in Kidney Transplant Recipients During the First Post-Transplant Year
by Aminah Alghamdi, Ehab Hammad, Fatimah S. Alhamlan, Layla Alharbi, Reem Almaghrabi, Fatimah W. Alsmail and Taghreed A. Hafiz
Antibiotics 2026, 15(8), 769; https://doi.org/10.3390/antibiotics15080769 - 10 Aug 2026
Viewed by 121
Abstract
Background: Multidrug-resistant (MDR) Gram-negative urinary tract infections (UTIs) frequently complicate the first post-transplant year in kidney transplant (KTX) recipients. This study characterized patterns of uropathogen susceptibility, MDR prevalence, and predictors of MDR UTI in this population. Methods: In a single-center retrospective cross-sectional study [...] Read more.
Background: Multidrug-resistant (MDR) Gram-negative urinary tract infections (UTIs) frequently complicate the first post-transplant year in kidney transplant (KTX) recipients. This study characterized patterns of uropathogen susceptibility, MDR prevalence, and predictors of MDR UTI in this population. Methods: In a single-center retrospective cross-sectional study (KFSHRC, Riyadh; October 2024 to December 2025), 83 adult first-transplant recipients with a first-year Gram-negative UTI were included for analysis. Susceptibility was determined using VITEK 2/CLSI criteria, and MDR was defined according to Magiorakos/ECDC criteria. Results: Nitrofurantoin susceptibility varied significantly by species, with 89.2% in E. coli compared to 15.0% in K. pneumoniae (p < 0.001), supporting its use as a carbapenem-sparing option for E. coli but not for K. pneumoniae. Carbapenems and amikacin retained near-complete activity, whereas cephalosporins, ciprofloxacin, and trimethoprim-sulfamethoxazole exhibited resistance rates of 45 to 68%. K. pneumoniae (49.4%) and E. coli (44.6%) were the predominant uropathogens, and MDR accounted for 63.9% of episodes (95% CI 53.1 to 73.4). MDR was associated with UTI recurrence, prolonged hospitalization, and reduced microbiological eradication (69.8% vs. 86.7%). UTI recurrence was the only independent predictor of MDR status (adjusted OR, 3.99; 95% CI, 1.46 to 10.89; p = 0.007). No UTI-associated mortality occurred within one year. Conclusions: Species-directed therapy, such as nitrofurantoin for E. coli and carbapenems or aminoglycosides for broader coverage, combined with local surveillance and antimicrobial stewardship, is essential to preserve treatment options and protect graft function. Full article
(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)
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22 pages, 2382 KB  
Article
The Resistance Landscape of Uropathogens in a Romanian Tertiary Center: A 13-Month Single-Center Study with Focus on Klebsiella and Urease-Positive Organisms
by Oana Nicu-Canareica, Loredana Sabina Cornelia Manolescu, Maria Luiza Băean, Cosmin Medar, Cristian Nicu, Gabriela-Cristiana Ivan, Ștefana-Georgiana Tanasă, Theodor-Georgian Badea, Georgian-Florentin Nedelea, Alexandru Gabriel Berza, Vlad-Octavian Bolocan, Maria Glencora Costache, Gelu-Adrian Popa and Viorel Jinga
Microorganisms 2026, 14(7), 1491; https://doi.org/10.3390/microorganisms14071491 - 8 Jul 2026
Viewed by 404
Abstract
Urinary tract infections (UTIs) sit at a leading edge of the antimicrobial-resistance (AMR) crisis, and Romania ranks among the most affected European countries, yet large single-center series of urinary isolates with complete antibiograms remain scarce. We describe the full resistance landscape of urinary [...] Read more.
Urinary tract infections (UTIs) sit at a leading edge of the antimicrobial-resistance (AMR) crisis, and Romania ranks among the most affected European countries, yet large single-center series of urinary isolates with complete antibiograms remain scarce. We describe the full resistance landscape of urinary pathogens at a Romanian tertiary hospital, with particular attention to multidrug-resistant Klebsiella and to the often-overlooked urease-positive organisms. We analyzed all positive urine cultures processed over 13 consecutive months (February 2025–February 2026). The first isolate per patient was the primary unit of analysis (n = 2331); the full isolate-level dataset (n = 3348) was analyzed secondarily. Resistance phenotypes (putative ESBL, carbapenem resistance, MDR, VRE) were derived from per-agent susceptibility data following Magiorakos et al., and resistance rates were calculated only on tested isolates. Associations were tested with chi-square/Fisher tests and Benjamini–Hochberg correction. A total of 3348 isolates from 2331 unique patients were analyzed (median age 68 years; 55% male). Escherichia coli predominated (40.5%), followed by Enterococcus spp. (22.2%) and Klebsiella spp. (18.9%). Among the first isolates, 15.3% were MDR; 16.7% of E. coli, Klebsiella and Proteus showed a putative ESBL phenotype; and 3.9% of Enterobacterales were carbapenem-resistant. Resistance was concentrated in Klebsiella (36.2% MDR, 22.8% putative ESBL, 14.7% carbapenem-resistant; all higher than E. coli, p < 0.001) and in Pseudomonas spp. (48.1% carbapenem-resistant). E. coli retained excellent activity to nitrofurantoin (1.2%), fosfomycin (1.2%; tested in a subset) and ertapenem (0.1%) despite high trimethoprim–sulfamethoxazole (31.5%) and fluoroquinolone (24.3%) resistance. Urease-positive organisms formed a distinct subgroup with high trimethoprim–sulfamethoxazole resistance but preserved carbapenem activity. The urinary resistance burden was substantial but uneven, concentrated in Klebsiella and Pseudomonas. These findings support a stratified, locally guided empirical strategy and combined stewardship–infection control efforts. Full article
(This article belongs to the Special Issue Advances in Clinical Infections and Antimicrobial Resistance)
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15 pages, 1172 KB  
Article
Phenotypic Fosfomycin Susceptibility and Detection of Plasmid-Mediated Resistance Genes in Clinical Uropathogenic Escherichia coli Isolates
by Eman E. Hegazy, Esraa A. Mohamed, Shaimaa S. E. Marey, Aya Abdelrahman, Aysha Femy, Esraa Atef, Asmaa K. Hammad, Amira E. Oraiby, Ahmed Mostafa Elgohary, Ahmed Metawee Elsefy, Ahmed Boshnak and Manar M. Emara
Microorganisms 2026, 14(6), 1291; https://doi.org/10.3390/microorganisms14061291 - 8 Jun 2026
Viewed by 471
Abstract
Urinary tract infections (UTIs), predominantly caused by Escherichia coli, constitute a major global health issue due to the escalating antimicrobial resistance. This study was designed to assess the in vitro susceptibility of fosfomycin among clinical uropathogenic Escherichia coli (UPEC) isolates and to [...] Read more.
Urinary tract infections (UTIs), predominantly caused by Escherichia coli, constitute a major global health issue due to the escalating antimicrobial resistance. This study was designed to assess the in vitro susceptibility of fosfomycin among clinical uropathogenic Escherichia coli (UPEC) isolates and to detect plasmid-mediated fosA3 and fosC2 genes in those exhibiting fosfomycin resistance. A total of 158 non-duplicated UPEC strains were collected from urine samples of patients with UTIs. Antimicrobial susceptibility of these isolates was evaluated. Phenotypic detection of extended-spectrum β-lactamases (ESBL) and carbapenemase producers in UPEC was assessed. Identification of plasmid mediated fosA3 and fosC2 genes in those exhibiting fosfomycin resistance was carried out by PCR. A total of 72% of the isolates demonstrated multidrug resistance (MDR). Extensively drug-resistant (XDR) isolates represented 15%, while PDR isolates were rare (0.6%, 1/158). ESBLs were detected in 40% of the isolates, and 31% exhibited carbapenemase production. Fosfomycin resistance was detected in 9.5% of UPEC isolates, with the fosA3 gene identified in 33% of these resistant strains, whereas fosC2 gene was not identified in any isolate. Fosfomycin demonstrated considerable in vitro activity against carbapenemase-producing, ESBL-producing, and MDR isolates with susceptibility rates of 78%, 84%, and 97%, respectively. Fosfomycin resistance among UPEC isolates is emerging but still at a relatively low level of resistance. Continuous surveillance and antimicrobial stewardship are essential to preserve fosfomycin efficacy. Full article
(This article belongs to the Special Issue Antimicrobial Testing (AMT), Fourth Edition)
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13 pages, 252 KB  
Article
Impact of Multidrug-Resistant Uropathogens on Mortality in Elderly Patients with Urinary Tract Infections: A Multicenter Retrospective Study
by Pınar Yürük Atasoy, Sevil Alkan, Dilek Bulut, Pelin Beyza Ünal, Derya Seyman, Ayşegül Seremet Keskin, Ayşegül Tuna, Ahmet Şahin, Mustafa Serhat Şahinoğlu, Şafak Kaya, Yasemin Çağ, Nurşen Demirkol Kaya, Mehmet Çelik, Deniz Gür Altunay, Cumhur Artuk and Bircan Kayaaslan
Diagnostics 2026, 16(11), 1708; https://doi.org/10.3390/diagnostics16111708 - 2 Jun 2026
Cited by 1 | Viewed by 401
Abstract
Background/Objectives: Urinary tract infections (UTIs) in older adults are common and potentially life-threatening conditions that often present with atypical symptoms. Early identification of prognostic factors is essential to improve clinical outcomes and reduce mortality in this vulnerable population. Methods: This retrospective, multicenter study [...] Read more.
Background/Objectives: Urinary tract infections (UTIs) in older adults are common and potentially life-threatening conditions that often present with atypical symptoms. Early identification of prognostic factors is essential to improve clinical outcomes and reduce mortality in this vulnerable population. Methods: This retrospective, multicenter study included patients aged ≥65 years who were hospitalized with a diagnosis of UTI between January 2019 and December 2023. Diagnoses were established by infectious disease specialists based on clinical findings and microbiological confirmation in accordance with international guidelines. Only patients with urine cultures showing ≥100,000 CFU/mL bacterial growth were included. Demographic, clinical, laboratory, and microbiological data were analyzed. Multivariable logistic regression was used to identify independent predictors of in-hospital mortality. Results: A total of 1175 patients (median age: 75 years; 51.1% male) were included. The in-hospital mortality rate was 14.6%, and 25.6% required intensive care unit (ICU) admission. Multidrug-resistant (MDR) bacteria were detected in 63.6% of isolates, and bacteremia was present in 24.3% of cases. In multivariable analysis, MDR/ESBL positivity (OR: 2.09, 95% CI: 1.24–3.50, p = 0.005), bacteremia (OR: 2.10, 95% CI: 1.32–3.35, p = 0.002), and SOFA score (OR: 1.53, 95% CI: 1.42–1.65, p < 0.001) were independently associated with in-hospital mortality. Age and altered mental status were also significant predictors, while CRP and procalcitonin lost significance after adjustment. Conclusions: UTIs in elderly patients are associated with substantial morbidity and mortality. Multidrug-resistant pathogens, bacteremia, and disease severity play a central role in determining outcomes. Early identification of high-risk patients using clinical severity scores and microbiological data may improve risk stratification and guide timely, targeted therapeutic interventions. Full article
(This article belongs to the Section Diagnostic Microbiology and Infectious Disease)
19 pages, 609 KB  
Review
Resistance to Plazomicin: An Analysis of the Evidence from In Vitro Antimicrobial Susceptibility Studies
by George Fanariotis, Panagiota Poziou, Laura T. Romanos, Iva D. Tzvetanova and Matthew E. Falagas
Antibiotics 2026, 15(6), 559; https://doi.org/10.3390/antibiotics15060559 - 30 May 2026
Viewed by 571
Abstract
Introduction: Plazomicin, a novel, semi-synthetic aminoglycoside designed to overcome most aminoglycoside-modifying enzymes (AMEs), represents a therapeutic alternative to traditional aminoglycosides for complicated urinary-tract infections (cUTIs). In this review, we sought to evaluate the available data on drug resistance. Methods: We performed [...] Read more.
Introduction: Plazomicin, a novel, semi-synthetic aminoglycoside designed to overcome most aminoglycoside-modifying enzymes (AMEs), represents a therapeutic alternative to traditional aminoglycosides for complicated urinary-tract infections (cUTIs). In this review, we sought to evaluate the available data on drug resistance. Methods: We performed a thorough search across four databases (PubMed, Embase, Scopus, and Web of Science) from their inception to 4 November 2025 to identify relevant studies. The published Clinical and Laboratory Standards Institute (CLSI) antimicrobial susceptibility breakpoints for Enterobacterales were applied. Results: Fifty-five studies, out of a total of 905 records originally identified, were eligible for data extraction and analysis, yielding antimicrobial susceptibility data for 80,159 clinical isolates. The overall resistance of consecutive Enterobacterales isolates to plazomicin was 0–9.4%, and specifically for Escherichia coli and Klebsiella spp. isolates were up to 4.7% and 15.2%, respectively. Among selected isolates with specific resistance mechanisms, the resistance of carbapenem-resistant Enterobacterales (CRE) was 1.8–67.6%, and specifically for carbapenem-resistant E. coli and Klebsiella spp. isolates, 0–10% and 0.3–90%, respectively. Among multi-drug-resistant (MDR) isolates, up to 24.6% of MDR Klebsiella spp. isolates and up to 15% of MDR E. coli isolates were resistant to plazomicin. Among non-fermenting Gram-negative bacteria, the MIC90 values were consistently high. Conclusions: The demonstrated high activity of plazomicin against consecutive Enterobacterales isolates and the considerable, yet variable, activity against selected resistant isolates suggest its consideration as a valuable option in the treatment of complicated urinary-tract infections. Full article
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16 pages, 1704 KB  
Article
Epidemiology and Molecular Profiles of ESBL-Producing Klebsiella pneumoniae in Urinary Tract Infections Across Jordanian Hospitals
by Ayman Alsheikh, Raghad Shanabla, Ahmad Badawi, Hafez Al-Momani, Mohammed Nasser-Ali, Yaqeen Rjoub, Mohammad A. A. Al-Najjar, Montasir Al-Mansi, Iman Aolymat, Lana Al-Shoubaki and Nawal Al-Zaa’q
Microorganisms 2026, 14(5), 1142; https://doi.org/10.3390/microorganisms14051142 - 19 May 2026
Viewed by 790
Abstract
Klebsiella pneumoniae is an opportunistic pathogen associated with both community-acquired and nosocomial infections. Multidrug-resistant (MDR) strains are increasingly implicated in urinary tract infections (UTIs), traveller’s diarrhoea, bacteraemia, and sepsis. β-lactam antibiotics are commonly used for treatment; however, antimicrobial resistance has emerged largely due [...] Read more.
Klebsiella pneumoniae is an opportunistic pathogen associated with both community-acquired and nosocomial infections. Multidrug-resistant (MDR) strains are increasingly implicated in urinary tract infections (UTIs), traveller’s diarrhoea, bacteraemia, and sepsis. β-lactam antibiotics are commonly used for treatment; however, antimicrobial resistance has emerged largely due to the production of extended-spectrum β-lactamases (ESBLs), which confer resistance mainly to penicillins, oxyimino-cephalosporins, and monobactams, while cephamycins and carbapenems usually remain stable to ESBL-mediated hydrolysis and compromise therapeutic efficacy. ESBL-producing strains represent a major cause of severe Gram-negative infections. This study aimed to determine the prevalence of ESBL-producing K. pneumoniae among UTI patients in Jordanian hospitals (Al Mafraq, Ma’an, and Islamic Hospitals), evaluate their antimicrobial susceptibility patterns, and detect antimicrobial resistance genes at the molecular level. A total of 450 urine isolates of K. pneumoniae were collected from UTI patients between November 2023 and May 2024. Isolates were identified in hospital laboratories using standard microbiological methods. Antimicrobial susceptibility testing was performed, and molecular characterisation of ESBL-associated genes was conducted using polymerase chain reaction (PCR). Out of 450 K. pneumoniae isolates collected from UTI patients across three Jordanian regions, 72 (16%) were confirmed as ESBL producers. Among the 72 ESBL-positive K. pneumoniae isolates, 34 (47.2%) were recovered from the Central region, 20 (27.8%) from the North, and 18 (25.0%) from the South. Molecular analysis revealed that 41.7% of ESBL-producing isolates carried the blaCTX-M gene, while 33.3% harboured the blaOXA gene. All ESBL-producing isolates demonstrated antimicrobial resistance to third-generation cephalosporins. A significantly higher proportion of ESBL-producing isolates was identified in female patients (84.7%) compared with males (15.3%). A significant association was observed between blaOXA gene distribution and geographic region (p = 0.016), whereas blaCTX-M gene distribution showed no significant regional association. ESBL-producing K. pneumoniae accounted for a substantial proportion of UTI isolates in Jordan, with blaCTX-M identified as the predominant resistance gene. The higher burden observed in the Central region and among female patients highlights notable distribution patterns in this cohort. These findings emphasise the necessity for sustained molecular surveillance and strengthened antimicrobial stewardship strategies to limit the dissemination of ESBL-producing strains in Jordanian healthcare settings. Full article
(This article belongs to the Section Medical Microbiology)
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20 pages, 1720 KB  
Article
Antimicrobial Resistance in Pediatric UTIs with Congenital Urogenital Anomalies: An 11-Year Saudi Retrospective Study
by Fuad Alanazi and Basmah M. Almaarik
Antibiotics 2026, 15(5), 506; https://doi.org/10.3390/antibiotics15050506 - 18 May 2026
Viewed by 490
Abstract
Background/Objectives: Children with congenital urogenital anomalies (CUA) face increased risk of urinary tract infections (UTIs) and may harbor resistant organisms due to recurrent infections and antibiotic exposure. This study characterized the distribution of uropathogens and antimicrobial resistance patterns at a tertiary center in [...] Read more.
Background/Objectives: Children with congenital urogenital anomalies (CUA) face increased risk of urinary tract infections (UTIs) and may harbor resistant organisms due to recurrent infections and antibiotic exposure. This study characterized the distribution of uropathogens and antimicrobial resistance patterns at a tertiary center in Saudi Arabia. Methods: This retrospective cohort study included pediatric patients (<18 years) with documented congenital urogenital anomalies and positive urine cultures at King Khalid University Hospital, Riyadh (2015–2025). Susceptibility interpretations (S/I/R) were extracted from the hospital laboratory information system; multidrug resistance (MDR) was defined using organism-specific Magiorakos criteria. Results: A total of 168 patients (72.0% male; mean age 4.1 ± 4.5 years) contributed 411 UTI episodes. Among 403 mono-organism episodes (after excluding eight polymicrobial cultures), Escherichia coli predominated (150/403, 37.2%), followed by Klebsiella pneumoniae (96/403, 23.8%) and Pseudomonas aeruginosa (33/403, 8.2%). High resistance was observed for ampicillin (83.6%), trimethoprim-sulfamethoxazole (54.2%), and cephalosporins (cefazolin 62.8%, cefotaxime 35.6%). Carbapenems (2.9%) and aminoglycosides (9.2%) retained >90% susceptibility. Overall MDR was 35.5%, highest among Klebsiella oxytoca (57.1%) and Escherichia coli (47.6%). Recurrent infections showed numerically higher unadjusted resistance than single episodes. Conclusions: Pediatric patients with congenital urogenital anomalies showed high first-line antibiotic resistance. Carbapenems and aminoglycosides retained predominantly susceptible in vitro profiles in this cohort and may inform empiric considerations alongside ongoing local susceptibility surveillance for this high-risk population. Full article
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13 pages, 251 KB  
Article
A Microbiological Indicator of Multidrug Resistance in Feline Urinary Tract Infections: Antimicrobial Resistance Patterns in Cats in Portugal
by Paula Segura Rodrigues, Bárbara Durão Feitor, Maria João Fonseca, André Marcelo Conceição Meneses and Joana Tavares de Oliveira
Vet. Sci. 2026, 13(5), 419; https://doi.org/10.3390/vetsci13050419 - 24 Apr 2026
Viewed by 944
Abstract
Antimicrobial resistance (AMR) is an increasing concern in veterinary medicine and may compromise empirical treatment of feline urinary tract infections (UTIs). This retrospective observational study evaluated antimicrobial resistance patterns and their association with multidrug resistance (MDR) in bacterial isolates obtained from urine cultures [...] Read more.
Antimicrobial resistance (AMR) is an increasing concern in veterinary medicine and may compromise empirical treatment of feline urinary tract infections (UTIs). This retrospective observational study evaluated antimicrobial resistance patterns and their association with multidrug resistance (MDR) in bacterial isolates obtained from urine cultures of cats presented to a feline referral practice in Lisbon, Portugal, between January 2023 and December 2025. A total of 174 cats with positive urine cultures were included, yielding 178 bacterial isolates. Escherichia coli was the most frequent pathogen (57.30%), followed by Enterococcus spp. (16.98%) and Staphylococcus spp. (14.61%). Antimicrobial resistance was detected in 107/178 isolates (60.11%), and 76/178 (42.70%) were classified as multidrug-resistant. Extended-spectrum beta-lactamase-producing Escherichia coli and methicillin-resistant Staphylococcus strains were also identified. Resistance to penicillins and fluoroquinolones was significantly associated with MDR (p < 0.001). These findings highlight the high burden of antimicrobial resistance in feline urinary isolates in this clinical setting and support routine urine culture and susceptibility testing to guide therapeutic decision-making, particularly in recurrent, complicated, or high-risk cases. Full article
(This article belongs to the Section Veterinary Biomedical Sciences)
18 pages, 2623 KB  
Article
Characterization of Antimicrobial Resistance and Potential Zoonotic Risk in Uropathogenic Escherichia coli Isolated from Companion Animals, with Genomic Analysis of Virulence Determinants in a Representative Isolate
by Asanka R. DeZoysa, Madeline Kwan, Lekshmi K. Edison, Rebecca Barber, Lisa Glick, Thomas Denagamage and Subhashinie Kariyawasam
Trop. Med. Infect. Dis. 2026, 11(4), 101; https://doi.org/10.3390/tropicalmed11040101 - 13 Apr 2026
Viewed by 1139
Abstract
Uropathogenic Escherichia coli (UPEC) is a leading cause of urinary tract infections (UTIs) in companion animals. This study characterized 42 UPEC isolates recovered from dogs and cats at the University of Florida, College of Veterinary Medicine Diagnostic Laboratories between 2023 and 2024, focusing [...] Read more.
Uropathogenic Escherichia coli (UPEC) is a leading cause of urinary tract infections (UTIs) in companion animals. This study characterized 42 UPEC isolates recovered from dogs and cats at the University of Florida, College of Veterinary Medicine Diagnostic Laboratories between 2023 and 2024, focusing on antimicrobial resistance (AMR), virulence gene profiles, biofilm-forming ability, and phylogroup distribution of the isolates. Antimicrobial susceptibility testing (AST) showed that 40.48% of the isolates were resistant to at least one of the tested antibiotics, and 9.52% exhibited multidrug resistance (MDR). Phylogroup B2 was predominant (69.05%), and 61.90% of isolates demonstrated strong biofilm formation in artificial human urine. Virulence gene analysis revealed the presence of genes mediating adhesion (fim, pap, sfa), iron acquisition (fyuA, iro), biofilm formation (csg, bcs, pga, ycg/ymg), motility (fli, mot, flh), and stress response (oxyR, soxR/S, kat). Multiple plasmids carrying AMR and virulence determinants were also identified. The co-occurrence of the traits underscores the potential for persistent and recurrent infections, which can complicate therapeutic outcomes and facilitate horizontal gene transfer (HGT). The detection of antimicrobial-resistant, highly virulent UPEC strains possessing human UPEC traits in companion animals suggests the risk of zoonotic and reverse-zoonotic transmission, particularly in households with close pet–owner interactions. These findings emphasize the importance of judicious antimicrobial use, routine molecular surveillance, and integrated One Health strategies to mitigate the veterinary and public health threats associated with UPEC infections in companion animals. Full article
(This article belongs to the Special Issue Zoonotic Pathogens and Antimicrobial Resistance)
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19 pages, 3743 KB  
Article
Phylogenetic Groups, Virulence Factors, and Antimicrobial Susceptibility of Escherichia coli Associated with Urinary Tract Infections from a Metropolitan Area of Buenos Aires, Argentina
by Nora B. Molina, Ramón A. González Pasayo, Marisa A. López and Mónica D. Sparo
Antibiotics 2026, 15(4), 350; https://doi.org/10.3390/antibiotics15040350 - 29 Mar 2026
Cited by 2 | Viewed by 1600
Abstract
Background: Uropathogenic Escherichia coli (UPEC) is the primary etiological agent of urinary tract infections (UTIs) worldwide. The emergence of strains combining high virulence with multidrug resistance (MDR) poses a significant challenge to public health. This study aimed to characterize the phylogenetic distribution, virulence [...] Read more.
Background: Uropathogenic Escherichia coli (UPEC) is the primary etiological agent of urinary tract infections (UTIs) worldwide. The emergence of strains combining high virulence with multidrug resistance (MDR) poses a significant challenge to public health. This study aimed to characterize the phylogenetic distribution, virulence profiles, and antimicrobial susceptibility of UPEC isolates recovered from patients in the metropolitan area of Buenos Aires (AMBA), Argentina. Methodology: Phylogenetic groups, the ST131 lineage, and virulence-associated genes were identified using PCR-based assays. Antimicrobial susceptibility testing (AST) was performed using automated methods and extended-spectrum beta-lactamase (ESBL) production was confirmed using the double-disk synergy test. Colistin (COL) resistance was evaluated by Colistin Drop Test and PCR screening for the mcr-1 (mobile colistin resistance gene 1). Biofilm formation was detected by the Tissue Culture Plate (TCP) method, whereas phenotypic virulence factors (VF) were assessed with Congo Red agar, hemagglutination, and hemolysis assays. Results: Phylogenetic groups B2 (43.8%) and D (26.7%), typically associated with extraintestinal infections, were the most frequent. The high-risk clone B2-ST131 was detected in 6.7% of isolates. Biofilm production was observed in 92.4% of the isolates, with curli fimbriae (87.6%) being the most frequently expressed VF. The highest resistance rates were observed for ampicillin (62.1%), ampicillin-sulbactam (39.8%), and trimethoprim-sulfamethoxazole (25.2%). Interestingly, 3.8% of isolates exhibited colistin resistance, despite the absence of the mcr-1 gene. Conclusions: This study highlights the detection of MDR-UPEC isolates that showed strong resistance to fluoroquinolones and were ESBL producers with high virulence in Argentina, justifying future research encompassing genomic and epidemiological monitoring of local UPEC, which is essential for managing infections and developing new therapeutic and preventive measures. Full article
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62 pages, 2709 KB  
Review
A One Health Perspective on Proteus mirabilis: The Interaction of Virulence and Antimicrobial Resistance Across Human and Animal Reservoirs
by Ibtisam Faeq Hasona, Amal Awad, Gamal Younis and Wafaa Farouk Mohamed
Microorganisms 2026, 14(2), 444; https://doi.org/10.3390/microorganisms14020444 - 12 Feb 2026
Cited by 4 | Viewed by 2554
Abstract
Proteus mirabilis (P. mirabilis), a common commensal and opportunistic pathogen, circulates freely across interconnected human, animal, and environmental reservoirs, embodying the One Health concept. Its key virulence factors—urease activity, swarming motility, and biofilm formation—drive severe urinary tract infections, particularly catheter-associated ones. [...] Read more.
Proteus mirabilis (P. mirabilis), a common commensal and opportunistic pathogen, circulates freely across interconnected human, animal, and environmental reservoirs, embodying the One Health concept. Its key virulence factors—urease activity, swarming motility, and biofilm formation—drive severe urinary tract infections, particularly catheter-associated ones. These virulence traits concurrently facilitate the acquisition and dissemination of antimicrobial resistance (AMR) via mobile genetic elements, leading to extensively drug-resistant clones. Epidemiological and genomic evidence confirms that identical multidrug-resistant clones and resistance mechanisms (ESBLs, carbapenemases) are shared among human clinical isolates, livestock, food products, and environmental samples. This demonstrates continuous, multi-directional transmission through interconnected zoonotic, foodborne, and environmental pathways. The synergistic convergence of potent virulence and escalating AMR within shared reservoirs heightens public health risks. Effective containment therefore demands integrated One Health strategies: enhanced cross-sectorial surveillance, stringent antimicrobial stewardship, robust infection control, and the creation of novel treatments. A coordinated global response is crucial to curb the spread of resistant P. mirabilis and preserve antibiotic efficacy. Full article
(This article belongs to the Special Issue One Health: Innovations in Emerging Infectious Disease Research)
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13 pages, 613 KB  
Article
Prevalence, Determinants, and Temporal Dynamics of Multidrug-Resistant Gram-Negative Bacilli in Urinary Tract Infection Patients from Central Portugal (2018–2022)
by Muhammad Adnan, Patrícia Coelho, Miguel Castelo-Branco and Francisco José Barbas Rodrigues
Bacteria 2026, 5(1), 8; https://doi.org/10.3390/bacteria5010008 - 2 Feb 2026
Cited by 1 | Viewed by 896
Abstract
Background: Multidrug-resistant (MDR) Gram-negative bacilli (GNBs) significantly compromise the effective management of urinary tract infections (UTIs) worldwide. As antimicrobial resistance varies across regions, locally tailored data are essential to guide empirical therapy. This study investigated the prevalence, determinants, and temporal dynamics of MDR [...] Read more.
Background: Multidrug-resistant (MDR) Gram-negative bacilli (GNBs) significantly compromise the effective management of urinary tract infections (UTIs) worldwide. As antimicrobial resistance varies across regions, locally tailored data are essential to guide empirical therapy. This study investigated the prevalence, determinants, and temporal dynamics of MDR GNBs in UTI patients from Central Portugal between 2018 and 2022. Methods: We conducted a retrospective observational study at a hospital center in Central Portugal, analyzing data from 2018 to 2022. Data from 5194 UTI patients with GNB-positive cultures were analyzed. Binary logistic regression was used to identify determinants of MDR GNBs, defined as resistance to ≥1 agent in ≥3 antibiotic classes. Results: The study population had a mean age of 64.5 ± 25.3 years, and females represented two-thirds of the sample (67.0%). The overall prevalence of MDR GNBs was 35.8%. Advanced age (≥75 years), male sex, and specific treatment contexts—particularly day treatment and laboratory-only cases—were independently associated with MDR. SBL-producing Enterobacterales and non-fermenting GNBs showed the highest risk levels. Conclusions: MDR GNBs are highly prevalent among UTI patients in Central Portugal, and their increasing trend—particularly in 2022—highlights an urgent need for strengthened surveillance and updated empirical treatment strategies. The observed temporal increase highlights the urgent need for strengthened regional surveillance and updated empirical treatment guidelines. Full article
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31 pages, 1311 KB  
Article
Mapping Escherichia coli in Women with Simple Urinary Tract Infections: Phenotypic ESBL/AmpC Screening and Whole-Genome Insights from Oman
by Aisha Al-Mufarji, Meher Rizvi, Nawal Al-Kindi, Nada Al-Tamtami and Zaaima Al-Jabri
Antibiotics 2026, 15(2), 124; https://doi.org/10.3390/antibiotics15020124 - 27 Jan 2026
Viewed by 1256
Abstract
Background/Objectives: Simple urinary tract infections (sUTIs) are common in women and increasingly affected by multidrug-resistant (MDR) Escherichia coli. Extended-spectrum β-lactamase (ESBL) and AmpC producers restrict oral treatment options and promote carbapenem use. This study aimed to (i) describe the etiology and antimicrobial [...] Read more.
Background/Objectives: Simple urinary tract infections (sUTIs) are common in women and increasingly affected by multidrug-resistant (MDR) Escherichia coli. Extended-spectrum β-lactamase (ESBL) and AmpC producers restrict oral treatment options and promote carbapenem use. This study aimed to (i) describe the etiology and antimicrobial susceptibility of sUTIs in women of reproductive age in Oman, (ii) determine the prevalence of ESBL/AmpC-producing E. coli, (iii) evaluate nitroxoline, fosfomycin, mecillinam, and temocillin against ESBL and non-ESBL E. coli, and (iv) characterize circulating clones and resistance/virulence determinants using whole-genome sequencing (WGS). Methods: In this multicentric study (September 2022–August 2023), 795 uropathogens from 762 women (15–50 years) with sUTI were collected from four Omani hospitals. Identification and susceptibility testing of E. coli (n = 489) and Klebsiella pneumoniae (n = 140) using BD Phoenix and MALDI-TOF MS was performed (CLSI 2022). Thirty ESBL-producing and 82 non-ESBL E. coli underwent phenotypic ESBL/AmpC testing and evaluation of mecillinam, temocillin, nitroxoline, and fosfomycin. WGS was performed on 26 isolates (23 ESBL, 3 wild type) and analyzed for MLST, and SNP phylogeny using ResFinder, CARD, PlasmidFinder, VirulenceFinder. Statistical significance was set at p < 0.05. Results: E. coli (62%) and K. pneumoniae (18%) were the predominant pathogens. E. coli showed high susceptibility to nitrofurantoin (~97%), carbapenems, aminoglycosides, and piperacillin–tazobactam, but reduced susceptibility to cephalosporins, fluoroquinolones, cotrimoxazole, and ampicillin. ESBL prevalence ranged from 38–51%; AmpC producers were rare (4.6%). Mecillinam, nitroxoline, and fosfomycin exhibited 100% activity against both ESBL and non-ESBL isolates; temocillin showed 89.3% activity in ESBL strains. WGS identified 15 sequence types dominated by ST-131, ST-1193, ST-73, and ST-174, with blaCTX-M-15 as the major ESBL genotype. Conclusions: sUTIs in Oman show a high burden of ESBL-producing E. coli. Nitrofurantoin, mecillinam, fosfomycin, temocillin, and nitroxoline would be effective carbapenem-sparing oral options. Continuous phenotypic and genomic surveillance are crucial to guide antimicrobial therapy and stewardship. Full article
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