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Search Results (512)

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Keywords = extended-spectrum beta-lactamase

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19 pages, 313 KB  
Article
Fluoroquinolone Prophylaxis Uncovers High Prevalence Rates of Fluoroquinolone-Resistant Enterobacterales Colonization in Multiple Myeloma Autologous Transplant Patients: A Prospective Cohort Study
by Chintan Patel, Austin J. Terlecky, Melissa Baker, Tara Lozy, Kelly K. Yen, Navjot Kaur, Lauren Machere, Alaa Ali, Christina Cho, Michele L. Donato, Pashna N. Munshi, Barry N. Kreiswirth and Scott D. Rowley
Cancers 2026, 18(10), 1566; https://doi.org/10.3390/cancers18101566 - 12 May 2026
Viewed by 289
Abstract
Background: Fluoroquinolone prophylaxis during autologous stem cell transplantation (aSCT) reduces the risk of fever but raises the risk of bloodstream infection (BSI) with fluoroquinolone-resistant Enterobacterales (FRE). We performed a prospective cohort study to detect the presence and potential gain or loss of colonic [...] Read more.
Background: Fluoroquinolone prophylaxis during autologous stem cell transplantation (aSCT) reduces the risk of fever but raises the risk of bloodstream infection (BSI) with fluoroquinolone-resistant Enterobacterales (FRE). We performed a prospective cohort study to detect the presence and potential gain or loss of colonic FRE colonization using serial sampling before and after aSCT in a uniform population of patients with a diagnosis of multiple myeloma. Methods: Eligible subjects underwent aSCT after conditioning with dose-intense melphalan, 200 mg/m2. Peri-anal swabs were obtained before aSCT, upon hospital discharge, and 12–16 weeks after transplantation. Samples were cultured in tryptic soy broth supplemented with either ciprofloxacin or ceftriaxone with subsequent plating onto selective chromogenic agar designed to facilitate recovery and differentiation of Enterobacterales. Results: FRE colonization on pre-transplant sampling was detected for 23 of 117 subjects (19.7%) and 29 of 98 (29.6%) subjects at hospital discharge after a course of fluoroquinolone (116/117 subjects) prophylaxis (p < 0.001) and 28 of 92 (30.4%) subjects at 12–16 weeks. Including all three sampling time points, 48 of 117 subjects (41.0%) tested positive for FRE colonization. In total, 58 of the 90 FRE isolates (64.4%) from 48 subjects expressed extended-spectrum beta-lactamase (ESBL). Three FRE-colonized subjects developed FRE BSI. Bloodstream isolates for two subjects were identical to the organisms identified on pre-transplant sampling. Conclusions: We hypothesize that fluoroquinolone prophylaxis of subjects with undetected low levels of FRE colonization allows the expansion of the FRE population, placing subjects at risk of BSI with fluoroquinolone-resistant (and ESBL-expressing) Enterobacterales. Pre-transplant testing for FRE colonization permits patient-specific design of prophylactic and empiric antibiotic regimens. Full article
(This article belongs to the Section Transplant Oncology)
11 pages, 1668 KB  
Article
Contrasting In Vitro Activity of Nitroxoline Against Multidrug-Resistant Escherichia coli and Klebsiella pneumoniae Isolates from Outpatients
by Dominik Maleš, Zvonimir Barišić, Darko Kero and Merica Carev
Antibiotics 2026, 15(5), 479; https://doi.org/10.3390/antibiotics15050479 - 8 May 2026
Viewed by 324
Abstract
Background/Objectives: Antimicrobial resistance is a major public health concern, particularly among multidrug-resistant (MDR) Enterobacterales. Nitroxoline is an older antibiotic with a unique mechanism of action that has not been widely used in recent decades. This study aimed to evaluate the in vitro [...] Read more.
Background/Objectives: Antimicrobial resistance is a major public health concern, particularly among multidrug-resistant (MDR) Enterobacterales. Nitroxoline is an older antibiotic with a unique mechanism of action that has not been widely used in recent decades. This study aimed to evaluate the in vitro activity of nitroxoline against Extended-Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli (E. coli) and MDR Klebsiella pneumoniae (K. pneumoniae) isolated from urine samples of outpatients in Split-Dalmatia County, Croatia. Methods: Nitroxoline susceptibility was assessed using disk diffusion for E. coli (n = 26) and broth microdilution for K. pneumoniae (n = 33). Results: ESBL-producing E. coli isolates showed high susceptibility to nitroxoline, with 25 (96.2%) classified as susceptible. In contrast, K. pneumoniae isolates exhibited high minimum inhibitory concentration (MIC) values (range 16–128 mg/L; median 32 mg/L), indicating limited activity. Conclusions: Nitroxoline demonstrated strong in vitro activity against ESBL-producing E. coli but limited activity against MDR K. pneumoniae. Interpretation of the findings for K. pneumoniae is constrained by the lack of established clinical breakpoints. Full article
(This article belongs to the Section Mechanism and Evolution of Antibiotic Resistance)
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17 pages, 4614 KB  
Article
Antimicrobial Resistance and Phylo-Groups of Escherichia coli at the Human–Primate Interface in Gabon: A One Health Study
by Marie-louise Mawili Mounguengui, Richard Onanga, Anicet-Clotaire Dikoumba, Yann Mouanga-Ndzime, Gabriel Falque, Aicha Mohamed Ali, Léonce F. Ondjiangui, Leresche E. D. Oyaba Yinda, Ivan Mfouo-Tynga, Linaa Y. Okomo Nguema, Jean Nzue Nguema, Thierry A. G. Tsoumbou, Serge E. Dibakou, Désiré Otsaghe Ekore, Barthélémy Ngoubangoye and Sylvain Godreuil
Antibiotics 2026, 15(5), 446; https://doi.org/10.3390/antibiotics15050446 - 29 Apr 2026
Viewed by 344
Abstract
Background/Objectives: Antimicrobial resistance (AMR) is a global threat to human, animal, and environmental health. Among bacteria, E. coli is frequently used as a key indicator of AMR. Despite their genetic proximity to humans, studies on AMR in Non-Human Primates (NHPs) remain limited, particularly [...] Read more.
Background/Objectives: Antimicrobial resistance (AMR) is a global threat to human, animal, and environmental health. Among bacteria, E. coli is frequently used as a key indicator of AMR. Despite their genetic proximity to humans, studies on AMR in Non-Human Primates (NHPs) remain limited, particularly in semi-anthropized environments. This study aims to characterize the antibiotic resistance profiles and phylo-groups of E. coli isolated from NHPs and humans at a primatology center. Methods: A total of 143 stool samples were collected, including 125 from NHPs and 18 from humans. Isolates were cultured on Eosin Methylene Blue agar and then identified by MALDI-TOF mass spectrometry. Antibiotic susceptibility was assessed using the Kirby–Bauer disk diffusion method, with 30 antibiotics following CASFM-EUCAST recommendations. E. coli phylo-groups were characterized by quadruplex PCR according to the Clermont method, targeting the genes. Results: A total of 122 E. coli isolates (85.31%) were recovered, with comparable prevalence observed across NHPs and human staff. More than half of the isolates (55.74%) were resistant to at least one antibiotic tested, and 12.3% were classified as multi-drug resistant (MDR). Resistance rates of isolates in Mandrillus sphinx, Pan troglodytes, and humans were 50.6%, 57.7%, and 80.0%, respectively, with no significant statistical difference (p = 0.11). A single Extended-Spectrum Beta-Lactamase (ESBL) producing isolate was identified in the mandrill. Phylo-group analysis revealed the dominance of group A (50%), followed by groups B1, D, and C. Conclusions: Resistance profiles and phylo-group distribution among NHPs could suggest bacterial exchange and potential for cross-transmission of AMR within the shared environment. Full article
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15 pages, 296 KB  
Article
Hospital Cost Components and Predictors in Escherichia coli Bacteremia
by Tri Pudy Asmarawati, Fikri Sasongko Widyatama, Hari Basuki Notobroto, Erwin Astha Triyono, Nasronudin Nasronudin, Motoyuki Sugai and Kuntaman Kuntaman
Trop. Med. Infect. Dis. 2026, 11(5), 116; https://doi.org/10.3390/tropicalmed11050116 - 28 Apr 2026
Viewed by 315
Abstract
Background/Objectives: Escherichia coli bacteremia is a major cause of morbidity, mortality, and healthcare expenditure. The increasing prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) complicates management and resource utilization. This study aimed to identify clinical predictors of higher hospital [...] Read more.
Background/Objectives: Escherichia coli bacteremia is a major cause of morbidity, mortality, and healthcare expenditure. The increasing prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) complicates management and resource utilization. This study aimed to identify clinical predictors of higher hospital costs in E. coli bacteremia. Methods: We conducted a cross-sectional study of hospitalized patients with E. coli bacteremia in Surabaya, Indonesia (2022–2024). Hospital costs were categorized into bed costs, diagnostic costs, pharmacy costs, antibiotic costs, total costs, and daily costs. Costs were compared between ESBL and non-ESBL cases. Predictors of higher hospital costs were analyzed using generalized linear models with a Gamma distribution and log-link. Results: Among 209 patients, 131 (62.7%) had ESBL-producing E. coli. ESBL E. coli bacteremia was associated with significantly higher bed, diagnostic, pharmacy, total, and daily hospital costs than non-ESBL cases, while antibiotic costs were similar. ESBL E. coli bacteremia was associated with higher diagnostic and daily costs. High-care/ICU stay was the strongest predictor of increased costs. Pneumonia and infection source influenced cost components. Longer hospitalization increased total cost but reduced daily cost. Conclusions: Hospital costs in Escherichia coli bacteremia are driven by antimicrobial resistance, disease severity, and healthcare utilization. Targeted strategies such as antimicrobial stewardship and optimized critical care use are essential to reduce the economic burden. Full article
(This article belongs to the Section Infectious Diseases)
26 pages, 1923 KB  
Systematic Review
Systematic Review and Meta-Analysis of Extended-Spectrum Beta-Lactamase-Producing (ESBL) Escherichia coli in Food-Producing Animals and Animal Products in Nigeria
by Yusuf Yakubu, Mohammed Sani Gaddafi, Ummukulthum Lawal Hassan, Ibrahim Idris, Laura Felicioli and Kelvin Olutimilehin Jolayemi
Antibiotics 2026, 15(5), 432; https://doi.org/10.3390/antibiotics15050432 - 25 Apr 2026
Viewed by 464
Abstract
Background/Objectives: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are priority antimicrobial-resistant pathogens with significant implications for food safety and public health. Food-producing animals and their derived products represent a key interface for zoonotic transmission, yet prevalence data across Nigeria remain fragmented and unsynthesized. This [...] Read more.
Background/Objectives: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are priority antimicrobial-resistant pathogens with significant implications for food safety and public health. Food-producing animals and their derived products represent a key interface for zoonotic transmission, yet prevalence data across Nigeria remain fragmented and unsynthesized. This systematic review and meta-analysis assessed the prevalence, species distribution, geographical patterns, and detection methods of ESBL-producing E. coli in food-producing animals and animal-derived food products across Nigeria. Methods: A comprehensive search of PubMed, Web of Science, Scopus, and African journals online was conducted for studies published between January 2000 and January 2026, following PRISMA 2020 guidelines. Twenty eligible studies collectively analyzed 5104 samples, and 984 ESBL-positive isolates were included in the meta-analysis. Results: The overall pooled prevalence of ESBL-producing E. coli was 17.0% (95% CI: 13.0–21.0%; I2 = 89.4%). Subgroup analysis by animal species revealed the highest pooled prevalence among caprine (32.0%, 95% CI: 17.0–52.0%), bovine (24.0%, 95% CI: 17.0–33.0%), porcine (17.0%, 95% CI: 7.0–36.0%) and avian species (13.0%, 95% CI: 9.0–19.0%). Animal-derived food products showed a pooled prevalence of 19.0% (95% CI: 17.0–21.0%). Regional analysis showed the highest pooled prevalence in South-West (19.0%, 95% CI: 13.0–27.0%) and South-South (19.0%, 95% CI: 9.0–34.0%). Studies using combined culture and molecular methods reported higher pooled prevalence (19.0%, 95% CI: 14.0–25.0%) than culture alone (12.0%, 95% CI: 8.0–18.0%). However, the difference between subgroups was not statistically significant (test for subgroup differences: p = 0.0563). Conclusions: These findings confirm extensive ESBL-producing E. coli circulation in Nigerian food-producing animals and highlight critical gaps in antimicrobial stewardship, veterinary surveillance, and food safety infrastructure, underscoring the urgent need for coordinated One Health strategies to contain the spread of resistant strains through the food chain. 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 403
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)
13 pages, 918 KB  
Brief Report
Effectiveness and Sustainability of Water Chlorination in Public Healthcare Services in Guatemala
by Paulina Garzaro, Carmen Castillo, Natalie Fahsen, Lucas Santos, Joyce Lu, Christiana Hug, Matthew Lozier, Douglas R. Call, Celia Cordón-Rosales and Brooke M. Ramay
Trop. Med. Infect. Dis. 2026, 11(5), 111; https://doi.org/10.3390/tropicalmed11050111 - 23 Apr 2026
Viewed by 427
Abstract
Introduction: Healthcare-associated infections are a significant public health challenge, particularly in resource-limited settings. While hand hygiene is critical for infection prevention, contaminated water from hand hygiene stations (HHSs) in healthcare facilities (HCFs) may undermine infection control efforts. Chlorination can reduce microbial contamination in [...] Read more.
Introduction: Healthcare-associated infections are a significant public health challenge, particularly in resource-limited settings. While hand hygiene is critical for infection prevention, contaminated water from hand hygiene stations (HHSs) in healthcare facilities (HCFs) may undermine infection control efforts. Chlorination can reduce microbial contamination in HHSs, ensuring that water intended for hygiene does not become an infection source. Methods: Water quality was monitored before and after the installation of on-site chlorine dispensers (CDs) in water tanks and HHSs of HCFs in Quetzaltenango, Guatemala, to evaluate their effectiveness in improving water quality. Focus groups were conducted to develop action plan proposals to ensure the intervention’s sustainability. Results: Before the intervention, 75% of HHS water samples tested positive for total coliforms, with 50% testing positive for presumptive extended-spectrum beta-lactamase (ESBL)-producing total coliforms, while 20% were E. coli-positive, with 50% presumptive ESBL-producing E. coli. After installing CD, 1% of samples were coliform-positive over a six-month period. Focus groups identified resource limitations and political barriers and proposed solutions such as developing operational manuals, strengthening inter-institutional relationships, and forming alliances with external organizations. Conclusion: Localized chlorination was successfully implemented using a community participatory approach to improve water quality in resource-limited HCFs. These findings have important implications for infection prevention and control. Full article
(This article belongs to the Special Issue Epidemiology and Public Health in Tropical Regions of Central America)
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15 pages, 276 KB  
Review
Camel-Associated Antimicrobial Resistance: An Overlooked One Health Interface
by Arwa A. Faizo and Thamir A. Alandijany
Vet. Sci. 2026, 13(4), 383; https://doi.org/10.3390/vetsci13040383 - 15 Apr 2026
Viewed by 332
Abstract
Camel-associated antimicrobial resistance (AMR) is an underrecognized component of the One Health landscape, particularly in the Gulf Cooperation Council (GCC) and North Africa. Available evidence demonstrates the presence of clinically significant resistance mechanisms in camel populations, including extended-spectrum beta-lactamases, carbapenemases, colistin resistance genes, [...] Read more.
Camel-associated antimicrobial resistance (AMR) is an underrecognized component of the One Health landscape, particularly in the Gulf Cooperation Council (GCC) and North Africa. Available evidence demonstrates the presence of clinically significant resistance mechanisms in camel populations, including extended-spectrum beta-lactamases, carbapenemases, colistin resistance genes, and multidrug-resistant clones. Molecular similarities between camel and human isolates suggest potential cross-species transmission and highlight camels as possible reservoirs within interconnected human–animal–environment systems. Despite documented resistance patterns, camel production systems remain largely excluded from national AMR surveillance and stewardship frameworks. This gap reflects limited camel-specific data on antimicrobial usage and structural challenges related to pastoral mobility, cross-border trade, and emerging commercial intensification. Strengthening diagnostic capacity, implementing tailored antimicrobial stewardship strategies, and integrating camels into national AMR action plans are essential to mitigate potential public health risks. Proactive inclusion of camel systems within regional AMR governance frameworks is necessary to prevent further amplification of resistance. Full article
22 pages, 3206 KB  
Article
Characterization of Klebsiella Phages Isolated Against a Clinical Host with High Genome and Proteome Identity but Variable Tail Fibers
by Jessica M. Lewis, Daniel K. Arens, Nathan R. Zuniga and Julianne H. Grose
Viruses 2026, 18(4), 430; https://doi.org/10.3390/v18040430 - 1 Apr 2026
Viewed by 575
Abstract
The rate at which bacteria are gaining resistance to antibiotics is outpacing the discovery of new drugs. The rise of superbugs such as Carbapenem-resistant and Extended-Spectrum Beta-Lactamase Producing Enterobacteriaceae are leading to infections that are resistant to our last lines of defense. One [...] Read more.
The rate at which bacteria are gaining resistance to antibiotics is outpacing the discovery of new drugs. The rise of superbugs such as Carbapenem-resistant and Extended-Spectrum Beta-Lactamase Producing Enterobacteriaceae are leading to infections that are resistant to our last lines of defense. One of the most prolific genera of these bacteria is Klebsiella, which causes one third of Gram-negative infections. The need for alternative and companion treatments has never been greater. Bacteriophages are bacteria-infecting viruses with high specificity to their host. They show great promise as a potential treatment for antibiotic-resistant infections. Here, we describe the characterization of five closely related bacteriophages (ValerieMcCarty01–05) isolated against an antibiotic-resistant clinical strain of Klebsiella oxytoca, which is an emerging antimicrobial-resistant threat within the Klebsiella genus. These phages demonstrate high similarity at both the genomic and proteomic levels and share homology with other T4-like Enterobacterales phage. Two phages were further characterized through a mass spectrometry analysis of purified virions, identifying peptide spectrum matches for 40 proteins which appear to be virion proteins. In addition, the peptide spectrum matches for 39 hypothetical proteins suggest they are indeed proteins. Amino acid alignment revealed that the tail fibers display more variability than most of their genome, suggesting possible adaptive tail fiber gene shuffling. Despite this variability, these phages maintained broad but high specificity for Klebsiella species in this paper, including K. oxytoca, K. pneumoniae and K. aerogenes and several clinical Klebsiella isolates, with infectivity differences seen only in efficiency. This specificity for Klebsiella is consistent with the genus to which they belong (the Jiaodavirus, which contains only Klebsiella phages) and suggests they may be involved in the evolution of Klebsiella and be useful therapeutics. Full article
(This article belongs to the Special Issue Bacteriophage Diversity, 2nd Edition)
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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
Viewed by 833
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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17 pages, 325 KB  
Article
Prevalence and Antimicrobial Resistance Profiles of E. coli, P. mirabilis, and E. cloacae Complex Isolated from Dogs with Otitis Externa
by Ionela Popa, Ionica Iancu, Alexandru Gligor, Kalman Imre, Emil Tîrziu, Timea Bochiș, Călin Pop, Janos Degi, Andrei Ivan, Michael Dahma, Ana-Maria Plotuna, Sebastian Alexandru Popa, Marius Pentea, Viorel Herman and Ileana Nichita
Antibiotics 2026, 15(4), 343; https://doi.org/10.3390/antibiotics15040343 - 27 Mar 2026
Viewed by 570
Abstract
Background/Objectives: Antimicrobial resistance (AMR) in companion animals is an emerging public health threat due to zoonotic potential and limited therapeutic options. Dogs with otitis externa may harbor multidrug-resistant (MDR) bacteria, including Escherichia coli (E. coli), Proteus mirabilis (P. mirabilis), [...] Read more.
Background/Objectives: Antimicrobial resistance (AMR) in companion animals is an emerging public health threat due to zoonotic potential and limited therapeutic options. Dogs with otitis externa may harbor multidrug-resistant (MDR) bacteria, including Escherichia coli (E. coli), Proteus mirabilis (P. mirabilis), and Enterobacter cloacae complex (E. cloacae complex), some producing extended-spectrum beta-lactamase (ESBL) or AmpC β-lactamases. This study aimed to assess the prevalence, AMR patterns, MDR occurrence, β-lactamase production, and co-infection profiles of these pathogens in canine otitis externa. Methods: Ear canal samples were collected from 592 dogs presenting clinical signs of otitis externa, with one sample per dog included in the analysis. Samples were collected from veterinary clinics in Timiș County, Romania, from 2022 to 2025. Samples were cultured on blood agar and MacConkey agar, followed by biochemical testing and MALDI-TOF mass spectrometry for bacterial identification. Antimicrobial susceptibility testing against 15 agents across six classes was performed using the VITEK® 2 system. MDR and β-lactamase production (ESBL, AmpC) were determined according to CLSI 2018 veterinary guidelines. Co-isolation with bacterial and fungal species were recorded. Results: E. coli, P. mirabilis, and E. cloacae complex were isolated in 9.12%, 6.25%, and 1.2% of cases, respectively. E. coli exhibited the highest resistance to aminoglycosides (tobramycin 72.2%, gentamicin 61.1%) and full susceptibility to carbapenems. P. mirabilis showed the highest resistance to ampicillin (54%) and trimethoprim + sulfamethoxazole (46%), with complete susceptibility to carbapenems and fluoroquinolones. E. cloacae complex displayed universal resistance to cephalosporins but remained susceptible to non-cephalosporin β-lactams (piperacillin–tazobactam), carbapenems and aminoglycosides. MDR prevalence was 35.2% for E. coli, 18.9% for P. mirabilis, and 14.3% for the E. cloacae complex. ESBL production was detected in 13% of E. coli and 8.1% of P. mirabilis isolates, while all E. cloacae complex isolates were AmpC-positive. Co-isolations were common, primarily involving Staphylococcus pseudintermedius (S. pseudintermedius) and Malassezia pachydermatis (M. pachydermatis). Conclusions: MDR and β-lactamase-producing bacteria were identified in dogs with otitis externa, emphasizing the importance of routine antimicrobial susceptibility testing, targeted therapy based on local resistance profiles, and continuous AMR surveillance to prevent treatment failure and mitigate zoonotic risk. Full article
23 pages, 1321 KB  
Article
Antimicrobial Resistance and ESBL-Associated Predictors Among Uropathogens: A 2019–2024 Isolate-Level Study
by Raul-Lucian Ene, Roxana Popescu, Aurica Elisabeta Cobec, Daniela Puscasiu, Ileana-Adriana Ene, Daliborca Cristina Vlad, Ionut Marcel Cobec and Peter Seropian
Antibiotics 2026, 15(3), 323; https://doi.org/10.3390/antibiotics15030323 - 23 Mar 2026
Cited by 1 | Viewed by 975
Abstract
Background/Objectives: Urinary tract infections (UTIs) are among the most common bacterial infections and represent a major source of antimicrobial use. Increasing antimicrobial resistance among uropathogens, particularly the emergence of extended-spectrum beta-lactamase (ESBL)-producing organisms, complicates empiric treatment strategies. ESBL-producing organisms are clinically relevant because [...] Read more.
Background/Objectives: Urinary tract infections (UTIs) are among the most common bacterial infections and represent a major source of antimicrobial use. Increasing antimicrobial resistance among uropathogens, particularly the emergence of extended-spectrum beta-lactamase (ESBL)-producing organisms, complicates empiric treatment strategies. ESBL-producing organisms are clinically relevant because they are frequently associated with multidrug resistance and significantly limit empiric antimicrobial treatment options in urinary tract infections. The study period starting in 2019 was selected to reflect contemporary resistance patterns and to ensure consistency with the updated EUCAST antimicrobial susceptibility interpretation criteria introduced at that time. This study aimed to characterize antimicrobial resistance patterns among uropathogens isolated from lower UTIs and to identify independent predictors of antimicrobial resistance using isolate-level analyses. Methods: This retrospective observational study included 1470 patients and isolates with clinically suspected lower UTIs who underwent urine culture and antimicrobial susceptibility testing between 2019 and 2024 at a single clinical center. Antimicrobial susceptibility was interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria, and ESBL production was assessed among Gram-negative (GN) isolates. Multivariable generalized estimating equation (GEE) logistic regression models accounting for patient clustering were used to identify predictors of resistance. Results: A total of 1470 patients and isolates were included. Escherichia coli was the most frequent uropathogen (66.0%), followed by Klebsiella pneumoniae and Enterococcus faecalis. Among Gram-negative isolates, 17.3% were ESBL-positive. Resistance rates were highest for ciprofloxacin (35.4%) and trimethoprim/sulfamethoxazole (31.7%), while fosfomycin and nitrofurantoin retained high activity against E. coli. In multivariable analyses, ESBL production was the strongest independent predictor of resistance to several antimicrobials, including ciprofloxacin (aOR 9.83), amoxicillin/clavulanic acid (aOR 3.22), trimethoprim/sulfamethoxazole (aOR 2.89), and cefotaxime (aOR 1337). Pathogen identity was also independently associated with resistance. Conclusions: Antimicrobial resistance among uropathogens was heterogeneous and predominantly driven by pathogen identity and ESBL production. ESBL status emerged as the most consistent and powerful predictor of resistance across multiple antimicrobials, underscoring its clinical relevance for empiric treatment decisions and antimicrobial stewardship in urinary tract infections. Full article
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18 pages, 696 KB  
Article
Analysis of Antibiotic Consumption Trends and Pathogens’ Epidemiological Profile Within a Multidisciplinary Clinical Hospital from Romania
by Andreea-Roxana Ungureanu, Andreea-Alina Dumitru, Emma-Adriana Ozon, Andrei-Tudor Rogoz, Raluca-Narcisa Anghel, Elena Ciucu, Ancuța-Cătălina Fița and Nicoleta-Mirela Blebea
Antibiotics 2026, 15(3), 288; https://doi.org/10.3390/antibiotics15030288 - 12 Mar 2026
Viewed by 646
Abstract
Background/Objectives: In the broad and current context of antimicrobial resistance, antibiotic management and therapeutic surveillance are essential in hospitals. The present study (five-year retrospective, 2020–2024) aimed to analyze antibiotic consumption in relation to pathogens identified in a multidisciplinary hospital. Results: In terms of [...] Read more.
Background/Objectives: In the broad and current context of antimicrobial resistance, antibiotic management and therapeutic surveillance are essential in hospitals. The present study (five-year retrospective, 2020–2024) aimed to analyze antibiotic consumption in relation to pathogens identified in a multidisciplinary hospital. Results: In terms of antibiotic consumption (overall 2020–2024), although initially Watch antibiotics were predominantly used, a decrease was observed in favor of Access class antibiotics (sharply increase from 2022 to 2023 and maximum in 2024). For Reserve antibiotics, only slight annual fluctuations were observed, but there was an important reduction in colistin consumption. The most used were cephalosporins (cefazolin, cefuroxime and ceftriaxone), carbapenems (meropenem and ertapenem), vancomycin and linezolid. Regarding pathogens, the most notable were: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococcus spp., Pseudomonas aeruginosa. Among the ESKAPE bacteria, Acinetobacter baumannii was the least frequent in our samples. ESKAPE bacteria predominantly colonized specimens from the respiratory tract, digestive tract, skin and soft tissue. Resistant strains were observed, mainly Methicillin-resistant Staphylococcus aureus (MRSA) and Extended-Spectrum Beta-Lactamase (ESBL) Klebsiella spp., but no alarming increases in number were recorded in the analyzed period. Methods: The analysis was carried out using tools recommended by the World Health Organisation (Access Watch Reserve antibiotics classification (AWaRe); Bacterial Priority Pathogen List (BBPL); Defined Daily Dose (DDD)), Average Annual Percent Change (AAPC) calculation and ESKAPE classification (bacteria group: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.). Conclusions: Relatively stable trends in bacterial isolates and resistant strains over five years (2020–2024) are consistent with effective antimicrobial stewardship practices. Full article
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20 pages, 1688 KB  
Article
Overcoming Multidrug Resistance by Bacterial Efflux Pump Inhibitors in Clinical Escherichia coli Strains
by Nikoletta Szemerédi, Márta Nové, Danhui Heo, László Orosz, József Sóki and Gabriella Spengler
Antibiotics 2026, 15(3), 276; https://doi.org/10.3390/antibiotics15030276 - 9 Mar 2026
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Abstract
Background/Objectives: Antimicrobial resistance (AMR) is an escalating global threat driven by antibiotic misuse and bacterial adaptation. Efflux pumps are major contributors to multidrug resistance in Escherichia coli, as they expel antibiotics and reduce their intracellular activity. This study examined efflux-mediated resistance [...] Read more.
Background/Objectives: Antimicrobial resistance (AMR) is an escalating global threat driven by antibiotic misuse and bacterial adaptation. Efflux pumps are major contributors to multidrug resistance in Escherichia coli, as they expel antibiotics and reduce their intracellular activity. This study examined efflux-mediated resistance in extended-spectrum beta-lactamase (ESBL)-producing E. coli and evaluated the potential of several efflux pump inhibitors (EPIs)—promethazine (PMZ), thioridazine (TZ), carbonyl cyanide m-chlorophenyl hydrazine (CCCP), reserpine (RES), and phenyl-arginine-β-naphthylamide (PAβN)—as therapeutic adjuncts. Methods: Antibacterial and anti-biofilm activities of EPIs were tested using broth microdilution, real-time fluorimetry, and crystal violet assays, while ceftriaxone–PMZ interactions were assessed by checkerboard analysis. Results: TZ and CCCP showed strain-specific antibacterial activity, whereas PMZ, RES, and PAβN did not exert any effect. PMZ, TZ, and especially CCCP effectively inhibited efflux pump function, while RES and PAβN were less active. Biofilm inhibition varied between strains, with PMZ and TZ producing moderate reductions. We observed a quite weak synergism between ciprofloxacin, ceftriaxone, and PMZ; however, the result was not significant. Conclusions: Overall, the results highlight the central role of efflux pumps in ESBL-producing E. coli and indicate that EPIs can reverse resistance (e.g., PMZ) and exhibit potent anti-biofilm activity and show additive interactions with antibiotics. However, further studies are needed to optimize their safety, pharmacokinetics, and antibiotic pairing for potential clinical use. Full article
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14 pages, 767 KB  
Article
Epidemiology, Temporal Trends and Resistance Patterns of ESBL-Producing Non-Typhoidal Salmonella Isolated from Blood Cultures in Kisantu, DRC (2019–2022)
by Jules Mbuyamba, Gaelle Nkoji-Tunda, Daniel Vita, Laurence Ngara, Edmonde Bonebe, Marie-France Phoba, Anne-Sophie Heroes, Mohamadou Siribie, Birkneh Tilahun Tadesse, Glody-Nickel Mbaa, Florian Marks, Liselotte Hardy, Jan Jacobs, Lisette Mbuyi-Kalonji and Octavie Lunguya
Antibiotics 2026, 15(3), 271; https://doi.org/10.3390/antibiotics15030271 - 6 Mar 2026
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Abstract
Background: Antimicrobial resistance (AMR), particularly due to extended-spectrum beta-lactamases (ESBL), is a growing threat to public health in sub-Saharan Africa. This study investigates the prevalence, epidemiological characteristics, resistance patterns and resistance dynamic over time of ESBL-producing non-typhoidal Salmonella (NTS) bacteremia in Kisantu, Democratic [...] Read more.
Background: Antimicrobial resistance (AMR), particularly due to extended-spectrum beta-lactamases (ESBL), is a growing threat to public health in sub-Saharan Africa. This study investigates the prevalence, epidemiological characteristics, resistance patterns and resistance dynamic over time of ESBL-producing non-typhoidal Salmonella (NTS) bacteremia in Kisantu, Democratic Republic of Congo (DRC), from 2019 to 2022. Methods: A retrospective observational study used routine bloodstream infection data from the AMR network at Saint Luc Hospital in Kisantu. Blood cultures from suspected bacteremia cases were processed using standard microbiological techniques. Bacterial identification relied on biochemical reactions. Antibiotic susceptibility testing and ESBL-producing NTS detection were performed by disk diffusion following Clinical and Laboratory Standards Institute guidelines. Associations between ESBL production and patient characteristics (age, sex) were assessed using Pearson’s Chi-square test, and annual temporal trends in ESBL-producing NTS from 2019 to 2022 were analyzed by logistic regression using 2019 as the reference year. Results: Of the 19,430 blood cultures, 1681 NTS isolates were identified, and 1568 of these were screened for ESBL. ESBL prevalence was significantly associated with age (p = 0.007), peaking in children under 2 years, but not with sex (p = 0.570). Compared with 2019, the likelihood of isolating ESBL-producing NTS increased markedly through 2022, with adjusted probabilities rising from 58% to 87%, reflecting a strong upward temporal trend. High levels of extensively drug-resistant (94.1%) were observed. No carbapenem resistance was detected. Conclusions: ESBL-producing NTS bacteremia is rising in Kisantu, DRC, mainly affecting children under 2 years. Rising resistance to key antibiotics limits treatment options and highlights the need for strengthened AMR surveillance, optimized antibiotic use, and vaccination strategies. Full article
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