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18 pages, 1395 KiB  
Article
Finding the Missing IMP Gene: Overcoming the Imipenemase IMP Gene Drop-Out in Automated Molecular Testing for Carbapenem-Resistant Bacteria Circulating in Latin America
by Jose Arturo Molina-Mora, Ángel Rojas-Varela, Christopher Martínez-Arana, Lucia Portilla-Victor, Isaac Quirós-Fallas, Miryana Sánchez-Fonseca, Xavier Araya, Daniel Cascante-Serrano, Elvira Segura-Retana, Carlos Espinoza-Solís, María Jose Uribe-Calvo, Vanessa Villalobos-Alfaro, Heylin Estrada-Murillo, Stephanie Montoya-Madriz, Warren Madrigal, Mauricio Lizano, Stefany Lozada-Alvarado, Mariela Alvarado-Rodríguez, Mauricio Bolaños-Muñoz, Cristina García-Marín, Javier Alfaro-Camacho, Gian Carlo González-Carballo, Leana Quirós-Rojas, Joseph Sánchez-Fernández, Carolina Chaves-Ulate and Fernando García-Santamaríaadd Show full author list remove Hide full author list
Antibiotics 2025, 14(8), 772; https://doi.org/10.3390/antibiotics14080772 (registering DOI) - 30 Jul 2025
Viewed by 158
Abstract
Carbapenem resistance is considered one of the greatest current threats to public health, particularly in the management of infections in clinical settings. Carbapenem resistance in bacteria is mainly due to mechanisms such as the production of carbapenemases (such as the imipenemase IMP, or [...] Read more.
Carbapenem resistance is considered one of the greatest current threats to public health, particularly in the management of infections in clinical settings. Carbapenem resistance in bacteria is mainly due to mechanisms such as the production of carbapenemases (such as the imipenemase IMP, or other enzymes like VIM, NDM, and KPC), that can be detected by several laboratory tests, including immunochromatography and automated real-time PCR (qPCR). Methods: As part of local studies to monitor carbapenem-resistant bacteria in Costa Rica, two cases were initially identified with inconsistent IMP detection results. A possible gene drop-out in the automated qPCR test was suggested based on the negative result, contrasting with the positive result by immunochromatography and whole-genome sequencing. We hypothesized that molecular testing could be optimized through the development of tailored assays to improve the detection of IMP genes. Thus, using IMP gene sequences from the local isolates and regional sequences in databases, primers were redesigned to extend the detection of IMP alleles of regional relevance. Results: The tailored qPCR was applied to a local collection of 119 carbapenem-resistant isolates. The genomes of all 14 positive cases were sequenced, verifying the results of the custom qPCR, despite the negative results of the automated testing. Conclusions: Guided by whole-genome sequencing, it was possible to extend the molecular detection of IMP alleles circulating in Latin America using a tailored qPCR to overcome IMP gene drop-out and false-negative results in an automated qPCR. Full article
(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)
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13 pages, 513 KiB  
Article
Impact of Dietary Inputs on Carbapenem Resistance Gene Dynamics and Microbial Safety During Bioconversion of Agri-Food Waste and Anaerobic Digestate by Hermetia illucens Larvae
by Andrea Marcelli, Alessio Ilari, Vesna Milanović, Ester Foppa Pedretti, Kofi Armah Boakye-Yiadom, Federica Cardinali, Giorgia Rampanti, Andrea Osimani, Cristiana Garofalo and Lucia Aquilanti
Genes 2025, 16(8), 907; https://doi.org/10.3390/genes16080907 - 29 Jul 2025
Viewed by 119
Abstract
Background/Objectives: Hermetia illucens larvae can efficiently convert agri-food residues into high-protein biomass for animal feed and nutrient-rich frass for soil amendment. However, the potential spread of carbapenem resistance genes (CRGs), which confer resistance to last-resort carbapenem antibiotics, and Enterobacteriaceae, common carriers of [...] Read more.
Background/Objectives: Hermetia illucens larvae can efficiently convert agri-food residues into high-protein biomass for animal feed and nutrient-rich frass for soil amendment. However, the potential spread of carbapenem resistance genes (CRGs), which confer resistance to last-resort carbapenem antibiotics, and Enterobacteriaceae, common carriers of these genes and opportunistic pathogens, raises important safety concerns. This study aimed to assess the influence of different agri-food-based diets on Enterobacteriaceae loads and the CRG occurrence during the bioconversion process. Methods: Four experimental diets were formulated from agri-food residues and anaerobic digestate: Diet 1 (peas and chickpea waste), Diet 2 (peas and wheat waste), Diet 3 (onion and wheat waste), and Diet 4 (wheat waste and digestate). Enterobacteriaceae were quantified by viable counts, while five CRGs (blaKPC, blaNDM, blaOXA-48, blaVIM, and blaGES) were detected and quantified using quantitative PCRs (qPCRs). Analyses were performed on individual substrates, formulated diets, larvae (before and after bioconversion), and frass. Results: Plant-based diets sustained moderate Enterobacteriaceae loads. In contrast, the digestate-based diet led to a significant increase in Enterobacteriaceae in both the frass and mature larvae. CRGs were detected only in legume-based diets: blaVIM and blaGES were found in both mature larvae and frass, while blaOXA-48 and blaKPC were found exclusively in either larvae or frass. No CRGs were detected in onion- or digestate-based diets nor in young larvae or diet inputs. Conclusions: The findings suggest that the diet composition may influence the proliferation of Enterobacteriaceae and the persistence of CRGs. Careful substrate selection and process monitoring are essential to minimize antimicrobial resistance risks in insect-based bioconversion systems. Full article
(This article belongs to the Section Microbial Genetics and Genomics)
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73 pages, 19750 KiB  
Article
Transcriptomic Profiling of the Immune Response in Orthotopic Pancreatic Tumours Exposed to Combined Boiling Histotripsy and Oncolytic Reovirus Treatment
by Petros Mouratidis, Ricardo C. Ferreira, Selvakumar Anbalagan, Ritika Chauhan, Ian Rivens and Gail ter Haar
Pharmaceutics 2025, 17(8), 949; https://doi.org/10.3390/pharmaceutics17080949 - 22 Jul 2025
Viewed by 286
Abstract
Background: Boiling histotripsy (BH) uses high-amplitude, short-pulse focused ultrasound to disrupt tissue mechanically. Oncolytic virotherapy using reovirus has shown modest clinical benefit in pancreatic cancer patients. Here, reovirus and BH were used to treat pancreatic tumours, and their effects on the immune [...] Read more.
Background: Boiling histotripsy (BH) uses high-amplitude, short-pulse focused ultrasound to disrupt tissue mechanically. Oncolytic virotherapy using reovirus has shown modest clinical benefit in pancreatic cancer patients. Here, reovirus and BH were used to treat pancreatic tumours, and their effects on the immune transcriptome of these tumours were characterised. Methods: Orthotopic syngeneic murine pancreatic KPC tumours grown in immune-competent subjects, were allocated to control, reovirus, BH and combined BH and reovirus treatment groups. Acoustic cavitation was monitored using a passive broadband cavitation sensor. Treatment effects were assessed histologically with hematoxylin and eosin staining. Single-cell multi-omics combining whole-transcriptome analysis with the expression of surface-expressed immune proteins was used to assess the effects of treatments on tumoural leukocytes. Results: Acoustic cavitation was detected in all subjects exposed to BH, causing cellular disruption in tumours 6 h after treatment. Distinct cell clusters were identified in the pancreatic tumours 24 h post-treatment. These included neutrophils and cytotoxic T cells overexpressing genes associated with an N2-like and an exhaustion phenotype, respectively. Reovirus decreased macrophages, and BH decreased regulatory T cells compared to controls. The combined treatments increased neutrophils and the ratio of various immune cells to Treg. All treatments overexpressed genes associated with an innate immune response, while ultrasound treatments downregulated genes associated with the transporter associated with antigen processing (TAP) complex. Conclusions: Our results show that the combined BH and reovirus treatments maximise the overexpression of genes associated with the innate immune response compared to that seen with each individual treatment, and illustrate the anti-immune phenotype of key immune cells in the pancreatic tumour microenvironment. Full article
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26 pages, 477 KiB  
Review
Global Epidemiology and Antimicrobial Resistance of Klebsiella Pneumoniae Carbapenemase (KPC)-Producing Gram-Negative Clinical Isolates: A Review
by Matthew E. Falagas, Christina-Maria Asimotou, Maria Zidrou, Dimitrios S. Kontogiannis and Charalampos Filippou
Microorganisms 2025, 13(7), 1697; https://doi.org/10.3390/microorganisms13071697 - 19 Jul 2025
Viewed by 547
Abstract
Klebsiella pneumoniae carbapenemases (KPCs) are a group of class A β-lactamases of Gram-negative bacteria leading to difficult-to-treat infections. We evaluated the global epidemiology of KPC-producing Gram-negative clinical isolates. A systematic search of six databases (Cochrane Library, Embase, Google Scholar, PubMed, Scopus, and Web [...] Read more.
Klebsiella pneumoniae carbapenemases (KPCs) are a group of class A β-lactamases of Gram-negative bacteria leading to difficult-to-treat infections. We evaluated the global epidemiology of KPC-producing Gram-negative clinical isolates. A systematic search of six databases (Cochrane Library, Embase, Google Scholar, PubMed, Scopus, and Web of Science) was conducted. Extracted data were tabulated and evaluated. After screening 1993 articles, 119 were included in the study. The included studies originated from Asia (n = 49), Europe (n = 29), North America (n = 14), South America (n = 11), and Africa (n = 3); 13 studies were multicontinental. The most commonly reported KPC-producing species were Klebsiella pneumoniae (96 studies) and Escherichia coli (52 studies), followed by Enterobacter cloacae (31), Citrobacter spp. (24), Klebsiella oxytoca (23), Serratia spp. (15), Enterobacter spp. (15), Acinetobacter baumannii complex (13), Providencia spp. (11), Morganella spp. (11), Klebsiella aerogenes (9), Pseudomonas aeruginosa (8), Raoultella spp. (8), Proteus spp. (8), and Enterobacter aerogenes (6). Among the studies with specific blaKPC gene detection, 52/57 (91%) reported the isolation of blaKPC-2 and 26/57 (46%) reported blaKPC-3. The antimicrobial resistance of the studied KPC-producing isolates was the lowest for ceftazidime–avibactam (0–4%). Resistance to polymyxins, tigecycline, and trimethoprim–sulfamethoxazole in the evaluated studies was 4–80%, 0–73%, and 5.6–100%, respectively. Conclusions: The findings presented in this work indicate that KPC-producing Gram-negative bacteria have spread globally across all continents. Implementing proper infection control measures, antimicrobial stewardship programs, and enhanced surveillance is crucial. Full article
(This article belongs to the Special Issue ß-Lactamases, 3rd Edition)
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18 pages, 4199 KiB  
Article
Effects of Antibiotic Residues on Fecal Microbiota Composition and Antimicrobial Resistance Gene Profiles in Cattle from Northwestern China
by Wei He, Xiaoming Wang, Yuying Cao, Cong Liu, Zihui Qin, Yang Zuo, Yiming Li, Fang Tang, Jianjun Dai, Shaolin Wang and Feng Xue
Microorganisms 2025, 13(7), 1658; https://doi.org/10.3390/microorganisms13071658 - 14 Jul 2025
Viewed by 306
Abstract
Grazing is a free-range farming model commonly practiced in low-external-input agricultural systems. The widespread use of veterinary antibiotics in livestock farming has led to significant environmental accumulation of antibiotic residues and antibiotic resistance genes (ARGs), posing global health risks. This study investigated the [...] Read more.
Grazing is a free-range farming model commonly practiced in low-external-input agricultural systems. The widespread use of veterinary antibiotics in livestock farming has led to significant environmental accumulation of antibiotic residues and antibiotic resistance genes (ARGs), posing global health risks. This study investigated the antibiotic residues, bacterial community, ARG profiles, and mobile genetic elements (MGEs) in cattle feces from three provinces in western China (Ningxia, Xinjiang, and Inner Mongolia) under grazing modes. The HPLC-MS detection showed that the concentration of tetracycline antibiotics was the highest in all three provinces. Correlation analysis revealed a significant negative correlation between antibiotic residues and the diversity and population abundance of intestinal microbiota. However, the abundance of ARGs was directly proportional to antibiotic residues. Then, the Sankey analysis revealed that the ARGs in the cattle fecal samples were concentrated in 15 human pathogenic bacteria (HPB) species, with 9 of these species harboring multiple drug resistance genes. Metagenomic sequencing revealed that carbapenemase-resistant genes (blaKPC and blaVIM) were also present in considerable abundance, accounting for about 10% of the total ARGs detected in three provinces. Notably, Klebsiella pneumoniae strains carrying blaCTX-M-55 were detected, which had a possibility of IncFII plasmids harboring transposons and IS19, indicating the risk of horizontal transfer of ARGs. This study significantly advances the understanding of the impact of antibiotic residues on the fecal microbiota composition and ARG profiles in grazing cattle from northwestern China. Furthermore, it provides critical insights for the development of rational antibiotic usage strategies and comprehensive public health risk assessments. Full article
(This article belongs to the Section Antimicrobial Agents and Resistance)
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12 pages, 247 KiB  
Article
Restoring Control: Real-World Success with Imipenem–Relebactam in Critical MDR Infections—A Multicenter Observational Study
by Andrea Marino, Giuseppe Pipitone, Emmanuele Venanzi Rullo, Federica Cosentino, Rita Ippolito, Roberta Costa, Sara Bagarello, Ylenia Russotto, Chiara Iaria, Bruno Cacopardo and Giuseppe Nunnari
Pathogens 2025, 14(7), 685; https://doi.org/10.3390/pathogens14070685 - 11 Jul 2025
Viewed by 387
Abstract
Background: Multidrug-resistant (MDR) Gram-negative infections, particularly those caused by carbapenem-resistant Enterobacterales (CRE) and difficult-to-treat Pseudomonas aeruginosa (DTR-Pa), present a growing global healthcare challenge, especially in critically ill populations. Imipenem–relebactam (I/R), a novel β-lactam/β-lactamase inhibitor combination, has shown efficacy in clinical trials, but [...] Read more.
Background: Multidrug-resistant (MDR) Gram-negative infections, particularly those caused by carbapenem-resistant Enterobacterales (CRE) and difficult-to-treat Pseudomonas aeruginosa (DTR-Pa), present a growing global healthcare challenge, especially in critically ill populations. Imipenem–relebactam (I/R), a novel β-lactam/β-lactamase inhibitor combination, has shown efficacy in clinical trials, but real-world data remain limited. Methods: We conducted a multicenter, retrospective–prospective observational study across tertiary-care hospitals in Italy between January 2020 and May 2025. Adult patients (≥18 years) treated with I/R for ≥48 h for suspected or confirmed MDR Gram-negative infections were included. Primary endpoints were clinical success at the end of therapy and 30-day all-cause mortality. Secondary endpoints included microbiological eradication, recurrence, safety, and predictors of treatment failure. Statistical analysis involved descriptive methods and correlation analysis for mortality predictors. Results: Twenty-nine patients were included (median age 66 years; 58.6% ICU admission; 71.4% mechanical ventilation). Clinical success was achieved in 22/29 patients (75.9%), while 30-day mortality was 24.1% (7/29). The most common pathogen was Klebsiella pneumoniae (62.1%), with 41.4% of infections being polymicrobial. Microbiological eradication was confirmed in all the BSIs. Parenteral nutrition (p = 0.016), sepsis at presentation (p = 0.04), candidemia (p = 0.036), and arterial catheter use (p = 0.029) were significantly more frequent in non-survivors. Survivors showed significant reductions in CRP, PCT, and bilirubin at 48 h, while non-survivors did not. Parenteral nutrition (rho = 0.427, p = 0.023), sepsis (rho = 0.378, p = 0.043), and arterial catheter use (rho = 0.384, p = 0.04) were significantly correlated with mortality. Conclusions: In this Italian multicenter cohort of critically ill patients, imipenem–relebactam demonstrated high clinical success and acceptable mortality rates in the treatment of severe MDR Gram-negative infections, particularly those caused by KPC-producing K. pneumoniae. Early biomarker dynamics may aid in monitoring treatment response. Larger prospective studies are needed to confirm these findings and define optimal treatment strategies. Full article
11 pages, 239 KiB  
Article
Carbapenem-Resistant Enterobacteriaceae (CRE) in Children with Cancer: The Impact of Rapid Diagnostics and Targeted Colonization Strategies on Improving Outcomes
by Youssef Madney, Sally Mahfouz, Ahmed Bayoumi, Omayma Hassanain, Omneya Hassanain, Ahmed A. Sayed, Deena Jalal, Maryam Lotfi, May Tolba, Ghada A. Ziad, Mervat Elanany, Mohamed Hashem, Gehad Taha, Lobna Shalaby and Alaa Elhaddad
Microorganisms 2025, 13(7), 1627; https://doi.org/10.3390/microorganisms13071627 - 10 Jul 2025
Viewed by 964
Abstract
Carbapenem-resistant Enterobacteriaceae (CRE) pose an emerging threat, with a high mortality rate among children with cancer. This study aimed to evaluate the impact of routine rectal swab surveillance and rapid PCR-based detection of carbapenemase genes to facilitate the early initiation of appropriate treatment [...] Read more.
Carbapenem-resistant Enterobacteriaceae (CRE) pose an emerging threat, with a high mortality rate among children with cancer. This study aimed to evaluate the impact of routine rectal swab surveillance and rapid PCR-based detection of carbapenemase genes to facilitate the early initiation of appropriate treatment and assess its effects on outcomes. The study compared two groups of pediatric cancer patients with CRE bloodstream infections: a retrospective cohort of 254 patients from 2013 to 2017, and a prospective cohort of 186 patients from 2020 to 2022, following the implementation of these tools. A rapid diagnostic test in the prospective cohort resulted in the early initiation of proper antibiotics in 85% (165/186) of patients, compared to only 58% (147/254) in the retrospective group. This led to a decrease in the need for ICU admission related to sepsis from CRE and a significant reduction in the 30-day mortality rate (16% vs. 30%, p ≤ 0.01). Genotypic profiling revealed that class B carbapenemases were the most prevalent (69%), with the NDM type being identified in 67% of patients. OXA-48 and KPC enzymes were detected in 59% and 4% of patients, respectively. Multivariate analysis revealed that patients having Klebsiella pneumoniae, NDM genotype carbapenemases, presence of pneumonia, and septic shock requiring ICU admission were predictors of poor outcomes. Rapid diagnostics and targeted colonization lead to the appropriate use of targeted antibiotics, resulting in improved patient outcomes. Understanding carbapenemase-producing microorganisms and administering newer antibiotics may further reduce mortality and enhance treatment strategies for high-risk patients. Full article
(This article belongs to the Special Issue Antimicrobial Resistance: Challenges and Innovative Solutions)
11 pages, 1002 KiB  
Article
Unveiling the Evolution of MWC 728: Non-Conservative Mass Transfer in an FS CMa Binary
by Nadezhda L. Vaidman, Serik A. Khokhlov and Aldiyar T. Agishev
Galaxies 2025, 13(4), 78; https://doi.org/10.3390/galaxies13040078 - 7 Jul 2025
Viewed by 397
Abstract
We combine corrected Gaia DR3 astrometry with non-conservative MESA modelling to retrace the evolution of the FS-CMa binary MWC 728. The revised parallax sets the distance at d=1.2±0.1 kpc, leading—after Monte-Carlo error propagation—to luminosities of [...] Read more.
We combine corrected Gaia DR3 astrometry with non-conservative MESA modelling to retrace the evolution of the FS-CMa binary MWC 728. The revised parallax sets the distance at d=1.2±0.1 kpc, leading—after Monte-Carlo error propagation—to luminosities of log(L/L)acc=2.6±0.1 and log(L/L)don=1.5±0.1, corresponding to the accretor and donor, respectively. A fiducial binary track that starts with Mdon=3.6±0.1M, Macc=1.8±0.1M, and P0=21.0±0.2 d reproduces the observations provided the Roche-lobe overflow, which is moderately non-conservative: only 39% of the transferred mass is retained by the accretor, while the remainder leaves the system via (i) a fast isotropic wind from the donor (α=0.01), (ii) isotropic re-emission near the accretor (β=0.45), and (iii) outflow into a circumbinary torus (δ=0.15, lever arm γ=1.3). These channels remove sufficient angular momentum to expand the orbit to the observed Pobs=27.5±0.1 d while sustaining the dusty circumbinary outflow. At t223 Myr, the model matches every current observable: Mdon=1.30±0.05M, Macc=2.67±0.05M, mass ratio q=2.0±0.1, and an ongoing transfer rate of M˙(1±0.3)×106Myr1. MWC 728 thus serves as a benchmark intermediate-mass binary for testing how non-conservative outflows regulate angular-momentum loss and orbital growth. Full article
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12 pages, 1106 KiB  
Article
Antimicrobial Resistance and Virulence Determinants of Escherichia coli Isolates from Raw Milk of Dairy Cows with Subclinical Mastitis
by Ntelekwane George Khasapane, Olga de Smidt, Kgaugelo Edward Lekota, Jane Nkhebenyane, Oriel Thekisoe and Tsepo Ramatla
Animals 2025, 15(13), 1980; https://doi.org/10.3390/ani15131980 - 5 Jul 2025
Viewed by 278
Abstract
Subclinical mastitis (SCM) is a stealthy but devastating challenge in the dairy industry, leading to economic losses and hindering efforts to achieve milk self-sufficiency. This study investigated the prevalence of SCM, antimicrobial resistance, and virulence profiles of Escherichia coli. A total of [...] Read more.
Subclinical mastitis (SCM) is a stealthy but devastating challenge in the dairy industry, leading to economic losses and hindering efforts to achieve milk self-sufficiency. This study investigated the prevalence of SCM, antimicrobial resistance, and virulence profiles of Escherichia coli. A total of 174 milk samples were analyzed using the California mastitis test (CMT), somatic cell counts (SCCs), bacteriological culture, MALDI-TOF MS, and polymerase chain reaction (PCR). The findings revealed that the SCM prevalence was 68/174 (39.08%) based on CMT and SCC. Among SCM-positive samples, 60/68 (88.23%) were identified as E. coli, confirmed by MALDI-TOF MS and PCR assay. The most frequently detected serogroups were 0113 (11.6%) and 0113 (3.3%). Additionally, the genes for Stx1 and Stx2 were also detected in nine (15%) and one (1.7%), respectively. Antimicrobial susceptibility tests showed widespread resistance, with E. coli isolates demonstrating resistance to penicillin in 43 (71.6%), followed by ciprofloxacin in 42 (70%) and gentamicin in 18 (30%). A larger proportion of the E. coli strains (100%) harbored the blaVIM gene, while 23 (38.3%), 20%, 20%, and 1.47% contained blaKPC, blaNMD, suli1, and msrA. Thirty (50%) isolates were considered multidrug-resistant (MDR). These findings underscore the urgent need for enhanced surveillance and antibiotic stewardship in dairy farming. The presence of MDR E. coli in SCM poses a dual threat of potential transmission to humans and treatment failures in mastitis management. This study highlights the importance of proactive control strategies to mitigate the spread of antimicrobial resistance in livestock and beyond. Full article
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11 pages, 4880 KiB  
Communication
The Nosocomial Transmission of Carbapenem-Resistant Gram-Negative Bacteria in a Hospital in Baoding City, China
by Shengnan Liao, Wei Su, Tianjiao Li, Zeyang Li, Zihan Pei, Jie Zhang and Wenjuan Yin
Microbiol. Res. 2025, 16(7), 147; https://doi.org/10.3390/microbiolres16070147 - 2 Jul 2025
Viewed by 282
Abstract
Background: The global rise of multidrug-resistant Gram-negative bacteria, particularly non-fermenting species and carbapenemase-producing Enterobacteriaceae, poses a significant challenge to hospital infection control. Methods: In this study, a total of 89 Acinetobacter spp. isolates, 14 Pseudomonas aeruginosa, and 14 carbapenem-resistant Enterobacteriaceae isolates were [...] Read more.
Background: The global rise of multidrug-resistant Gram-negative bacteria, particularly non-fermenting species and carbapenemase-producing Enterobacteriaceae, poses a significant challenge to hospital infection control. Methods: In this study, a total of 89 Acinetobacter spp. isolates, 14 Pseudomonas aeruginosa, and 14 carbapenem-resistant Enterobacteriaceae isolates were collected from patients in a tertiary hospital. Whole-genome sequencing and antimicrobial susceptibility testing were conducted. Resistance mechanisms and evolutionary relationships were analyzed using phylogenetic analysis and genetic context mapping. Results: Among the non-fermenting isolates, A. baumannii exhibited high resistance to carbapenems, clustering into distinct clonal groups enriched with genes associated with biofilm formation and virulence genes. P. aeruginosa isolates harbored fewer resistance genes but carried notable mutations in the efflux pump systems and the oprD gene. In Enterobacteriaceae, four blaNDM alleles were identified within a conservative structural sequence, while blaKPC-2 was located in a non-Tn4401 structure flanked by IS481- and IS1182-like insertion sequences. Phylogenetic analysis revealed that blaNDM-positive E. coli strains were closely related to susceptible lineages, indicating horizontal gene transfer. Conversely, K. pneumoniae isolates harboring blaKPC-2 formed a tight clonal cluster, suggesting clonal expansion. Conclusions: The study reveals distinct transmission patterns between resistance genes: horizontal dissemination of blaNDM and clonal expansion of blaKPC-2 in K. pneumoniae. These findings emphasize the need for resistance-gene-specific genomic surveillance and infection control strategies to prevent further nosocomial dissemination. Full article
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15 pages, 916 KiB  
Article
Carbapenem-Resistant Gram-Negative Bacteria in Hospitalized Patients: A Five-Year Surveillance in Italy
by Marcello Guido, Antonella Zizza, Raffaella Sedile, Milva Nuzzo, Laura Isabella Lupo and Pierfrancesco Grima
Infect. Dis. Rep. 2025, 17(4), 76; https://doi.org/10.3390/idr17040076 - 2 Jul 2025
Viewed by 306
Abstract
Background/Objectives: Antibiotic resistance is a significant and escalating challenge that limits available therapeutic options. This issue is further exacerbated by the decreasing number of new antibiotics being developed. Our study aims to describe the epidemiology and pattern of antibiotic resistance in Gram-negative [...] Read more.
Background/Objectives: Antibiotic resistance is a significant and escalating challenge that limits available therapeutic options. This issue is further exacerbated by the decreasing number of new antibiotics being developed. Our study aims to describe the epidemiology and pattern of antibiotic resistance in Gram-negative infections isolated from a cohort of hospitalized patients and to analyze the distribution of infections within the hospital setting. Methods: A retrospective study was conducted on all patients admitted to Vito Fazzi Hospital in Lecce, Italy, who required an infectious disease consultation due to the isolation of Gram-negative bacteria from 1 January 2018 to 31 December 2022. Results: During the study period, 402 isolates obtained from 382 patients (240 men and 142 women) with infections caused by Gram-negative bacteria were identified. Among these isolated, 226 exhibited multidrug resistance, defined as resistance to at least one antimicrobial agent from three or more different classes. In 2018, the percentage of multidrug-resistant isolates peaked at 87.6%, before decreasing to the lowest level (66.2%) in 2021. Overall, of the 402 isolates, 154 (38.3%) displayed resistance to carbapenems, while 73 (18.1%) were resistant to extended-spectrum beta-lactamases (ESBLs). Among the resistant microorganisms, Klebsiella pneumoniae showed the highest resistance to carbapenems, accounting for 85.2% of all resistant strains. Escherichia coli exhibited the greatest resistance to ESBLs, with a rate of 86.7%. Among carbapenem-resistant K. pneumoniae isolates, the following resistance rates were observed: KPC-1 at 98.2%, IMP-1 at 0.9%, VIM-1 at 0.9%, and NDM-1 at 0.9%. Conclusions: Patients with infections caused by multidrug-resistant bacteria have limited treatment options and are therefore at an increased risk of death, complications, and longer hospital stays. Rapid diagnostic techniques and antimicrobial stewardship programs—especially for ESBLs and carbapenemases—can significantly shorten the time needed to identify the infection and initiate appropriate antimicrobial therapy compared to traditional methods. Additionally, enhancing surveillance of antimicrobial resistance within populations is crucial to address this emerging public health challenge. Full article
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12 pages, 1312 KiB  
Article
Antimicrobial Resistance in the Aconcagua River, Chile: Prevalence and Characterization of Resistant Bacteria in a Watershed Under High Anthropogenic Contamination Pressure
by Nicolás González-Rojas, Diego Lira-Velásquez, Richard Covarrubia-López, Johan Plaza-Sepúlveda, José M. Munita, Mauricio J. Carter and Jorge Olivares-Pacheco
Antibiotics 2025, 14(7), 669; https://doi.org/10.3390/antibiotics14070669 - 2 Jul 2025
Viewed by 441
Abstract
Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for [...] Read more.
Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for AMR evolution and transmission. In Chile, the Aconcagua River—subject to multiple anthropogenic pressures—offers a representative model for studying the environmental dimensions of AMR. Methods: Thirteen surface water samples were collected along the Aconcagua River basin in a single-day campaign to avoid temporal bias. Samples were filtered through 0.22 μm membranes and cultured on MacConkey agar, either unsupplemented or supplemented with ceftazidime (CAZ) or ciprofloxacin (CIP). Isolates were purified and identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was evaluated using the Kirby–Bauer disk diffusion method in accordance with CLSI guidelines. Carbapenemase activity was assessed using the Blue-Carba test, and PCR was employed for the detection of the blaVIM, blaKPC, blaNDM, and blaIMP genes. Results: A total of 104 bacterial morphotypes were isolated; 80 were identified at the species level, 5 were identified at the genus level, and 19 could not be taxonomically assigned using MALDI-TOF. Pseudomonas (40 isolates) and Aeromonas (25) were the predominant genera. No growth was observed on CIP plates, while 24 isolates were recovered from CAZ-supplemented media, 87.5% of which were resistant to aztreonam. Five isolates exhibited resistance to carbapenems; two tested positive for carbapenemase activity and carried the blaVIM gene. Conclusions: Our results confirm the presence of clinically significant resistance mechanisms, including blaVIM, in environmental Pseudomonas spp. from the Aconcagua River. These findings highlight the need for environmental AMR surveillance and reinforce the importance of adopting a One Health approach to antimicrobial stewardship and wastewater regulation. Full article
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23 pages, 1347 KiB  
Article
Antibiotic Resistance, Virulence Genes, and Molecular Diversity of Clinical Klebsiella pneumoniae Isolates from Patients of District Hospital in Central Poland
by Barbara Kot, Małgorzata Witeska, Piotr Szweda, Małgorzata Piechota, Elżbieta Kondera, Elżbieta Horoszewicz, Izabela Balak, Ahmer Bin Hafeez and Alicja Synowiec
Pathogens 2025, 14(7), 648; https://doi.org/10.3390/pathogens14070648 - 30 Jun 2025
Viewed by 311
Abstract
In hospital environments, pathogenic bacteria spread easily and acquire virulence and antibiotic resistance genes. The aim of the study was an evaluation of the genetic diversity of 109 K. pneumoniae isolates recovered from patients of a district hospital in central Poland. The frequencies [...] Read more.
In hospital environments, pathogenic bacteria spread easily and acquire virulence and antibiotic resistance genes. The aim of the study was an evaluation of the genetic diversity of 109 K. pneumoniae isolates recovered from patients of a district hospital in central Poland. The frequencies of genes coding for β-lactamases, efflux pumps, and virulence factors were determined. Genotyping of the isolates was performed with ERIC (Enterobacterial Repetitive Intergenic Consensus) and REP (Repetitive Element Sequence Based) PCR techniques, with 21 and 19 genotypes being identified, respectively. The blaSHV-1 (92.7%), blaCTX-M group 1 (83.5%), blaTEM-1 (28.4%), blaNDM-1 (16.5%), blaVEB-1 (11.0%), blaCTX-M group 9 (3.7%), blaKPC (1.8%), blaIMP, blaOXA-48, blaCTX-M group 2, blaCTX-M groups 8, and 25/26 (0% each) and efflux pumps: AcrAB (100%), tolC (93.6%), and mdtk (60.5%), and virulence genes coding: urease subunit ureA (94.5%) endotoxins wabG (92.7%) and uge (64.2%), and siderophore iucB (3.7%) were detected. The blaSHV-1, blaCTX-M group 1, mdtk, tolC, AcrAB (16.5%); blaSHV-1, blaCTX-M group 1, tolC, AcrAB (15.6%), and blaSHV-1, blaCTX-M group 1, blaNDM-1, mdtk, tolC, AcrAB (11.9%) were the most common resistance patterns. The distribution of resistance and virulence genes varied more between hospital wards than between different clinical materials. Hospital’s antibiotic-resistant and virulent K. pneumoniae, able to spread among humans, animals, and in the environment, pose a significant threat to public health. Full article
(This article belongs to the Section Bacterial Pathogens)
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15 pages, 433 KiB  
Article
In Vitro Activity of Novel β-Lactam/β-Lactamase Inhibitors Against Carbapenem-Resistant Pseudomonas aeruginosa and Enterobacterales in Korea
by Seulgi Moon, Jongyoun Yi, Mee Kyung Ko, Yong Ki Sim and Kye-Hyung Kim
Antibiotics 2025, 14(7), 649; https://doi.org/10.3390/antibiotics14070649 - 26 Jun 2025
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Abstract
Background/Objectives: Carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are challenging multidrug-resistant pathogens. This study evaluated the in vitro susceptibility of CRE and CRPA blood isolates from Korea to novel β-lactam/β-lactamase inhibitor combinations: ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/cilastatin/relebactam (IMR), and meropenem/vaborbactam (MEV). Methods: [...] Read more.
Background/Objectives: Carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are challenging multidrug-resistant pathogens. This study evaluated the in vitro susceptibility of CRE and CRPA blood isolates from Korea to novel β-lactam/β-lactamase inhibitor combinations: ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/cilastatin/relebactam (IMR), and meropenem/vaborbactam (MEV). Methods: Blood isolates of CRE (n = 55) and CRPA (n = 65) collected between September 2017 and September 2022 in a Korean tertiary hospital were included. Carbapenemase production was determined using phenotypic and molecular methods. In vitro susceptibility to C/T, CZA, IMR, and MEV was determined primarily by broth microdilution using current CLSI/EUCAST breakpoints. Clinical characteristics and in-hospital mortality were retrospectively reviewed. Results: Among non-carbapenemase-producing (non-CP) CRPA isolates (n = 47), susceptibility rates were 83.0% to C/T and 70.2% to CZA. For KPC-producing CRE isolates (n = 28), susceptibility rates were high to CZA (92.9%), IMR (82.1%), and MEV (96.4%). However, non-CP CRE isolates (n = 22) showed low susceptibility to C/T (18.2%) but high susceptibility to CZA (100%), IMR (81.8%), and MEV (95.5%). CRE infections were associated with higher rates of hematologic malignancy, immunosuppression, and in-hospital mortality (63.6% vs. 18.5% for CRPA, p < 0.001). Conclusions: The susceptibility of CRE and CRPA to novel β-lactam/β-lactamase inhibitors varies significantly by species and carbapenemase production. CZA, IMR, and MEV showed promising activity against KPC-producing CRE. These findings can inform empirical therapy and stewardship efforts in Korea. Full article
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21 pages, 2764 KiB  
Article
First Report of Stenotrophomonas maltophilia from Canine Dermatological Infections: Unravelling Its Antimicrobial Resistance, Biofilm Formation, and Virulence Traits
by Ria Rajeev, Porteen Kannan, Sureshkannan Sundaram, Sandhya Bhavani Mohan, Sivachandiran Radjendirane, Chaudhary Jeetendrakumar Harnathbhai, Anbazhagan Subbaiyan, Viswanathan Naveenkumar, Nithya Quintoil Mohanadasse, Wilfred Ruban Savariraj, Charley A. Cull and Raghavendra G. Amachawadi
Antibiotics 2025, 14(7), 639; https://doi.org/10.3390/antibiotics14070639 - 23 Jun 2025
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Abstract
Background/Objectives: The present study was aimed at documenting S. maltophilia occurrence in dogs with skin ailments, investigating its virulence, biofilm-forming ability, antimicrobial susceptibility, and zoonotic potential to inform preventive and therapeutic strategies against multidrug resistant S. maltophilia infections. Methods: Skin swabs [...] Read more.
Background/Objectives: The present study was aimed at documenting S. maltophilia occurrence in dogs with skin ailments, investigating its virulence, biofilm-forming ability, antimicrobial susceptibility, and zoonotic potential to inform preventive and therapeutic strategies against multidrug resistant S. maltophilia infections. Methods: Skin swabs (n = 300) were collected from dogs with dermatological ailments. Isolation was performed using selective media and confirmed with molecular methods, validated by MALDI Biotyper. Antimicrobial susceptibility testing and efflux activity assessment were conducted. Resistance genes related to sulfonamides, quinolones, and β-lactams were screened. Virulence was assessed by biofilm formation, motility, and virulence gene profiling. Results: In total, 15 S. maltophilia (5%) isolates were identified. All 15 isolates were susceptible to trimethoprim-sulfamethoxazole, enrofloxacin, gatifloxacin, levofloxacin, minocycline, and tigecycline, but resistant to cefpodoxime and aztreonam. The following resistance genes qnr (93.3%), blaOXA-48 (46.7%), blaKPC (33.3%), blaNDM (33.3%), blaCTX-M (20%), blaSHV (20%), and blaTEM (6.7%) were detected. All 15 isolates displayed high efflux activity. Overall, 9 isolates (60%) were strong biofilm producers, and 6 (40%) were moderate. Virulence genes such as virB, motA, rmlA, and fliC were present in all 15 isolates, with others varying in frequency. All isolates exhibited swimming motility. Heat map clustering showed diverse profiles, with no identical isolate patterns. Correlation analysis indicated positive associations between several antimicrobial resistance and virulence genes. Conclusions: This study underscores the zoonotic potential of S. maltophilia from dogs, advocating for a One Health approach to mitigate infection risks and limit the spread of virulent multidrug resistant pathogens. Full article
(This article belongs to the Special Issue Antimicrobial Resistance and Infections in Veterinary Settings)
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