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15 pages, 3534 KiB  
Article
Detection and Genomic Characteristics of NDM-19- and QnrS11-Producing O101:H5 Escherichia coli Strain Phylogroup A: ST167 from a Poultry Farm in Egypt
by Ahmed M. Soliman, Hazem Ramadan, Toshi Shimamoto, Tetsuya Komatsu, Fumito Maruyama and Tadashi Shimamoto
Microorganisms 2025, 13(8), 1769; https://doi.org/10.3390/microorganisms13081769 - 29 Jul 2025
Viewed by 322
Abstract
This study describes the first complete genomic sequence of an NDM-19 and QnrS11-producing multidrug-resistant (MDR) Escherichia coli isolate collected from a fecal swab from a poultry farm in 2019 in Egypt. The blaNDM-19 was identified by PCR screening and DNA sequencing. The [...] Read more.
This study describes the first complete genomic sequence of an NDM-19 and QnrS11-producing multidrug-resistant (MDR) Escherichia coli isolate collected from a fecal swab from a poultry farm in 2019 in Egypt. The blaNDM-19 was identified by PCR screening and DNA sequencing. The isolate was then subjected to antimicrobial susceptibility testing, conjugation and transformation experiments, and complete genome sequencing. The chromosome of strain M2-13-1 measures 4,738,278 bp and encodes 4557 predicted genes, with an average G + C content of 50.8%. M2-13-1 is classified under ST167, serotype O101:H5, phylogroup A, and shows an MDR phenotype, having minimum inhibitory concentrations (MICs) of 64 mg/L for both meropenem and doripenem. The genes blaNDM-19 and qnrS11 are present on 49,816 bp IncX3 and 113,285 bp IncFII: IncFIB plasmids, respectively. M2-13-1 harbors genes that impart resistance to sulfonamides (sul1), trimethoprim (dfrA14), β-lactams (blaTEM-1B), aminoglycosides (aph(6)-Id, aph(3′)-Ia, aph(3″)-Ib, aac(3)-IV, and aph(4)-Ia), tetracycline (tet(A)), and chloramphenicol (floR). It was susceptible to aztreonam, colistin, fosfomycin, and tigecycline. The genetic context surrounding blaNDM-19 includes ISAba125-IS5-blaNDM-19-bleMBL-trpF-hp1-hp2-IS26. Hierarchical clustering of the core genome MLST (HierCC) indicated M2-13-1 clusters with global ST167 E. coli lineages, showing HC levels of 100 (HC100) core genome allelic differences. Plasmids of the IncX3 group and the insertion sequence (ISAba125) are critical vehicles for the dissemination of blaNDM and its related variants. To our knowledge, this is the first genomic report of a blaNDM-19/IncX3-carrying E. coli isolate of animal origin globally. Full article
(This article belongs to the Special Issue Gut Microbiota of Food Animal)
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19 pages, 2130 KiB  
Article
Isolation of ESBL-Producing Enterobacteriaceae in Food of Animal and Plant Origin: Genomic Analysis and Implications for Food Safety
by Rosa Fraccalvieri, Stefano Castellana, Angelica Bianco, Laura Maria Difato, Loredana Capozzi, Laura Del Sambro, Adelia Donatiello, Domenico Pugliese, Maria Tempesta, Antonio Parisi and Marta Caruso
Microorganisms 2025, 13(8), 1770; https://doi.org/10.3390/microorganisms13081770 - 29 Jul 2025
Viewed by 234
Abstract
Background: The spread of ESBL-producing Enterobacteriaceae (ESBL-PE) strains in food poses a potential risk to human health. The aim of the study was to determine the occurrence of ESBL-PE and to investigate their distribution on foods. Methods: A total of 1000 food [...] Read more.
Background: The spread of ESBL-producing Enterobacteriaceae (ESBL-PE) strains in food poses a potential risk to human health. The aim of the study was to determine the occurrence of ESBL-PE and to investigate their distribution on foods. Methods: A total of 1000 food samples, including both raw and ready-to-eat products, was analyzed for the presence of ESBL-producing Enterobacteriaceae using chromogenic selective agar. Antibiotic resistance in the isolated strains was assessed using conventional methods, while whole-genome sequencing was employed to predict antimicrobial resistance and virulence genes. Results: The overall occurrence of ESBL-PE strains was 2.8%, with the highest contamination in raw meat samples (10%). A total of 31 multidrug-resistant (MDR) strains was isolated, mainly Escherichia coli, followed by Klebsiella pneumoniae, Salmonella enterica, and Enterobacter hormaechei. All strains exhibited high levels of resistance to at least four different β-lactam antibiotics, as well as to other antimicrobial classes including sulfonamides, tetracyclines, aminoglycosides, and quinolones. Whole-genome sequencing identified 63 antimicrobial resistance genes, with blaCTX-M being the most prevalent ESBL gene. Twenty-eight (90%) isolates carried Inc plasmids, known vectors of multiple antimicrobial resistance genes, including those associated with ESBLs. Furthermore, several virulence genes were identified. Conclusions: The contamination of food with ESBL-PE represents a potential public health risk, underscoring the importance of the implementation of genomic surveillance to monitor and control the spread of antimicrobial resistance. Full article
(This article belongs to the Special Issue Food Microorganisms and Genomics, 2nd Edition)
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20 pages, 2552 KiB  
Article
Environmental Dispersion of Multiresistant Enterobacteriaceae in Aquatic Ecosystems in an Area of Spain with a High Density of Pig Farming
by Javier Díez de los Ríos, Noemí Párraga-Niño, María Navarro, Judit Serra-Pladevall, Anna Vilamala, Elisenda Arqué, María Baldà, Tamar Nerea Blanco, Luisa Pedro-Botet, Óscar Mascaró and Esteban Reynaga
Antibiotics 2025, 14(8), 753; https://doi.org/10.3390/antibiotics14080753 - 25 Jul 2025
Viewed by 273
Abstract
Background: This study aimed to (a) assess the prevalence of multidrug-resistant (MDR) Enterobacteriaceae in the waters of two rivers and wastewater treatment plants (WWTPs) in a region of Catalonia, Spain; (b) genetically characterize the MDR strains; and (c) compare extended-spectrum β-lactamase (ESBL)-producing [...] Read more.
Background: This study aimed to (a) assess the prevalence of multidrug-resistant (MDR) Enterobacteriaceae in the waters of two rivers and wastewater treatment plants (WWTPs) in a region of Catalonia, Spain; (b) genetically characterize the MDR strains; and (c) compare extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates from environmental and human sources. Methods: A total of 62 samples were collected from the influent and effluent of 31 WWTPs and 29 river water samples from 11 sites. Simultaneously, 382 hospitalized patients were screened for MDR Enterobacteriaceae using rectal swabs. All isolates underwent antibiotic susceptibility testing and whole-genome sequencing. Results: MDR Enterobacteriaceae were detected in 48.4% of WWTP samples, with 18.5% ESBL-producing E. coli and 1.5% (one sample) OXA-48-producing K. pneumoniae in influents, and 12.8% ESBL-producing E. coli in effluents. In river waters, 5.6% of samples contained ESBL-producing E. coli and 1.4% (1 sample) contained VIM-producing Enterobacter cloacae complex strains. Among patients, 10.2% (39/382) carried MDR Gram-negative bacilli, of which 66.7% were ESBL-producing E. coli. In aquatic ecosystems E. coli ST131 (13.3%) and ST162 (13.3%) were the most common strains, while in humans the common were E. coli ST131 (33.3%), ST69 (11.1%) and ST410 (7.4%) in humans. The most frequent environmental antibiotic resistance genes (ARG) were blaCTX-M-15 (24%) and blaTEM-1B (20%), while the most common ARGs were blaTEM-1B (20.4%), blaCTX-M15 (18.4%) and blaCTX-M-27 (14.3%). IncF plasmids were predominant in environmental and human strains. Conclusions: ESBL-producing E. coli and carbapenemase-producing Enterobacteriaceae are present in aquatic environments in the region. Phylogenetic similarities between environmental and clinical strains suggest a possible similar origin. Further studies are necessary to clarify transmission routes and environmental impact. Full article
(This article belongs to the Special Issue A One Health Approach to Antimicrobial Resistance, 2nd Edition)
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11 pages, 775 KiB  
Article
Whole Genome Sequencing of Klebsiella variicola Strains Isolated from Patients with Cancer
by Alicja Sękowska, Andrés Carrazco-Montalvo and Yulian Konechnyi
Antibiotics 2025, 14(8), 735; https://doi.org/10.3390/antibiotics14080735 - 22 Jul 2025
Viewed by 387
Abstract
Background: Klebsiella variicola is a Gram-negative, capsulated, nonmotile, facultative anaerobic rod. It is one of the species belonging to the K. pneumoniae complex. The objective of this study was to gain insights into the antimicrobial resistance and virulence of K. variicola [...] Read more.
Background: Klebsiella variicola is a Gram-negative, capsulated, nonmotile, facultative anaerobic rod. It is one of the species belonging to the K. pneumoniae complex. The objective of this study was to gain insights into the antimicrobial resistance and virulence of K. variicola strains isolated from clinical samples from oncologic patients. Methods: Strain identification was performed using a mass spectrometry method. Whole genome sequencing was conducted for all analyzed strains. Antimicrobial susceptibility was determined using an automated method. The presence of antimicrobial resistance mechanisms and genes encoding extended-spectrum beta-lactamases (ESBL) was assessed using the double-disc synergy test and genotypic methods. Results: All isolates were identified as K. variicola using mass spectrometry and whole genome sequencing (WGS). All isolates were ESBL-positive, and two of them harbored the blaCTX-M-15 gene. In our study, the blaLEN-17 gene was detected in all strains. Genome sequence analysis of the K. variicola isolates revealed the presence of virulence factor genes, including entAB, fepC, ompA, ykgK, and yagWXYZ. Two different plasmids, IncFIB(K) and IncFII, were identified in all of the analyzed K. variicola strains. The detected virulence factors suggest the ability of the bacteria to survive in the environment and infect host cells. All isolates demonstrated in vitro susceptibility to carbapenems. Conclusions: Further studies are needed to confirm whether multidrug-resistant K. variicola strains represent an important pathogen in infections among oncologic patients. Full article
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16 pages, 1988 KiB  
Article
Epidemiological Surveillance, Variability, and Evolution of Isolates Belonging to the Spanish Clone of the 4,[5],12:i:- Monophasic Variant of Salmonella enterica Serovar Typhimurium
by Xenia Vázquez, Patricia García, Javier Fernández, Víctor Ladero, Carlos Rodríguez-Lucas, Jürgen J. Heinisch, Rosaura Rodicio and M. Rosario Rodicio
Antibiotics 2025, 14(7), 711; https://doi.org/10.3390/antibiotics14070711 - 16 Jul 2025
Viewed by 282
Abstract
Background/Objective: The present study focused on the analysis of the Spanish clone belonging to the successful 4,[5],12:i:- monophasic variant of Salmonella enterica serovar Typhimurium. Methods: All isolates of the clone recovered in a Spanish region from human clinical samples between 2008 and 2018 [...] Read more.
Background/Objective: The present study focused on the analysis of the Spanish clone belonging to the successful 4,[5],12:i:- monophasic variant of Salmonella enterica serovar Typhimurium. Methods: All isolates of the clone recovered in a Spanish region from human clinical samples between 2008 and 2018 (N = 14) were investigated using microbiological approaches and genome sequence analysis. In addition, they were compared with isolates from the years 2000 to 2003 (N = 21), which were previously characterized but had not yet been sequenced. Results: Phylogenetic analyses indicate that all isolates are closely related (differing by 1 to 103 SNPs) but belong to two clades termed A and B. With few exceptions, clade A comprised isolates of the first period, also including two “older” control strains, LSP 389/97 and LSP 272/98. Clade B only contained isolates from the second period. Isolates from both periods were resistant to antibiotics and biocides, with almost all resistance genes located on large IncC plasmids, additionally carrying pSLT-derived virulence genes. The number of resistance genes was highly variable, resulting in a total of 22 ABR (antibiotic biocide resistance) profiles. The number of antibiotic resistance genes, but not that of biocide resistance genes, was considerably lower in isolates from the second than from the first period (with averages of 5.5 versus 9.6 genes). Importantly, IS26, which resides in multiple copies within these plasmids, appears to be playing a crucial role in the evolution of resistance, and it was also responsible for the monophasic phenotype, which was associated with four different deletions eliminating the fljAB region. Conclusions: the observed reduction in the number of antibiotic resistance genes could correlate with the loss of adaptive advantage originating from the ban on the use of antibiotics as feed additives implemented in the European Union since 2006, facilitated by the intrinsic instability of the IncC plasmids. Two consecutive IS26 transposition events, which can explain both the clonal relationship of the isolates and their variability, may account for the observed fljAB deletions. Full article
(This article belongs to the Special Issue Genomic Analysis of Antimicrobial Drug-Resistant Bacteria)
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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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21 pages, 3463 KiB  
Article
Hybrid Genome and Clinical Impact of Emerging Extensively Drug-Resistant Priority Bacterial Pathogen Acinetobacter baumannii in Saudi Arabia
by J. Francis Borgio
Life 2025, 15(7), 1094; https://doi.org/10.3390/life15071094 - 12 Jul 2025
Viewed by 383
Abstract
Acinetobacter baumannii is listed by the World Health Organization as an emerging bacterial priority pathogen, the prevalence and multidrug resistance of which have been increasing. This functional genomics study aimed to understand the drug-resistance mechanisms of an extensively drug-resistant (XDR) A. baumannii strain [...] Read more.
Acinetobacter baumannii is listed by the World Health Organization as an emerging bacterial priority pathogen, the prevalence and multidrug resistance of which have been increasing. This functional genomics study aimed to understand the drug-resistance mechanisms of an extensively drug-resistant (XDR) A. baumannii strain (IRMCBCU95U) isolated from a transtracheal aspirate sample from a female patient with end-stage renal disease in Saudi Arabia. The whole genome of IRMCBCU95U (4.3 Mbp) was sequenced using Oxford Nanopore long-read sequencing to identify and compare the antibiotic-resistance profile and genomic features of A. baumannii IRMCBCU95U. The antibiogram of A. baumannii IRMCBCU95U revealed resistance to multiple antibiotics, including cefepime, ceftazidime, ciprofloxacin, imipenem, meropenem and piperacillin/tazobactam. A comparative genomic analysis between IRMCBCU95U and A. baumannii K09-14 and ATCC 19606 identified significant genetic heterogeneity and mosaicism among the strains. This analysis also demonstrated the hybrid nature of the genome of IRMCBCU95U and indicates that horizontal gene transfer may have occurred between these strains. The IRMCBCU95U genome has a diverse range of genes associated with antimicrobial resistance and mobile genetic elements (ISAba1 and IS26) associated with the spread of multidrug resistance. The presence of virulence-associated genes that are linked to iron acquisition, motility and transcriptional regulation confirmed that IRMCBCU95U is a priority human pathogen. The plasmid fragment IncFIB(pNDM-Mar) observed in the strain is homologous to the plasmid in Klebsiella pneumoniae (439 bp; similarity: 99.09%), which supports its antimicrobial resistance. From these observations, it can be concluded that the clinical A. baumannii IRMCBCU95U isolate is an emerging extensively drug-resistant human pathogen with a novel combination of resistance genes and a plasmid fragment. The complex resistome of IRMCBCU95U highlights the urgent need for genomic surveillance in hospital settings in Saudi Arabia to fight against the spread of extensively drug-resistant A. baumannii. Full article
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22 pages, 1347 KiB  
Article
The Microbiological Characteristics and Genomic Surveillance of Carbapenem-Resistant Klebsiella pneumoniae Isolated from Clinical Samples
by Mehwish Rizvi, Noman Khan, Ambreen Fatima, Rabia Bushra, Ale Zehra, Farah Saeed and Khitab Gul
Microorganisms 2025, 13(7), 1577; https://doi.org/10.3390/microorganisms13071577 - 4 Jul 2025
Viewed by 556
Abstract
Klebsiella pneumoniae is a major public health concern due to its role in Gram-negative bacteremia, which leads to high mortality and increased healthcare costs. This study characterizes phenotypic and genomic features of K. pneumoniae isolates from clinical samples in Karachi, Pakistan. Among 507 [...] Read more.
Klebsiella pneumoniae is a major public health concern due to its role in Gram-negative bacteremia, which leads to high mortality and increased healthcare costs. This study characterizes phenotypic and genomic features of K. pneumoniae isolates from clinical samples in Karachi, Pakistan. Among 507 isolates, 213 (42%) were carbapenem-resistant based on disk diffusion and MIC testing. Urine (29.7%) and blood (28.3%) were the most common sources, with infections predominantly affecting males (64.7%) and individuals aged 50–70 years. Colistin was the only antibiotic showing consistent activity against these isolates. The whole-genome sequencing of 24 carbapenem-resistant K. pneumoniae (CR-KP) isolates revealed blaNDM-5 (45.8%) as the dominant carbapenemase gene, followed by blaNDM-1 (12.5%) and blaOXA-232 (54.2%). Other detected blaOXA variants included blaOXA-1, blaOXA-4, blaOXA-10, and blaOXA-18. The predominant beta-lactamase gene was blaCTX-M-15 (91.6%), followed by blaCTX-M-163, blaCTX-M-186, and blaCTX-M-194. Sequence types ST147, ST231, ST29, and ST11 were associated with resistance. Plasmid profiling revealed IncR (61.5%), IncL (15.4%), and IncC (7.7%) as common plasmid types. Importantly, resistance was driven not only by acquired genes but also by chromosomal mutations. Porin mutations in OmpK36 and OmpK37 (e.g., P170M, I128M, N230G, A217S) reduced drug influx, while acrR and ramR mutations (e.g., P161R, G164A, P157*) led to efflux pump overexpression, enhancing resistance to fluoroquinolones and tigecycline. These findings highlight a complex resistance landscape driven by diverse carbapenemases and ESBLs, underlining the urgent need for robust antimicrobial stewardship and surveillance strategies. Full article
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16 pages, 1933 KiB  
Article
Mapping Integron-Associated AMR Genes in Whole Genome Sequences of Salmonella Typhimurium from Dairy Cattle
by Sami Ullah Khan Bahadur, Nora Jean Nealon, Joshua B. Daniels, Muhammad Usman Zaheer, Mo Salman and Sangeeta Rao
Antibiotics 2025, 14(7), 633; https://doi.org/10.3390/antibiotics14070633 - 21 Jun 2025
Viewed by 593
Abstract
Background: Antimicrobial resistance (AMR) is a critical global health threat, with AMR Salmonella enterica serovar Typhimurium strains being a major foodborne pathogen. Integrons, a type of mobile genetic element, capture and transfer resistance genes, thereby playing a role in the spread of AMR. Objectives: [...] Read more.
Background: Antimicrobial resistance (AMR) is a critical global health threat, with AMR Salmonella enterica serovar Typhimurium strains being a major foodborne pathogen. Integrons, a type of mobile genetic element, capture and transfer resistance genes, thereby playing a role in the spread of AMR. Objectives: This study aimed to characterize the locations of integrons carrying AMR genes within the whole genomes of 32 Salmonella Typhimurium isolates collected from dairy cattle by two U.S. Veterinary Diagnostic Laboratories between 2009 and 2012. Methods: Class I integrons were sequenced from PCR-amplified products. DNA was extracted, quantified, barcoded, and sequenced on the Illumina MiSeq platform. Whole genome sequences were trimmed and assembled using the SPAdes assembler in Geneious Prime®, and plasmids were identified with the PlasmidFinder pipeline in Linux. Integron locations were determined by aligning their sequences with whole genome contigs and plasmids, while AMR genes were identified through BLAST with the MEGARes 3.0 database and confirmed by alignment with isolate, plasmid, and integron sequences. Statistical analysis was applied to compare the proportions of isolates harboring integrons on their chromosome versus plasmids and also to examine the associations between integron presence and AMR gene presence. Results: Seven plasmid types were identified from all isolates: IncFII(S) (n = 14), IncFIB(S) (n = 13), IncC (n = 7), Inc1-I(Alpha) (n = 3), and ColpVC, Col(pAHAD28), and Col8282 (1 isolate each). Of the 32 isolates, 16 (50%) carried at least one size of integron. Twelve of them carried both 1000 and 1200 bp; 3 carried only 1000 bp and 1 carried 1800 bp integrons. Of the 15 isolates that carried 1000 bp integron, 12 harbored it on IncFIB(S) plasmids, 2 on IncC plasmids, and 1 on the chromosome. The 1200 bp integrons from all 12 isolates were located on chromosomes. There were significant positive associations between the presence of integrons and the presence of several AMR genes including sul1, aadA2, blaCARB-2, qacEdelta1, tet(G), and floR (p < 0.05). AMR genes were located as follows: aadA2 on IncFIB(S) and IncC plasmids; blaCMY-2 on IncC plasmid; qacEdelta1 on IncFIB(S), IncC, and chromosome; blaCARB-2, floR, tet(A) and tet(G) on the chromosome. Conclusions: The findings highlight the genomic and plasmid complexity of Salmonella Typhimurium which is impacted by the presence and location of integrons, and this study provides genomic insights that can inform efforts to enhance food safety and protect both animal and public health. Full article
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14 pages, 1541 KiB  
Article
First Report in the Americas of S. enterica Var. Enteritidis Carrying blaNDM-1 in a Putatively New Sub-Lineage of IncC2 Plasmids
by Nicolás F. Cordeiro, Romina Papa-Ezdra, Germán Traglia, Inés Bado, Virginia García-Fulgueiras, María N. Cortinas, Leticia Caiata, Mariana López-Vega, Ana Otero, Martín López, Patricia Hitateguy, Cristina Mogdasy and Rafael Vignoli
Antibiotics 2025, 14(6), 620; https://doi.org/10.3390/antibiotics14060620 - 18 Jun 2025
Viewed by 550
Abstract
Background: Infections caused by carbapenem-resistant Enterobacterales have steadily multiplied over time, becoming a major threat to healthcare systems due to limited therapeutic options and high case-fatality rates. Case report: We studied a patient who, after being discharged from an ICU, developed salmonellosis caused [...] Read more.
Background: Infections caused by carbapenem-resistant Enterobacterales have steadily multiplied over time, becoming a major threat to healthcare systems due to limited therapeutic options and high case-fatality rates. Case report: We studied a patient who, after being discharged from an ICU, developed salmonellosis caused by an antibiotic-susceptible S. enteritidis. After undergoing treatment with ciprofloxacin, the patient presented an episode of asymptomatic bacteriuria originated by a carbapenem and ciprofloxacin-resistant S. enteritidis. Results: Whole genome sequencing analysis revealed that both Salmonella isolates belonged to the same strain, and that isolate SEn_T2 acquired a plasmid carrying both blaNDM-1 and qnrA1 genes (pIncCSEn) which was previously present in the patient’s gut in at least one Enterobacter cloacae isolate. Additionally, pIncCSEN was identified as a putatively new sub-lineage of IncC2 plasmids which lacked the first copy of the methyltransferase gene dcm and the rhs gene. The resistance genes blaNDM-1 and qnrA1 were incorporated into a Tn21-derived transposon that included a complex class 1 integron whose genetic arrangement was: intI1- dfrA12- orfF- aadA2- qacEΔ1-sul1-ISCR1- trpF- ble- blaNDM-1 (in reverse direction)- ISAba125-ISCR1- qnrA- cmlA1- qacEΔ1-sul1. Conclusions: Antimicrobial persistence and co-selection of antibiotic resistance play an important role in the dissemination of antimicrobial resistance genes; in this regard, a joint effort involving the infection control team, effective antibiotic stewardship, and genomic surveillance could help mitigate the spread of these multidrug resistant microorganisms. Full article
(This article belongs to the Special Issue Multidrug-Resistance Patterns in Infectious Pathogens)
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11 pages, 1844 KiB  
Brief Report
The Co-Existence of mcr-1.1 and mcr-3.5 in Escherichia coli Isolated from Clinical Samples in Thailand
by Panida Nobthai, Sirigade Ruekit, Dutsadee Peerapongpaisarn, Prawet Sukhchat, Brett E. Swierczewski, Nattaya Ruamsap and Paphavee Lertsethtakarn
Antibiotics 2025, 14(6), 596; https://doi.org/10.3390/antibiotics14060596 - 10 Jun 2025
Viewed by 643
Abstract
The emergence of colistin resistance poses a significant threat to its efficacy as a last-line treatment against multidrug-resistant Gram-negative bacterial infections. In this study, 178 multi-drug resistant (MDR) Escherichia coli isolates collected from clinical samples at Queen Sirikit Naval Hospital, Chonburi, Thailand, were [...] Read more.
The emergence of colistin resistance poses a significant threat to its efficacy as a last-line treatment against multidrug-resistant Gram-negative bacterial infections. In this study, 178 multi-drug resistant (MDR) Escherichia coli isolates collected from clinical samples at Queen Sirikit Naval Hospital, Chonburi, Thailand, were evaluated for colistin resistance. Of these, six were identified as mcr gene carriers, mediating colistin resistance. Specifically, mcr-1 was detected in three E. coli isolates, mcr-3 was detected in one E. coli isolate, and mcr-1 and mcr-3 were detected in two E. coli isolates, designated AMR-0220 and AMR-0361. Whole-genome sequencing and bioinformatics analysis revealed that AMR-0220 and AMR-0361 belonged to ST410 and ST617 lineages, respectively. Both isolates carried multiple plasmids, with mcr-1.1 located on an IncX4-type plasmid that is closely related to previously reported mcr-1.1-carrying IncX4 plasmids. In contrast, mcr-3.5 was identified on distinct plasmid backbones: an IncFIB-type plasmid in AMR-0220 and an IncFII-type plasmid in AMR-0361. Overall, our findings demonstrate that the mcr genes found in E. coli isolates in this region are located on different mobile genetic elements, indicating the potential for a widespread dissemination of colistin resistance among Gram-negative bacteria throughout Thailand’s healthcare system. Full article
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18 pages, 546 KiB  
Article
Outbreak of NDM-5-Producing Proteus mirabilis During the COVID-19 Pandemic in an Argentine Hospital
by Barbara Ghiglione, Ana Paula Rodriguez, María Sol Haim, Laura Esther Friedman, Nilton Lincopan, María Eugenia Ochiuzzi and José Alejandro Di Conza
Antibiotics 2025, 14(6), 557; https://doi.org/10.3390/antibiotics14060557 - 29 May 2025
Viewed by 631
Abstract
Background: During the COVID-19 pandemic, the emergence of multidrug-resistant (MDR) pathogens, driven by heightened antibiotic usage and device-associated infections, has posed significant challenges to healthcare. This study reports an outbreak of Proteus mirabilis producing NDM-5 and CTX-M-15 β-lactamases in a hospital in Buenos [...] Read more.
Background: During the COVID-19 pandemic, the emergence of multidrug-resistant (MDR) pathogens, driven by heightened antibiotic usage and device-associated infections, has posed significant challenges to healthcare. This study reports an outbreak of Proteus mirabilis producing NDM-5 and CTX-M-15 β-lactamases in a hospital in Buenos Aires, Argentina, from October 2020 to April 2021. To our knowledge, this represents the first documented outbreak of NDM-5-producing P. mirabilis in the country. Methods: A total of 82 isolates were recovered from 40 patients, with 41.5% from blood cultures and 18.3% from respiratory and urinary samples, among others. Antimicrobial susceptibility testing, PCR-based methods, and MALDI-TOF MS cluster analysis were conducted. Whole genome sequencing (WGS) was performed to characterize the MLST, resistome and plasmid content. Biofilm formation assays and in vitro rifampicin susceptibility tests were also conducted. Result: Most isolates exhibited resistance to carbapenems, cephalosporins, aminoglycosides, and fluoroquinolones, while retaining susceptibility to aztreonam. Genetic analysis confirmed the co-presence of the blaNDM-5 and blaCTX-M-15 genes. Clonal relationships was supported by PCR-based typing and MALDI-TOF MS cluster analysis. WGS revealed a resistome comprising 25 resistance genes, including rmtB and both β-lactamases, as well as the presence of an incomplete IncQ1 replicon associated with multiple resistance determinants. MLST classified this clone as belonging to ST135. Despite the biofilm-forming capacity observed across strains, rifampicin demonstrated potential for disrupting established biofilms at concentrations ≥32 µg/mL in vitro. The MDR profile of the outbreak strain significantly limited therapeutic options. Conclusions: This study highlights the growing threat of NDM-producing P. mirabilis in Argentina. The absence of surveillance cultures from the index case limits insights into the outbreak’s origin. These findings underscore the importance of integrating genomic surveillance into infection control protocols to mitigate the spread of MDR pathogens. Full article
(This article belongs to the Special Issue Multidrug-Resistance Patterns in Infectious Pathogens)
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25 pages, 3662 KiB  
Article
Deciphering the Causes of IbfA-Mediated Abortive Infection in the P22-like Phage UAB_Phi20
by Júlia López-Pérez, Pilar Cortés, Susana Campoy, Ivan Erill and Montserrat Llagostera
Int. J. Mol. Sci. 2025, 26(10), 4918; https://doi.org/10.3390/ijms26104918 - 20 May 2025
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Abstract
The study of bacterial defense mechanisms against phages is becoming increasingly relevant due to their impact on the effectiveness of phage therapy. Employing a multifaceted approach that combines bioinformatics, molecular microbiology, TEM microscopy, and conventional microbiology techniques, here, we identify the ibfA gene [...] Read more.
The study of bacterial defense mechanisms against phages is becoming increasingly relevant due to their impact on the effectiveness of phage therapy. Employing a multifaceted approach that combines bioinformatics, molecular microbiology, TEM microscopy, and conventional microbiology techniques, here, we identify the ibfA gene as a novel defense factor targeting the virulent phage UAB_Phi20, acquired by Salmonella Typhimurium through lateral transfer on the IncI1α conjugative plasmid pUA1135 after oral phage therapy in broilers. IbfA, a two-domain protein containing ATPase and TOPRIM domains, significantly reduces UAB_Phi20 productivity, as indicated by decreased EOP, ECOI, and a diminished burst size, potentially reducing cellular viability without causing observable lysis. Our results indicate that IbfA enhances the transcription of early genes, including the antirepressor ant, which inhibits the C2 repressor of the lytic cycle. This may cause an imbalance in Cro/C2 concentration, leading to the observed reduction in the transcription of late genes encoding structural and cellular lysis proteins, and resulting in the abortion of UAB_Phi20 infection. Full article
(This article belongs to the Special Issue Exploring Phage–Host Interactions: Novel Findings and Perspectives)
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23 pages, 432 KiB  
Review
One Health at Risk: Plasmid-Mediated Spread of mcr-1 Across Clinical, Agricultural, and Environmental Ecosystems
by Abdelaziz Touati, Nasir Adam Ibrahim, Assia Mairi, Hassina Kirat, Nosiba S. Basher and Takfarinas Idres
Antibiotics 2025, 14(5), 506; https://doi.org/10.3390/antibiotics14050506 - 15 May 2025
Viewed by 963
Abstract
The global dissemination of plasmid-mediated mcr genes, which confer resistance to the last-resort antibiotic colistin, represents a critical public health challenge driven by the interplay of clinical, agricultural, and environmental factors. This review examines the genetic and ecological dynamics of mcr-bearing plasmids, [...] Read more.
The global dissemination of plasmid-mediated mcr genes, which confer resistance to the last-resort antibiotic colistin, represents a critical public health challenge driven by the interplay of clinical, agricultural, and environmental factors. This review examines the genetic and ecological dynamics of mcr-bearing plasmids, focusing on their role in disseminating colistin resistance across diverse bacterial hosts and ecosystems. Key plasmid families demonstrate distinct evolutionary strategies, including IncI2, IncHI2, and IncX4. IncI2 plasmids favor stability in livestock and clinical settings. IncHI2 plasmids, on the other hand, leverage transposons to co-select for multidrug resistance, while IncX4 plasmids achieve global dissemination through streamlined, conjugation-efficient architectures. The pervasive spread of mcr genes is exacerbated by their integration into chromosomes via mobile genetic elements and co-selection with resistance to other antibiotic classes, amplifying multidrug-resistant phenotypes. Environmental reservoirs, food chains, and anthropogenic practices further facilitate cross-niche transmission, underscoring the interconnectedness of resistance under the One Health framework. Addressing this crisis requires coordinated strategies, including reducing colistin misuse in agriculture, enhancing surveillance of high-risk plasmid types, and fostering international collaboration to preserve antimicrobial efficacy and mitigate the threat of untreatable infections. Full article
(This article belongs to the Special Issue A One Health Approach to Antimicrobial Resistance, 2nd Edition)
25 pages, 1360 KiB  
Article
Phenotypic and Genotypic Characterization of ESBL-, AmpC-, and Carbapenemase-Producing Klebsiella pneumoniae and High-Risk Escherichia coli CC131, with the First Report of ST1193 as a Causative Agent of Urinary Tract Infections in Human Patients in Algeria
by Hajer Ziadi, Fadela Chougrani, Abderrahim Cheriguene, Leticia Carballeira, Vanesa García and Azucena Mora
Antibiotics 2025, 14(5), 485; https://doi.org/10.3390/antibiotics14050485 - 9 May 2025
Viewed by 1243
Abstract
Background: High-risk Escherichia coli clones, such as sequence type (ST)131 and ST1193, along with multidrug-resistant (MDR) Klebsiella pneumoniae, are globally recognized for their significant role in urinary tract infections (UTIs). This study aimed to provide an overview of the virulence factors, clonal [...] Read more.
Background: High-risk Escherichia coli clones, such as sequence type (ST)131 and ST1193, along with multidrug-resistant (MDR) Klebsiella pneumoniae, are globally recognized for their significant role in urinary tract infections (UTIs). This study aimed to provide an overview of the virulence factors, clonal diversity, and antibiotic resistance profiles of extended-spectrum cephalosporin (ESC)-E. coli and K. pneumoniae causing UTIs in humans in the Tebessa region of Algeria. Methods: Forty E. coli and 17 K. pneumoniae isolates exhibiting ESC-resistance were recovered (July 2022–January 2024) from urine samples of patients at three healthcare facilities to be phenotypically and genotypically characterized. Whole genome sequencing (WGS) was performed on the ST1193 clone. Results: Among K. pneumoniae isolates, all except one harbored CTX-M-15, with a single isolate carrying blaCTX-M-194. Additionally, two K. pneumoniae isolates co-harboring blaCTX-M-15 and blaNDM exhibited phenotypic and genotypic hypervirulence traits. Fluoroquinolone resistance (FQR) was detected in 94.1% of K. pneumoniae isolates. The E. coli isolates carried diverse ESC-resistance genes, including CTX-M-15 (87.5%), CTX-M-27 (5%), CTX-M-1, CMY-59, and CMY-166 (2.5% each). Co-carriage of blaESC and blaOXA-48 was identified in three E. coli isolates, while 62.5% exhibited FQR. Phylogenetic analysis revealed that 52.5% of E. coli belonged to phylogroup B2, including the high-risk clonal complex (CC)131 CH40-30 (17 isolates) and ST1193 (one isolate). In silico analysis of the ST1193 genome determined O75:H5-B2 (CH14-64), and the carriage of IncI1-I(Alpha) and IncF [F-:A1:B10] plasmids. Notably, core genome single-nucleotide polymorphism (SNP) analysis demonstrated high similarity between the Algerian ST1193 isolate and a previously annotated genome from a hospital in Northwest Spain. Conclusions: This study highlights the spread and genetic diversity of E. coli CC131 CH40-30 and hypervirulent K. pneumoniae clones in Algeria. It represents the first report of a CTX-M-15-carrying E. coli ST1193 in the region. The findings emphasize the urgent need for antibiotic optimization programs and enhanced surveillance to curb the dissemination of high-risk clones that pose an increasing public health threat in Algeria. A simplified method based on virulence traits for E. coli and K. pneumoniae is proposed here for antimicrobial resistance (AMR) monitoring. Full article
(This article belongs to the Special Issue Genomic Analysis of Antimicrobial Drug-Resistant Bacteria)
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