Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts

Objective: This study aimed to investigate the identification of blaCARBA-positive multidrug-resistant Mixta calida isolates from human hosts and to elucidate their genomic determinants in a species-wide context. Methods: Two carbapenemase-producing M. calida isolates were received by the Galway Ref...

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Main Authors: Francesca McDonagh, Kate Ryan, Aneta Kovářová, Anna Tumeo, Christina Clarke, Martin Cormican, Georgios Miliotis
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:International Journal of Medical Microbiology
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Online Access:http://www.sciencedirect.com/science/article/pii/S1438422125000256
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author Francesca McDonagh
Kate Ryan
Aneta Kovářová
Anna Tumeo
Christina Clarke
Martin Cormican
Georgios Miliotis
author_facet Francesca McDonagh
Kate Ryan
Aneta Kovářová
Anna Tumeo
Christina Clarke
Martin Cormican
Georgios Miliotis
author_sort Francesca McDonagh
collection DOAJ
description Objective: This study aimed to investigate the identification of blaCARBA-positive multidrug-resistant Mixta calida isolates from human hosts and to elucidate their genomic determinants in a species-wide context. Methods: Two carbapenemase-producing M. calida isolates were received by the Galway Reference Laboratory Service in Ireland between June and July 2024. One isolate originated from a sputum sample, while the other was recovered from a routine screening rectal swab. Initial identification was performed using MALDI-ToF mass spectrometry, with genomic confirmation via 16S rRNA sequencing, digital DNA-DNA hybridization, and Average Nucleotide Identity analysis. Antimicrobial susceptibility testing was conducted using a MicroScan panel, following EUCAST and CLSI guidelines. Whole-genome sequencing, plasmid replicon typing, and antibiotic-resistance-gene and virulence-factor profiling were employed. Comparative analysis included all additional canonical M. calida genomes from NCBI database. Results: Both Irish isolates were taxonomically placed as M. calida and exhibited multidrug resistance against penicillins, cephalosporins, monobactams and ertapenem. The acquired genes blaKPC-3, blaOXA-9, and blaTEM-122 were detected on plasmid-borne contigs, indicating horizontal acquisition. Seven plasmid replicon types were shared between the two isolates. Both plasmid replicons and acquired antimicrobial-resistance-genes (ARGs) were seldomly identified across the species. Phylogenetic inference based on core genome analysis identified a monophyletic cluster, suggesting a single introductory event. Conclusion: This study documents a dual occurrence of blaCARBA-positive M. calida in human colonisation and infection. The findings highlight the potential for horizontal-gene-transfer to drive the emergence of multidrug-resistant profiles in the species, underscoring the need for enhanced surveillance, diagnostic precision, and targeted infection control strategies to mitigate public health risks. Impact statement: This study reports blaESBL and blaCARBA-positive multi-drug resistant Mixta calida isolates from distinct human hosts. Genomic analysis revealed the co-occurrence of plasmid-borne resistance genes blaKPC-3, blaOXA-9, and blaTEM-122. Species-wide phylogenetic analysis grouped the two isolates into a monophyletic cluster, suggesting a single introductory event.
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spelling doaj-art-1a53ef277be74c95907eaf29f41f2ed02025-08-20T03:41:43ZengElsevierInternational Journal of Medical Microbiology1438-42212025-09-0132015166910.1016/j.ijmm.2025.151669Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human HostsFrancesca McDonagh0Kate Ryan1Aneta Kovářová2Anna Tumeo3Christina Clarke4Martin Cormican5Georgios Miliotis6Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, IrelandAntimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, IrelandAntimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, IrelandAntimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, IrelandDepartment of Medical Microbiology, Health Services Executive, Galway University Hospital, Galway, IrelandDepartment of Medical Microbiology, Health Services Executive, Galway University Hospital, Galway, IrelandAntimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland; Centre for One Health, Ryan Institute, University of Galway, Galway, Ireland; Corresponding author at: Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland.Objective: This study aimed to investigate the identification of blaCARBA-positive multidrug-resistant Mixta calida isolates from human hosts and to elucidate their genomic determinants in a species-wide context. Methods: Two carbapenemase-producing M. calida isolates were received by the Galway Reference Laboratory Service in Ireland between June and July 2024. One isolate originated from a sputum sample, while the other was recovered from a routine screening rectal swab. Initial identification was performed using MALDI-ToF mass spectrometry, with genomic confirmation via 16S rRNA sequencing, digital DNA-DNA hybridization, and Average Nucleotide Identity analysis. Antimicrobial susceptibility testing was conducted using a MicroScan panel, following EUCAST and CLSI guidelines. Whole-genome sequencing, plasmid replicon typing, and antibiotic-resistance-gene and virulence-factor profiling were employed. Comparative analysis included all additional canonical M. calida genomes from NCBI database. Results: Both Irish isolates were taxonomically placed as M. calida and exhibited multidrug resistance against penicillins, cephalosporins, monobactams and ertapenem. The acquired genes blaKPC-3, blaOXA-9, and blaTEM-122 were detected on plasmid-borne contigs, indicating horizontal acquisition. Seven plasmid replicon types were shared between the two isolates. Both plasmid replicons and acquired antimicrobial-resistance-genes (ARGs) were seldomly identified across the species. Phylogenetic inference based on core genome analysis identified a monophyletic cluster, suggesting a single introductory event. Conclusion: This study documents a dual occurrence of blaCARBA-positive M. calida in human colonisation and infection. The findings highlight the potential for horizontal-gene-transfer to drive the emergence of multidrug-resistant profiles in the species, underscoring the need for enhanced surveillance, diagnostic precision, and targeted infection control strategies to mitigate public health risks. Impact statement: This study reports blaESBL and blaCARBA-positive multi-drug resistant Mixta calida isolates from distinct human hosts. Genomic analysis revealed the co-occurrence of plasmid-borne resistance genes blaKPC-3, blaOXA-9, and blaTEM-122. Species-wide phylogenetic analysis grouped the two isolates into a monophyletic cluster, suggesting a single introductory event.http://www.sciencedirect.com/science/article/pii/S1438422125000256Mixta calidablaKPC-3blaOXA-9blaTEM-122
spellingShingle Francesca McDonagh
Kate Ryan
Aneta Kovářová
Anna Tumeo
Christina Clarke
Martin Cormican
Georgios Miliotis
Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
International Journal of Medical Microbiology
Mixta calida
blaKPC-3
blaOXA-9
blaTEM-122
title Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
title_full Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
title_fullStr Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
title_full_unstemmed Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
title_short Identification of blaESBL- and blaCARBA- Positive Multi-Drug Resistant Mixta calida Isolates from Distinct Human Hosts
title_sort identification of blaesbl and blacarba positive multi drug resistant mixta calida isolates from distinct human hosts
topic Mixta calida
blaKPC-3
blaOXA-9
blaTEM-122
url http://www.sciencedirect.com/science/article/pii/S1438422125000256
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