Infection caused by Cupriavidus gilardii in a convalescent COVID-19 patient

Genomic insights and phenotypic characterization of three multidrug resistant Cupriavidus strains from the cystic fibrosis lung

AIMS

We aimed to investigate phenotypic and genomic traits of three Cupriavidus spp. isolates recovered from people with cystic fibrosis (PWCF). These bacteria are recognized as emerging pathogens in PWCF.

METHODS AND RESULTS

Using short and long sequencing reads, we assembled three hybrid complete genomes for the genus Cupriavidus, adding to the 45 published currently, describing multipartite genomes and plasmids. The isolates likely represent three different species, and they carry a cumulative total of 30 antibiotic resistance genes with high homology to well-characterized resistance determinants from other bacteria. Multidrug resistance to antibiotics used in CF management was observed in all three isolates. However, two treatments were active across all isolates: cefotaxime and piperacillin/tazobactam. Biofilm formation was only seen at physiological temperatures (37°C) and lost at 20°C and all isolates had low lethality in Galleria mellonella larvae. Isolates demonstrated variable motility, with one non-motile isolate carrying a disrupted flhD transcriptional regulator, abolishing flagella expression.

CONCLUSIONS

Our Cupriavidus spp. isolates showed considerable genomic and phenotypic variability that may impact their virulence and treatment in PWCF, where multidrug resistance will negate treatments and biofilm formation and motility play key roles in infection establishment, as seen in CF pathogens like Pseudomonas aeruginosa. More detailed investigation of clinical Cupriavidus isolates is needed for full understanding of the risk they pose to PWCF.

Structural diversity and clustering of bacterial flagellar outer domains

Supercoiled flagellar filaments function as mechanical propellers within the bacterial flagellum complex, playing a crucial role in motility. Flagellin, the building block of the filament, features a conserved inner D0/D1 core domain across different bacterial species. In contrast, approximately half of the flagellins possess additional, highly divergent outer domain(s), suggesting varied functional potential. In this study, we report atomic structures of flagellar filaments from three distinct bacterial species: Cupriavidus gilardii, Stenotrophomonas maltophilia, and Geovibrio thiophilus. Our findings reveal that the flagella from the facultative anaerobic G. thiophilus possesses a significantly more negatively charged surface, potentially enabling adhesion to positively charged minerals. Furthermore, we analyze all AlphaFold predicted structures for annotated bacterial flagellins, categorizing the flagellin outer domains into 682 structural clusters. This classification provides insights into the prevalence and experimental verification of these outer domains. Remarkably, two of the flagellar structures reported herein belong to a distinct cluster, indicating additional opportunities on the study of the functional diversity of flagellar outer domains. Our findings underscore the complexity of bacterial flagellins and open up possibilities for future studies into their varied roles beyond motility.

Resistance to carbapenems in the urban soil isolate Cupriavidus taiwanensis S2-1-W is associated with OXA-1206, a newly discovered carbapenemase

AIMS

Cupriavidus isolates are found in environmental and clinical samples and are often resistant to carbapenems, which are last-resort antibiotics. However, their carbapenem-resistance molecular mechanisms remain unknown. This study aimed to (i) characterize and sequence the carbapenem-resistant soil isolate Cupriavidus taiwanensis S2-1-W to uncover its antibiotic resistance determinants; and (ii) clone and characterize a putative novel carbapenemase gene identified in this isolate.

METHODS AND RESULTS

Antibiotic susceptibility testing of C. taiwanensis S2-1-W revealed that it was resistant to most carbapenems, other β-lactams, and aminoglycosides tested. Genome sequencing of this isolate revealed a complex chromosomal resistome that included multidrug efflux pump genes, one aminoglycoside transferase gene, and three β-lactamase genes. Among them, we identified a novel putative class D β-lactamase gene (blaOXA-1206) that is highly conserved among other sequenced C. taiwanensis isolates. Cloning and characterization of blaOXA-1206 confirmed that it encodes for a newly discovered carbapenemase (OXA-1206) that confers resistance to carbapenems and other β-lactams.

CONCLUSION

Carbapenem-resistance in C. taiwanensis S2-1-W is associated with a newly discovered carbapenemase, OXA-1206.

Genomic Sequencing of Clinical Cupriavidus gilardii Isolates Revealed Their Diverse Antimicrobial Resistance Mechanisms

Purpose

Cupriavidus gilardii is an emerging multidrug-resistant pathogen found in many environments and few clinical samples. The clinical infectiousness, pathogenicity, and resistance mechanisms of C. gilardii are still unclear due to the lack of clinical and sequencing data. We need to obtain insight into the clinical characteristics, virulence, and resistance mechanisms of C. gilardii.

Patients and Methods

We isolated five C. gilardii isolates from hospitalized patients and carried out assay, culture and genome sequencing. We analyzed the genomic features of clinical C. gilardii isolates and took insight into their clinical characteristics, virulence, and resistance mechanisms.

Results

These isolates were resistant to meropenem, gentamicin, and other antimicrobials due to intrinsic resistance genes. Furthermore, the sequencing results revealed the widespread presence of the MCR-5.1 gene in C. gilardii. The virulence magnitude of C. gilardii is closely correlated with the number of virulence factors they carry. Some C. gilardii strains can acquire resistance to levofloxacin through gyrA gene mutation during treatment. The diverse antimicrobial resistance mechanisms challenge the treatment of C. gilardii infections.

Conclusion

We present the genomic characteristics of clinically isolated C. gilardii to improve (i) our understanding of this pathogen and (ii) treatment options.