Clonal clusters of multidrug-resistant Brazilian Corynebacterium striatum strains reveal putative virulence traits.

OBJECTIVES

This study presents the comparative analysis of 26 multidrug-resistant (MDR) C. striatum strains isolated in Brazil.

METHODS

Additional genomes from international sources were incorporated. The analyses encompassed in vitro antimicrobial susceptibility testing and an in silico workflow for genomic similarity comparison, phylogenetic reconstruction, genomic clustering, pangenome analysis, mobilome content, virulence prediction, and functional annotation of unique proteins and putative virulence clusters.

RESULTS

Strong in silico evidence of clonality among several Brazilian isolates was obtained at the same time that some strains consistently indicated a divergent genomic profile. There are 196 unique coding sequences (CDSs) across the Brazilian IHPs. Of particular interest, strain IHP2030 carried an exclusive fimbria, sharing less than 50% similarity with other fimbriae in the dataset. Yet, structural predictions suggested conservation of key structural domains typically associated with fimbrial proteins. Mobilome content analysis revealed that IHPs strains were overall similar, differing primarily in the number of insertion sequences and in the presence or absence of CRISPR-Cas defense systems. Regarding virulence, an exclusive cluster in IHP2050 and IHP2060 suggests adaptive advantages associated with their respective environments of isolation.

CONCLUSION

This study reveals a complex genomic landscape among Brazilian MDR C. striatum strains, marked by clonal dissemination alongside strain-level genetic variation in accessory genomes, mobilome composition, and virulence-associated gene repertoires, providing genomic evidence of diversification within hospital-associated lineages.