Integrated Whole-Genome Sequencing and In Silico Characterization of Cerro and Schwarzengrund from Brazil.

BACKGROUND

is a bacterium that causes foodborne infections. This study characterized two strains isolated from cheese and beef in Brazil using whole-genome sequencing (WGS).

OBJECTIVES

We evaluated their antimicrobial resistance profiles, virulence factors, plasmid content, serotypes and phylogenetic relationships.

METHODS

DNA was extracted and sequenced on the NovaSeq 6000 platform; the pangenome was assembled using the Roary tool; and the phylogenetic tree was constructed via IQ-TREE.

RESULTS AND DISCUSSION

For contextualization and comparison, 3493 genomes of Brazilian origin from NCBI were analyzed. In our isolates, both strains carried the gene, while only Schwarzengrund harbored the gene and the plasmid. Cerro presented the islands SPI-1, SPI-2, SPI-3, SPI-4, SPI-5 and SPI-9, while Schwarzengrund also possessed SPI-13 and SPI-14. Upon comparison with other Brazilian genomes, we observed that Cerro and Schwarzengrund represented only 0.40% and 2.03% of the national database, respectively. Furthermore, they revealed that Schwarzengrund presented higher levels of antimicrobial resistance, a finding supported by the higher frequency of plasmids in this serovar. Furthermore, national data corroborated our findings that SPI-13 and SPI-14 were absent in Cerro. A virulence analysis revealed distinct profiles: the and genes were present in the Schwarzengrund isolates, while the and 1 family genes were exclusive to Cerro. The results indicated that the sequenced strains have pathogenic potential but exhibit low levels of antimicrobial resistance compared to national data. The greater diversity of SPIs in Schwarzengrund explains their prevalence and higher virulence potential.

CONCLUSIONS

Finally, the serovars exhibit distinct virulence profiles, which results in different clinical outcomes.