Epidemic Clostridioides difficile Ribotype 027 Lineages: Comparisons of Texas Versus Worldwide Strains.

Area of Science:

• Microbiology
• Genomics
• Epidemiology

Background:

• The epidemic Clostridioides difficile (C. diff) ribotype 027 strain arose from two fluoroquinolone-resistant lineages (FQR1, FQR2).
• While originating in North America, large-scale genomic investigations of C. diff ribotype 027 epidemiology in the U.S. were lacking.

Purpose of the Study:

• To investigate the epidemiology and evolution of Clostridioides difficile ribotype 027 in the United States using whole genome sequencing.
• To compare U.S. strains with global isolates to understand macro- and microevolutionary patterns.

Main Methods:

• Whole genome sequencing and SNP analysis of 76 Texas C. diff ribotype 027 isolates and 32 global strains.
• Phylogenetic tree construction using maximum-likelihood and Bayesian analyses incorporating temporal and geographic data.

Main Results:

• Identified 2841 SNPs, distinguishing FQR1 and FQR2 lineages with 28 SNPs.
• Discovered five pre-epidemic strains.
• Texas strains showed unique clustering and resistance genes, indicating spatiotemporal influence on ribotype 027 genetics.

Conclusions:

• Clostridioides difficile ribotype 027 lineages emerged earlier, correlating with fluoroquinolone use.
• Both FQR1 and FQR2 lineages are present in Texas.
• Geographic evolution has created region-specific public health threats from these C. diff strains.