Question

The CDC has determined that the E. coli O157:H7 strain that caused the multistate outbreak associated with redleaf and greenleaf lettuce was the same strain that caused an outbreak in 2017, which was linked to leafy greens in the US and romain lettuce in Canada; but it was not the same strain that caused the outbreak in 2018 that was linked to romaine lettuce grown in Yuma, AZ. What method do epidemiologists at the CDC and local public health laboratories use to determine whether the same strain is causing an outbreak and ultimately link it to a source?

	a) Gram staining and light microscopy to distinguish EHEC strains
	b) Biochemical assays to distinguish EHEC strains
	c) Fluorescence microscopy to distinguish EHEC strains
	d) Whole genome sequencing to distinguish EHEC strains
	e) Metagenome sequencing to distinguish EHEC strains

Answer 1

Whole-genome sequencing (WGS) is a genotyping tool. It enables mapping of entire DNA. Genome is unique blueprint of organism and gives unique identity of the organism. WGS allows analysis of entire genome of pathogen allowing highly efficient discrimination between even highly related lineages of bacteria. This method has revolutionized the outbreak analysis in hospitals making it affordable and precise.
Thus, best answer is D, While Genome Sequencing.