Abstract
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Researchers at the Milner Center for Evolution at the University of Bath in the U.K. have demonstrated that sequencing the DNA of Methicillin-resistant Staphylococcus aureus (MRSA) can help identify patients most at risk of death from MRSA, and could provide the basis for the development of new therapies to combat these sometimes-deadly infections. Methicillin-resistant S. aureus (MRSA) has become resistant to most antibiotics, and up to 20% of patients with severe infections die.
“We phenotyped a collection of sequenced clinical S. aureus isolates from [about 300] patients with bloodstream infections, representing two globally important clonal types, CC22 and CC30,” wrote the investigators. “By adopting a genome-wide association study approach, we identified and functionally verified several genetic loci that affect the expression of cytolytic toxicity and biofilm formation. By analyzing the pooled data comprising bacterial genotype and phenotype together with clinical metadata within a machine-learning framework, we found significant clonal differences in the determinants most predictive of poor infection outcome.”
The researchers found that for CC22 strains, both their toxicity and biofilm-forming abilities played a significant role in whether the patient survived infection. However, these factors did not appear to be involved in the patient outcome for those infected with CC30 strains, meaning this strain is killing people in a different way.