Whole-Genome Sequencing of Staphylococcus aureus Strain RN4220, a Key Laboratory Strain Used in Virulence Research, Identifies Mutations That Affect Not Only Virulence Factors but Also the Fitness of the Strain

Staphylococcus aureus RN4220, a cloning intermediate, is sometimes used in virulence, resistance, and metabolic studies. Using whole-genome sequencing, we showed that RN4220 differs from NCTC8325 and contains a number of genetic polymorphisms that affect both virulence and general fitness, implying a need for caution in using this strain for such studies.