Why Sequence Staphylococcus aureus VISA Strains?
The purpose of this sequencing project is to understand the genetic basis of a drug resistance mechanism as it emerges in the in-vivo environment under the selective pressure of the antimicrobial agent vancomycin. The proposal involves sequencing a pair of isogenic methicillin-resistant Staphylococcus aureus (MRSA) strains that were recently recovered from a patient undergoing extensive chemotherapy with vancomycin. The chronologically earliest isolate (JH1), recovered before the start of vancomycin therapy, is susceptible to vancomycin, and the “latest” isolate (JH9), recovered shortly before the death of the patient, has an increased vancomycin resistance. The range of change in antibiotic susceptibility and the altered physiological and biochemical properties of the strains indicate that strain JH9 represents the so-called VISA-type vancomycin resistance, which appeared in clinical specimens of MRSA in several countries during the last decade. Several types of tests indicate that th