Frequency of Reduced Vancomycin Susceptibility and Heterogeneous Subpopulation in Persistent or Recurrent Methicillin-Resistant Staphylococcus aureus Bacteremia

Vancomycin susceptibility was checked in isolates from initial and final blood samples obtained from 22 patients with persistent or recurrent methicillin-resistant Staphylococcus aureus bacteremia. The minimum inhibitory concentration of vancomycin was determined using Etest and found to have increased in 2 pairs of isolates, and results of screening in 4 µg vancomycin and a modified population analysis profile suggested heteroresistance in 3 isolates (13.6%). Heteroresistance is not a common cause of persistent or recurrent bacteremia.