Treating HIV Encephalopathy with Antiretroviral Therapy: A Clinical Case Demonstrating the Success of HAART

among MRSA isolates from patients with persistent infections, as we and others [7] have found. With regard to the issue of “low” vancomycin trough serum levels and vancomycin response, raised by Howden et al. [8], the majority of patients in our study [3] were required to have vancomycin trough concentrations of 10 mg/mL. This serum trough concentration was chosen because it was the recommended trough concentration used in the phase III studies, in which vancomycin was a comparator to either quinupristin/dalfopristin or linezolid. Patients with endocarditis, an infected device (e.g., prosthetic device in knee), or a bone or joint infection were required to have a vancomycin trough concentration of 15 mg/mL. We have previously found lower 24-h AUC/MIC (vancomycin 24-h area under the concentration time curve divided by the MIC) values to be associated with vancomycin treatment failure in hospitalized patients with lower respiratory tract infections [9]. In our study [3], we would expect higher vancomycin MICs to be associated with lower trough-to-MIC ratios for patients with similar infections who had similar trough concentrations. In addition, if the 24-h AUC value was similar for all patients, the 24-h AUC/MIC values would be lower for patients with higher vancomycin MICs. However, appropriate levels for 24-h AUC determination were not obtained for all of the patients investigated. As stated above, patients with a variety of infection types were included in this investigation, and vancomycin trough levels were higher in patients with endocarditis, infected devices, or bone and joint infections, conditions which may be considered more “difficult to treat.” Even though vancomycin trough levels were higher in these patients, the majority of these “difficult-to-treat” infections were considered to be associated with vancomycin treatment failure. Howden et al. [8] are also curious about the geographic dispersion of the accessory gene regulator (agr) specificity group II isolates. We did not find the agr group II isolates to be from a specific US region, as shown in table 1 ( ). P p .386