Treatment of vancomycin-resistant Enterococcus with quinupristin/dalfopristin and high-dose ampicillin

OBJECTIVE: To report the successful treatment of vancomycin-resistant Enterococcus (VRE) bacteremia using the combination of quinupristin/dalfopristin and high-dose ampicillin. CASE SUMMARY: A 38-year-old African American woman with relapsed acute myeloid leukemia and neutropenic fever developed VRE bacteremia following 3 successive courses of vancomycin for methicillin-resistant staphylococcal infections. Treatment with linezolid was initiated; however, after 9 days of therapy, blood cultures continued to reveal VRE and the patient became febrile. The patient was subsequently switched to quinupristin/dalfopristin and high-dose ampicillin. The fever resolved and all subsequent blood cultures were negative after the initiation of combination therapy. DISCUSSION: The emergence of VRE infections presents a treatment challenge in immunocompromised patients. When treating VRE infections in this patient population, the effectiveness of linezolid and quinupristin/dalfopristin is limited by their bacteriostatic activity when used as monotherapy. Recent in vitro data suggest synergistic activity with quinupristin/dalfopristin when used in combination with other antimicrobials in selected isolates of VRE. CONCLUSIONS: Persistent VRE bacteremia was successfully treated in this neutropenic patient using the combination of high-dose ampicillin and quinupristin/dalfopristin. Case reports and in vitro data suggest that concomitant therapy with high-dose ampicillin may be an effective treatment alternative for VRE infections not responding to standard therapy.