Outpatient ertapenem therapy in an ESBL-high-prevalence area: an efficacy, safety, and cost study Arturo Ortiz-Álvarez,1 Mónica A Delgado-Ramírez,1 Montserrat Cuevas-Zúñiga,1 Teresa Hernández-Carrera,1 David Moncada Barrón,2 Daniel Aguilar Zapata,1 Rafael R Valdez Vázquez,1 Juan Pablo Ramírez-Hinojosa,1 Ana Patricia Rodríguez-Zulueta1 1Department of Infectious Disease, Hospital General Dr. Manuel GEA González, Mexico City, Mexico; 2Microbiology Laboratory, Hospital General Dr. Manuel GEA González, Mexico City, Mexico Introduction: Outpatient parenteral antimicrobial therapy is a safe, effective, and convenient way of administering antimicrobials for a wide variety of infections. So far there are no reports on the efficacy of outpatient antimicrobial therapy in Mexico. Our objective was to determine the outcomes, safety, and cost of outpatient ertapenem therapy (OET) in our hospital. Patients and methods: A case series of 99 patients that received intravenous OET was conducted. The primary outcomes were clinical cure, relapse, and recurrence of infection. Results: Of the 99 patients who received OET the most common diagnosis was urinary tract infection in 56%. Extended-spectrum-β-lactamase-producing Enterobacteriaceae caused 67% of infections in our population. Ninety-seven percent of the patients were cured at the completion of OET. One patient presented relapse 12 days after the end of OET; two patients presented recurrence, one with skin and soft tissue infection and one with pyelonephritis at days 35 and 34, respectively, after the end of OET. Three patients were readmitted after OET, one with an episode of phlebitis, one with recurrence, and one with relapse. A case of non-Clostridium difficile-associated diarrhea was observed. The intravascular line complications observed during OET were phlebitis in two patients. Conclusion: In our hospital, the OET was found to be effective, safe, and cost-saving when compared to inpatient care. Keywords: OPAT, ESBL, ertapenem