M any terms have been used to describe the delivery of antimicrobials (antiviral, antifungal, or antibacterial agents) to patients in the outpatient setting through the parenteral (ie, intravenous, intramuscular, or subcutaneous) route, including outpatient intravenous antimicrobial therapy (OPIVAT), community-based parenteral anti-infective therapy (CoPAT), hospital at home, home intravenous antimicrobial therapy (HIAT), and outpatient parenteral antimicrobial therapy (OPAT) [1–6]. The latter term, OPAT, is the most widely used in the United States. It broadly refers to the parenteral administration of at least two doses of an antimicrobial to a patient on two different days without an intervening hospitalization [1]. OPAT arose from the recognition that some infectious diseases will require management with parenteral therapy, although the patient may not require hospitalization [7]. In 1974, Rucker and Harrison [8] used antibiotics intravenously for the management of pulmonary infections in children with cystic fibrosis in the outpatient setting. Subsequently, in 1978 Antoniskis and colleagues [9] described the first use of self-administered intravenous antibiotics in adult outpatients. Since then, many of the standard techniques of infusion therapy that were previously performed exclusively in the hospital setting have been introduced into the outpatient arena. An estimated 1 in 1000 Americans use OPAT annually and more than 250,000 OPAT courses are administered in the United States every year. The use of OPAT has been increasing at an estimated rate of 10% per annum in the past decade [1,3,10]. OPAT is considered safe, therapeutically effective, and economical [1,6,7,11]. It offers increased comfort and convenience in appropriately selected patients and provides one approach for cost containment, because hospitalization generally represents the most costly aspect of patient care [6,12–16]. OPAT has become a popular alternative that replaces or shortens hospital admissions. Many investigators, from various countries, reported the cost of