Introduction to ambulatory antimicrobial therapy

Ambulatory antimicrobial therapy (also known as outpatient parenteral antimicrobial therapy [OPAT] or hospital in the home [HITH]) refers to the use of antimicrobial drugs (usually parenteral antimicrobials) in a community setting as an alternative to care in hospital. There are differences across Australian states in funding and governance requirements for ambulatory antimicrobial therapy.

This topic aims to set a standard of care that applies to all patients receiving ambulatory antimicrobial therapy, regardless of how it is delivered. Governance is an important element of an ambulatory antimicrobial therapy program – see Governance of ambulatory antimicrobial therapy programsChapman, 2019.

The Hospital in the Home Society Australasia has developed a position statement that documents a definition of HITH, what the requirements are and how to measure outcomes.

Ambulatory antimicrobial therapy programs increase patient satisfaction, reduce the risk of hospital-acquired infections, and can reduce costs for hospitals. Expansion of these services has been enabled by the increasing availability of suitable antimicrobial preparations, and advances in vascular access and infusion device technology.

Note: The quality and safety of care provided by ambulatory antimicrobial therapy programs should not be inferior to hospital care.

The quality and safety of care provided to patients receiving ambulatory antimicrobial therapy should not be inferior to hospital care; if this is not possible, the patient should be managed in hospital.

For children, ambulatory antimicrobial therapy is administered by specialist paediatric programs, though usually not for children younger than 4 weeks of age. Most of the information in this topic also applies to children. Key differences in a paediatric program include:

  • Vascular access devices: Peripheral intravenous cannulae are generally not appropriate to use for continuous infusions or longer courses of ambulatory antimicrobial therapy in children; however, they may be used for intermittent bolus dosing or shorter courses where the infusion site can be protected adequately. General anaesthetic is usually required for insertion of central venous catheters (CVC), including peripherally inserted central catheter (PICC) lines.
  • Antimicrobial regimens: Different concentrations of antimicrobials may be required in children – seek expert advice as the stability data may differ from the advice this topic.

Further information on state-based hospital in the home (HITH) programs is available for Victoria, New South Wales and Queensland.

The Australian Commission on Safety and Quality in Health Care (ACSQHC) has developed an Antimicrobial Stewardship (AMS) in Australian Health Care book. Chapter 20 addresses antimicrobial stewardship strategies that can be used for outpatient parenteral antimicrobial therapy (OPAT), in hospital in the home (HITH), and other settings.

Figure 1. Governance of ambulatory antimicrobial therapy programs

An ambulatory antimicrobial therapy program should be part of a hospital’s clinical governance structure (or for non-hospital providers have similar governance structure in place). Key requirements are:

  • an accountable senior medical officer with overall responsibility for each episode of careChapman, 2019
  • regular medical review of each patient (usually at least once a week)
  • an effective monitoring system to detect and respond to clinical deterioration and complications in a timely manner
  • clear clinical endpoints of therapy for each patient, and medical follow-up at the end of therapy.
Antimicrobial stewardship (AMS) is a key feature of ambulatory antimicrobial therapy programs. AMS strategies that apply to patients receiving ambulatory antimicrobial therapy should the same as those that would apply in hospital, see Eight quality statements for effective antimicrobial stewardship in hospitals. Patients entering a program should have their antimicrobial plan reviewed to assess whether:
  • oral therapy would be sufficient
  • a narrower-spectrum antimicrobial is appropriate
  • the shortest duration of both intravenous and oral antimicrobial therapy is prescribed, taking into consideration the infection being treated and the patient’s clinical response.