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Antimicrobial stewardship

Antimicrobial stewardship

What is Antimicrobial Stewardship?

Many diseases are caused by infections. Antimicrobials, like penicillin antibiotics, are used to treat infections. Antimicrobials are effective but not without the potential for harm. Overuse of antimicrobials, for example, can lead to drug resistance which means they are less effective in treating infections. Some antimicrobials can also cause serious adverse events (unintended harm) and need to be closely monitored and managed when they are used.

In order to ensure antimicrobials remain effective in treating infections and minimise adverse events when they are used, it is important to ensure antimicrobial treatment is appropriate

Antimicrobial stewardship is a broad umbrella term which includes various monitoring and improvement initiatives designed to ensure that the right antimicrobials are used, at the right time, for the right patient and in the right way. Antimicrobial stewardship is one the key strategies to minimise antimicrobial resistance[1].

What are we trying to achieve?

Our organisational aim is to optimise the use of antimicrobials and our antimicrobial stewards seek to ensure current antimicrobial use aligns with current best practice (as set out in the Health and Disability Service Standards - Infection Prevention and Control NZS 8134.3: 2008) [2] with a view to:

  • optimise clinical outcomes related to antimicrobial use;
  • minimise toxicity and other adverse events;
  • reduce the costs of health care for infections; and
  • limit the selection for antimicrobial resistant strains

What have we done?

As part of achieving our overall antimicrobial stewardship objectives we established a multi-disciplinary governance group, the Antimicrobial Stewardship Committee (ASC), to lead improvement at Waitemata DHB. Over the past year the group has overseen the following:

  1. Launch of a targeted campaign to safeguard patients when a group of high risk antibiotics (called aminoglycosides) are used, which included:
    • development of a standardised protocol to guide optimal aminoglycoside use, dosing and monitoring
    • staff education on how to better use aminoglycosides and the risks they should be vigilant of
    • introduction of policy, guidance and systems to reduce the instances of unnecessary prolonged use of aminoglycosides beyond 48 hours; which can be associated with kidney injury and hearing impairment
  2. Development of an initiative to reduce unnecessary complications from antibiotic use, such as C. difficile infections (CDI) that can occur. This has included:
    • undertaking detailed case reviews of identified incidents of CDI to better understand the contributory factors with a view to inform the improvement of existing systems
    • development of real-time routine surveillance system and clinician feedback to identify inappropriate antimicrobial prescribing practice in terms of choice, indication and duration of antibiotics. The purpose of this is to increase awareness and reduce the cases of hospital-onset healthcare associated CDI through antimicrobial stewardship
  3. Undertaking an evaluation of antimicrobial use to identify opportunities for reducing unnecessary costs which has included:
    • publishing antibiotic guidelines and provided staff education to improve prescribing practice
    • encouraging the use of oral formulation of drugs, rather than intravenously where appropriate

What have we achieved?

Over the past year, we have:

  • Reduced the instances of unnecessary prolonged use of a type of aminoglycoside called gentamicin beyond 48 hours from 11% to 5%


Baseline audit

Mar 2016 audit

Jun 2016 audit

% patients on gentamicin for >48hrs




  • Reduced unnecessary anti-microbial costs:
    Since the introduction of the ASC in September 2013, there has been a significant reduction in antimicrobial expenditure, with a 26% reduction in the yearly antimicrobial spend for 2015/2016 compared with 2012/2013. Antimicrobial expenditure was within budget for 2015/2016 despite a 7% reduction in the budget compared to the 2014/2015 financial year and a 17% reduction compared to 2012/2013.

Antimicrobial Spend per Occupied Bed
Antimicrobial Spend per Occupied Bed (Quarterly 2012-2016)

Where to from here?

Activities are still planned within these initiatives outlined above including:

  • Providing ongoing education to staff about best use of aminoglycosides
  • Development of a C.difficile Management Guideline, and initiating a formalised root cause analysis process with the aim of reducing HO-HCA CDI at Waitemata DHB
  • Continue to target opportunities for reducing unnecessary costs with antimicrobial use

  1. Practical Guide to Antimicrobial Stewardship In Hospitals
  2. NZ Health and Disability Standard (Infection Prevention and Control Standards) NZS 8134.3:2008
    "Acute care and surgical hospitals will have established and implemented policies and procedures for the use of antibiotics to promote the appropriate prudent prescribing in line with accepted guidelines. The service can seek guidance from clinical microbiologists or infectious disease physicians"