A new study has found that infection was present in only half of the 378 adult patients who were prescribed antibiotics within the first two days of discharge post-surgery at Auckland City Hospital in 2013.

For one-third of the remaining patients, the use of antibiotics was inappropriate, and for the rest (13.8 per cent) the reason for use was not assessable and may have been inappropriate, concluded the researchers.

Antimicrobial resistance a global problem

Antimicrobial resistance (AMR) is a growing issue that threatens the effective treatment and prevention of infections worldwide. New Zealand has seen a dramatic rise in AMR over the recent years and there is a push locally and globally to reduce it. One of the ways of doing this is to discourage healthcare professionals from using antibiotics inappropriately.

“Given the growing problem of antibiotic resistance globally,” the researchers wrote, “it is important now more than ever to take action to reduce the use of inappropriate and unnecessary antibiotics.”

“This study demonstrates that a significant proportion of antibiotics dispensed to patients discharged following surgery are inappropriate and there is need for enhanced antimicrobial stewardship in this area.”

In an audit of hospital records, the researchers found that antibiotics were prescribed for an established infection (infection present on admission or any healthcare-associated infection) in 172 patients (45.5 per cent), as empiric therapy (defined as the use of an antimicrobial, in the absence of a definite diagnosis or evidence of infection to support this decision) in 100 patients (26.4 per cent), and as prolonged surgical antimicrobial prophylaxis in 41 patients (10.8 per cent).

How is ‘appropriateness’ assessed?

Researchers used the Australian National Antimicrobial Prescribing Survey guideline to assist with assessing appropriate prescribing – antibiotic use for an established infection was considered appropriate.

Antibiotic use as prolonged surgical antimicrobial prophylaxis (SAP) or without a documented indication was considered ‘inappropriate’, with the authors noting that the use of prolonged SAP was most notable among the ORL, general surgery and urology services.

Empiric therapy, which accounted for a quarter of all antibiotic prescriptions, was categorised as ‘appropriate’ if it was in accordance with local antibiotic guidelines or if there was a clearly defined clinical indication, such as documentation in the medical record of signs and symptoms of local infection or recurrent urinary tract infection prophylaxis. This was true in only 85 per cent of cases. Nearly all prescriptions given empirically were given for inappropriate (42 per cent) or not assessable (50 per cent) reasons.

Empiric therapy was categorised as ‘not assessable’ if there was limited clinical and laboratory evidence to support infection and ‘inappropriate’ if there was no clinical or laboratory evidence to support infection, or if antibiotic use was not consistent with local antibiotic guidelines.

Use of empiric antibiotics was particularly notable in the orthopaedic service, wrote the authors, and involved patients with traumatic injuries such as open fractures or wounds, lacerations and penetrating injuries, for whom pre-emptive antibiotics were continued for extended durations.

“Careful evaluation and classification of wounds could direct appropriate antibiotic therapy and reduce overuse of antibiotics.”

Worldwide, antimicrobial stewardship programmes aim to optimise antimicrobial use in order to lessen the impact of inappropriate use on patients and health systems. New Zealand launched its Antimicrobial Resistance Action Plan last year. Visit for more information.

The study was undertaken collaboratively by Auckland City Hospital’s Mary De Almeida, Joshua Freeman, Eamon Duffy and Sally Roberts, and Catherine Gerrard of the Health Quality & Safety Commission.

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