Prescribing Antimicrobial Drugs for Acute Gastroenteritis, Primary Care, Australia, 2013–2018

Prescriptions for 6.8% of cases suggests a need for greater antimicrobial stewardship.

DOI: https://doi.org/10.3201/eid2705.203692 In support of improving patient care, this activity has been planned and implemented by Medscape, LLC and Emerging Infectious Diseases. Medscape, LLC is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.
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All other clinicians completing this activity will be issued a certificate of participation. To participate in this journal CME activity: (1) review the learning objectives and author disclosures; (2) study the education content; (3) take the post-test with a 75% minimum passing score and complete the evaluation at http://www.medscape.org/journal/eid; and (4) view/print certificate. For CME questions, see page 1551.  [2]) were affected, and ≈1.1 million of these persons sought care at a general practice (3,4). The most common cause of acute gastroenteritis is viral infection; therefore, antimicrobial drugs are not routinely recommended (5-7). Even for some common bacterial causes of acute gastroenteritis (e.g., nontyphoidal Salmonella and Campylobacter infections), antimicrobial therapy is not required for most patients because these infections are usually self-limiting (8).
Overuse of antimicrobial drugs for treating upper respiratory tract infections (mostly caused by viruses) has been well described (9,10) but not as much for acute gastroenteritis (11). Knowing the extent and pattern of antimicrobial drug use for acute gastroenteritis can help determine whether interventions to improve antimicrobial drug use for this specifi c clinical scenario are warranted.
We examined prescription of antimicrobial drugs for acute gastroenteritis in primary care practice in Australia during 2013-2018. The study was approved by the MedicineInsight Independent External Data Governance Committee (reference no. 2019-030: December 23, 2019) and the University of New South Wales Human Research Ethics Committee (no. HC190886).

The Study
We extracted clinical encounters for cases (including multiple episodes/patient) of acute gastroenteritis, nontyphoidal Salmonella infection, and Campylobacter infection recorded by MedicineInsight, a national primary healthcare database in Australia (https://www. nps.org.au/medicine-insight) during 2013-2018 and examined whether an antimicrobial drug was prescribed on the day of diagnosis (Appendix, https:// wwwnc.cdc.gov/EID/article/27/5/20-3692-App1. pdf). Antimicrobial drugs were prescribed for 6.8% Antimicrobial drug prescriptions for acute gastroenteritis increased with patient age (<10 years, 3.8%; >65 years, 13.7%) ( Table 1). Antimicrobial drugs were more likely to be prescribed for those with than without the following: fever or no temperature measurement, a requested fecal sample test, underlying conditions, or a record of bacterial or parasitic infection. Antimicrobial drugs were less likely to be prescribed for those with a record of viral infection. Prescribing also differed by practice remoteness; prescribing was higher in practices in more remote areas than in cities. During the study period, the trend toward antimicrobial drug prescribing decreased from 7.8% to 5.8% (p<0.001). Similar fi ndings were observed for children <10 years of age (Appendix Table 1).
For patients with nontyphoidal Salmonella infection (Appendix Table 2), prescriptions for antimicrobial drugs were more likely for those 30-49 than those <10 years of age (41.7% vs. 34.1%; p = 0.02) and in practices in outer regional or remote areas than in cities. Trend analysis of antimicrobial drug prescriptions for patients with nontyphoidal Salmonella infection suggested a signifi cant reduction; absolute reduction was 11.4% (from 42.1% in 2013 to 30.7% in 2018; p = 0.01). For patients with Campylobacter infection (Appendix Table 3), antimicrobial drugs were more likely to be prescribed for female than male patients (56.8% vs. 51.7%; p = 0.02). We observed no signifi cant reduction in antimicrobial drug prescriptions for patients with Campylobacter infection (55.8% to 57.1%; p = 0.81).
Of the 6,652 acute gastroenteritis cases for which antimicrobial drugs were prescribed, a reason was recorded for 42.9% (2, was nitroimidazoles (41.6% of total; Table 2), of which metronidazole accounted for the most prescriptions (24.7% of total; Appendix Table 4).

Conclusions
In this large study of patient clinical encounters in general practices in Australia, we found that antimicrobial drugs were prescribed for 6.8% of all cases of acute gastroenteritis but for 35.7% of nontyphoidal Salmonella infections and 54.1% of Campylobacter infections. Over the 6-year study period, the absolute proportion of cases for which antimicrobial drugs were prescribed for acute gastroenteritis decreased by 2%.
Of the few studies reporting on how often antimicrobial drugs are prescribed for acute gastroenteritis, estimates range from 8.5% of 2,089 cases in a sentinel surveillance sample from primary care in Switzerland in 2014 (12) to 65% in a survey of 237 physicians in China in 2012 (13). Our results were most similar to the estimates reported from the Switzerland study, which also found that antimicrobial drugs were more likely to be prescribed for older patients and those with fever (12).
In Australia, treatment guidelines recommend that empirical prescription of antimicrobial drugs is of no benefit for acute gastroenteritis and is indicated only for patients with manifestations of severe disease, those who are immunocompromised, returned travelers of all ages, or children in whom systemic bacterial infection is suspected (7). Our results suggest that general practitioners are more likely to  adhere to guidelines and that antimicrobial drugs are more likely to be prescribed for patients who are older, those with underlying conditions, and those with systemic symptoms (e.g., fever). However, the substantial numbers of patients without these indications for whom antimicrobial drugs were still prescribed suggests overuse of antimicrobial drugs for acute gastroenteritis. Reassuringly, we did find reduced antimicrobial drug prescriptions for acute gastroenteritis during the 6-year study period. This finding is consistent with that of an earlier study that used the same dataset and found an overall reduction in the proportion of patients for whom systemic antimicrobial drugs were prescribed: from 31.7% in 2015 to 26% in 2017 (14). This reduction has been attributed to a series of antimicrobial stewardship programs implemented during 2009-2014, which included educational and advertising campaigns aimed at general practitioners and consumers (15). Our results suggest that these antimicrobial stewardship programs may have reduced antimicrobial drug prescriptions for acute gastroenteritis.
Given the estimated 1.1 million cases of acute gastroenteritis seen in general practices in Australia annually (3), we estimate that nationwide ≈74,000 antimicrobial drugs are prescribed for acute gastroenteritis every year. Because most of these drugs are probably unnecessary, our findings highlight the need for greater antimicrobial stewardship to support management of infectious gastroenteritis in primary care.