From the beginning of antibiotic therapy, the length of prescription or days of therapy (DOT) was not evidence driven. Practice settled on 1 or more weeks, predicated on the incorrect belief that longer courses (well past clinical remission) might reduce the risk of relapse or of antibiotic resistance.[1,2] There is increasing evidence that shorter durations of antibiotic therapy are as effective as longer ones for many common infections.[3] In fact, extended courses that continue beyond resolution of the infection predictably increase the risk of antibiotic resistance. Here we report on the duration of therapy of community antibiotic prescriptions in British Columbia in the context of up-to-date guidelines from the Association of Medical Microbiology and Infectious Disease Canada.[4]

BC PharmaNet prescription data from our last prepandemic year (2019) were used to calculate the median duration (quartiles: Q1, Q3) of antibiotic prescriptions overall, by prescribing profession and drug. Physician prescriptions (~85% of total) were anonymously linked to MSP billing data to describe DOT distribution by indication.

In 2019, median DOT (Q1, Q3) per prescription in BC for all antibiotic prescriptions was 7 (7, 10) days, with the exception of naturopathic physicians where it was 14. Underscoring practice’s focus on 7 days as a standard measure, the median DOT per prescription was 7 days across all diagnoses. Distributions skewed further to the right (more long courses) for cellulitis, pyelonephritis, and acute bronchitis [Figure [17]].

The median DOT for community-acquired pneumonia was 7 days overall, but courses of 10 days duration remain common. Most treatments were prescribed for 7 to 10 days, except azithromycin, which was 5 days. Current guidance emphasizes the adequacy of 3 to 5 days of treatment, and this is not limited to long-acting macrolides.[5]

Cystitis also saw a 7-day median DOT over-all. For uncomplicated infections in women (the majority), current guidance recommends 5 days of nitrofurantoin, 3 days of cotrimoxazole, or 1 day of fosfomycin.[4] DOT for nitrofurantoin and other specific drugs often exceeded these recommendations.

Ciprofloxacin was the most commonly prescribed antibiotic for pyelonephritis, followed by cefixime. While median duration of treatment was appropriately 7 days, 10-day courses were almost as popular. While this is appropriate in complicated or slowly responding cases, it is more than is needed to resolve most pyelonephritis cases.[4]

For cellulitis, current guidance emphasizes 5 to 7 days of treatment.[4] Few prescribers in BC have adopted the shorter end of this range, and 10-day courses of cephalexin and clindamycin are common [Table [18]].

In BC, durations of antibiotic therapy observed during 2019 frequently exceeded the evidence-based recommendations. Prescribers must be able to exercise clinical judgment in managing complicated or atypical cases, but generally, should aspire to have population prescribing patterns that align with guidelines. The benefits include a reduced risk of immediate adverse effects and lower individual and population risk of selecting for resistant organisms. If we collectively update our prescribing practices to align with current evidence on duration of treatment, we can make a difference against antimicrobial resistance. As with much drug treatment, shorter is often better.
—Abdullah A. Mamun, MD
BC Centre for Disease Control
—Daniela Michel, MPH
BC Centre for Disease Control
—Max Xie, MSc
BC Centre for Disease Control
—Edith Blondel-Hill, MD
Interior Health Authority, Kelowna
—Säde Stenlund, MD
BC Centre for Disease Control
University of British Columbia
—Jennifer Grant, MD
University of British Columbia
Vancouver General Hospital
—Lynsey J. Hamilton, MSc
BC Centre for Disease Control
—David M. Patrick, MD
BC Centre for Disease Control
University of British Columbia

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This article is the opinion of the BC Centre for Disease Control and has not been peer reviewed by the BCMJ Editorial Board.

[19]

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License [19].

References

1.    Hanretty AM, Gallagher JC. Shortened courses of antibiotics for bacterial infections: A systematic review of randomized controlled trials. Pharmacotherapy 2018;38:674-687.

2.    WHO. Evidence based review on optimal duration of antibiotic therapy for bacterial infections to support antimicrobial stewardship recommendations. Accessed 24 January 2022. www.who.int/selection_medicines/committees/expert/22/applications/ABWG_optimal_duration_AB.pdf [20].

3.    Drekonja DM, Trautner B, Amundson C, et al. Effect of 7 vs 14 days of antibiotic therapy on resolution of symptoms among afebrile men with urinary tract infection: A randomized clinical trial. JAMA 2021;326:324-331.

4.    Grant J, Saux NL. Duration of antibiotic therapy for common infections. JAMMI 2021;6:181-197.

5.    Dinh A, Ropers J, Duran C, et al. Discontinuing β-lactam treatment after 3 days for patients with community-acquired pneumonia in non-critical care wards (PTC): A double-blind, randomised, placebo-controlled, non-inferiority trial. Lancet 2021;397(10280):1195-1203.