Antibiotic treatment duration for bloodstream infections in critically ill patients: a national survey of Canadian infectious diseases and critical care specialists

https://doi.org/10.1016/j.ijantimicag.2011.07.016Get rights and content

Abstract

An optimum duration of antibiotic therapy would eradicate infection whilst minimising adverse drug reactions, resistance and costs. However, there is a paucity of evidence guiding the duration of therapy for bloodstream infections. Canadian infectious diseases (ID) and critical care specialists were surveyed regarding their recommended antibiotic treatment durations for five common bacteraemic syndromes. A descriptive analysis was performed to assess: (i) practice heterogeneity; (ii) equipoise for a trial of shorter versus longer therapy; and (iii) the influence of pathogen and host characteristics on recommendations. In total, 172 clinicians responded to the survey (60% ID, 39% critical care and 1% combined specialists). For each syndrome, the most common recommendation was 14 days, yet the majority of respondents recommended durations of ≤10 days. Median durations were similar for each syndrome: central vascular catheter-related bloodstream infection, 10 ± 3.6 days; bacteraemic pneumonia, 10 ± 2.8 days; bacteraemic urinary tract infection, 10 ± 3.8 days; bacteraemic intra-abdominal infection, 10 ± 4.1 days; and bacteraemic skin and soft-tissue infection, 14 ± 3.2 days. Respondents recommended the longest durations for Staphylococcus aureus and the shortest durations for coagulase-negative staphylococci. Most respondents would not modify duration based on host characteristics or measures of clinical response. ID physicians recommended longer durations than critical care physicians for all five syndromes, but the majority of both specialist groups would enrol patients in a trial of shorter (7 day) versus longer (14 day) antibiotic therapy. In conclusion, significant practice variation exists amongst clinicians’ recommended durations of antibiotic treatment for bacteraemia. There is equipoise for a randomised trial comparing shorter versus longer courses of antibiotics for most bacteraemic syndromes and pathogens.

Introduction

Overuse of antibiotics in hospitals continues to drive antibiotic resistance [1]. It is estimated that 30–50% of antibiotic use in hospitals is unnecessary or inappropriate, and the most common explanation is excessive duration of treatment [2], [3]. With high prevailing antibiotic resistance rates and evidence that inadequate empirical coverage during the front-end of therapy is associated with higher patient mortality, it is difficult to minimise broad-spectrum antibiotic use when patients present with severe systemic infection [4], [5]. Therefore, the greatest potential benefit may lie in reducing unnecessary therapy at the back-end of treatment [5]. Indeed, emerging evidence suggests that shorter courses are as effective as longer courses for common outpatient infections ranging from sinusitis to cystitis [6]. A landmark study of ventilator-associated pneumonia demonstrated that short-course therapy (8 days) was equivalent to longer-course therapy (15 days) and has altered clinical practice for this severe Intensive Care Unit (ICU) infection [7].

In contrast, no useful evidence exists to guide treatment duration amongst the 15% of critically ill patients who develop bloodstream infection (BSI) [8]. A systematic review has identified no randomised controlled trials (RCTs) of durations of antibiotic therapy for adult patients with bacteraemia (Havey et al., unpublished data). In the absence of evidence, Infectious Diseases Society of America (IDSA) guidelines must rely on expert consensus in recommending 10–14 days of therapy for central vascular catheter-related bloodstream infection (CVC-BSI) [9]. Meanwhile, guidelines regarding the other common sources of BSI in intensive care (respiratory tract, urinary tract, soft tissue, and intra-abdominal infections) do not comment on whether the duration of treatment ought to be modified for patients with positive blood cultures [10], [11], [12], [13], [14].

In the context of this evidence vacuum, we conducted a nationwide survey of Canadian infectious diseases (ID) and critical care specialists to learn what durations of antibiotic therapy they typically recommend for common bacteraemic syndromes in critically ill patients. The objectives were three-fold: (i) to describe the extent of practice heterogeneity; (ii) to evaluate host, pathogen and prescriber factors influencing prescribed treatment durations; and (iii) to determine whether clinical equipoise exists to answer this question definitively through a RCT.

Section snippets

Study setting and population

During July 2010 to April 2011, a national practice survey was conducted amongst Canadian ID and critical care specialists regarding their recommended treatment durations for critically ill patients with BSI. Approval for the survey was granted by the research ethics board at Sunnybrook Health Sciences Centre, University of Toronto (Toronto, Canada).

Survey design

The survey consisted of five brief scenarios outlining common bacteraemic syndromes in the ICU: CVC-BSI; bacteraemic pneumonia; bacteraemic urinary

Characteristics of survey respondents

The overall initial response rate was low (24.0% from the AMMI Canada mail-out and 16.5% from the CCCS mail-out), but after subsequent electronic mail-outs and academic detailing a total of 172 clinicians responded to the survey, including 103 ID specialists (60%), 67 critical care specialists (39%) and 2 combined ID and critical care specialists (1%). The majority of these clinicians (140; 81%) reported practicing in academic institutions, including similar proportions of ID and critical care

Discussion

This national survey of Canadian ID and critical care specialists identified significant practice variation in the recommended duration of antibiotic treatment for bacteraemia; it established evidence of equipoise to justify a clinical trial to compare shorter- versus longer-course antibiotic therapy; and it characterised which syndrome, pathogen, host and prescriber factors influence the willingness of physicians to consider shorter-course therapy.

The most commonly recommended treatment

Acknowledgments

The authors would like to acknowledge the Association of Medical Microbiologists and Infectious Diseases (AMMI) Canada, the Canadian Critical Care Trials Group, and the Canadian Critical Care Society (CCCS) for graciously distributing the survey to Canadian ID and critical care specialists.

Funding: ND is supported by a Clinician Scientist Award from the Canadian Institutes of Health Research. RF is a Clinician Scientist of the Heart and Stroke Foundation. Additional funding for this study was

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