In Summary, for those who received both topical and systemic antibiotics:

Benefits in NNT

  • 75% saw no benefit
  • 6% were helped by being saved from death
  • 25% were helped by preventing one respiratory tract infection
  • 1 in 18 were helped (life saved)
  • 1 in 4 were helped (prevented one respiratory tract infection)

Harms in NNT

  • An unknown % were harmed by medication side effects/adverse reactions
  • An unknown number were harmed (medication side effects/adverse reactions)

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Source: Liberati A et al. Antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving intensive care. Cochrane Database Syst Rev. October, 2009.

de Jonge E et al. Effects of selective decontamination of digestive tract on mortality and acquisition of resistant bacteria in intensive care: a randomized controlled trial. Lancet. September, 2003.

Efficacy Endpoints: Mortality, Developing Respiratory Tract Infections (pneumonia or tracheobronchitis)

Harm Endpoints: Increasing resistant microbial strains in the ICU

Narrative: In the intensive care unit pneumonia is a common source of patient morbidity and mortality. The administration of prophylactic antibiotics has been proposed as a treatment regimen to help prevent such infections. This Cochrane Review includes 36 trials (n = 6914) that occurred in the ICU setting. These studies examined the use of prophylactic antibiotics, administered systemically, topically or in combination. One study of 934 patients (de Jonge et al. 2003) also looked for the emergence of any antibiotic resistant microorganisms that may have occurred during the 2-year trial period.

Administration of a combination of systemic and topical antibiotics yielded significant benefit when compared to the control group. There was an absolute reduction in mortality of 5.5%, or 1 in every 18 adults given a prophylactic antibiotic combination. There was also an absolute risk reduction of 25% in respiratory tract infections, or 1 in every 4 adults in the treatment group.
Given that the systemic review of 36 RCTs combined for a sample size of nearly 7000 patients, these results are impressive and should shape current treatment practices in the intensive care setting.

Caveats: Of the 17 studies included in this review, only two (de Jonge 2003, Kruger 2002) showed statistically significant mortality benefits. Furthermore, these two studies provide nearly 40% of the weight in the review’s final analysis. The remaining 15 trials were not adequately powered to detect clinically significant differences on an individual basis. Antibiotic regimens also differed among trials, as did some outcome definitions. However, the pooled analysis demonstrated a compelling overall benefit.

Despite the existence of multiple high-quality randomized controlled trials, this practice has not been widely adopted. The most commonly cited reason is concern for precipitating the emergence of resistant strains of microorganisms in the ICU setting. Unfortunately, there is only one study that examined this issue (de Jonge et al. 2003), involving nearly 1,000 subjects. While the study suggested no corresponding increase in resistance one study, no matter how well designed, cannot adequately alleviate all concerns regarding the use of prophylactic antibiotic regimens. Despite this, on the basis of a compelling mortality benefit it would seem appropriate to begin implementing this regimen into ICU treatment practices while advocating further study.

Author: Dan Runde, MD

Published/Updated: December 23, 2010

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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