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Publication Q&A: Creation of a Cystic Fibrosis-Specific Antibiotic Spectrum Index as an Antimicrobial Stewardship Initiative

Test vials sit on a table

March 2024 – Dr. Jonathan Cogen, principal investigator at Seattle Children’s Research Institute’s Center for Respiratory Biology and Therapeutics, in partnership with other Seattle Children’s researchers, aims to improve treatment for people with cystic fibrosis (CF) using an expanded antibiotic spectrum index (ASI) tool. The tool enables future CF research studies to access more inclusive data to optimize antibiotic selection, with the goal of better outcomes for adults and children with cystic fibrosis.

Read the study online (currently in press) in the Journal of Cystic Fibrosis.

What are the significant findings in this paper?

Antibiotics are routinely included in the treatment of CF-related pulmonary exacerbations, despite limited data to guide optimal and individualized prescription. Although antibiotic use for people with CF has shown improved clinical outcomes, there are growing concerns related to treatment resistance and adverse antibiotic-related effects on patients.

Antibiotic stewardship — which emphasizes antimicrobial choice, dose and treatment duration to improve outcomes and decrease risk for toxicity and side effects — has recently become a focus in the care of patients with CF. The antibiotic spectrum index (ASI) is a tool that classifies antibiotics based on microorganism activity and was developed to assess the relative breadth of antibiotic spectrum as an antimicrobial stewardship metric.

To better include patients with CF who may prospectively need antibiotic treatment, we created an expanded ASI that increases the original ASI to include bacterial microorganisms common to CF airway infections. We included 62 antibiotics, along with 17 microorganisms, in the creation of the CF-specific ASI (the original score included 49 antibiotics and 14 microorganisms).

What are the broad implications of this research?

Antibiotics are frequently utilized in the care of people with CF, yet optimal antibiotic strategies are unknown. There are growing concerns about antibiotic overuse among people with CF, and thus studies evaluating antibiotic approaches to CF treatment are essential.

The creation and application of a CF-focused ASI into CF research and antibiotic stewardship programs can help to optimize antibiotic benefits, minimize harms and allow for increased sustainability of antibiotic use in CF.

What are the next steps and long-term goals for this research?

Population-specific antimicrobial scoring indices represent an important innovation in the management of patients with CF, given their frequent and prolonged exposure to antibiotics, unique respiratory biology and potential antibiotic harm over their lifetime.

We intend to use this CF-specific ASI in future studies that aim to determine optimal antibiotic utilization patterns among people with CF. We are currently completing an analysis that uses this ASI approach.

Seattle Children’s contributing authors:

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