Randomized trial of biofilm testing to select antibiotics for cystic fibrosis airway infection

Samuel M. Moskowitz, Julia C. Emerson, Sharon McNamara, Richard D. Shell, David M. Orenstein, Daniel Rosenbluth, Marcia F. Katz, Richard Ahrens, Douglas Hornick, Patricia M. Joseph, Ronald L. Gibson, Moira L. Aitken, Wade W. Benton, Jane L. Burns

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Rationale In cystic fibrosis (CF), conventional antibiotic susceptibility results correlate poorly with clinical outcomes. We hypothesized that biofilm testing would more accurately reflect the susceptibilities of bacteria infecting CF airways. Methods A multicenter randomized pilot trial was conducted to assess the efficacy and safety of using biofilm susceptibility testing of Pseudomonas aeruginosa sputum isolates to guide antibiotic regimens for chronic airway infections in clinically stable adolescent and adult CF patients. Thirty-nine participants were randomized to biofilm or conventional treatment groups; 14-day courses of two antibiotics were selected according to an activity-based algorithm using the corresponding susceptibility results. Results Of the agents tested, meropenem was most active against biofilm-grown bacteria, and was included in regimens for about half of each study group. For 19 of 39 randomized participants, randomization to the other study group would not have changed the antibiotic classes of the assigned regimen. Study groups were comparable at baseline, and had similar mean decreases in bacterial density, measured in log 10 colony forming units per gram of sputum (biofilm, -2.94 [SD 2.83] vs. conventional, -3.27 [SD 3.09]), and mean increases in forced expiratory volume in 1 sec, measured in liters (0.18 [SD 0.20] vs. 0.12 [SD 0.22]). Conclusions: In this pilot study, antibiotic regimens based on biofilm testing did not differ significantly from regimens based on conventional testing in terms of microbiological and clinical responses. The predictive value of biofilm testing may nonetheless warrant evaluation in an adequately powered clinical trial in younger CF patients or those experiencing acute pulmonary exacerbation.

Original languageEnglish
Pages (from-to)184-192
Number of pages9
JournalPediatric Pulmonology
Issue number2
StatePublished - Feb 2011


  • Pseudomonas aeruginosa
  • antibiotic resistance
  • antibiotic susceptibility testing
  • broth microdilution testing
  • inhibitory quotient
  • intravenous antibiotics
  • lung function
  • sputum bacterial density

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    Moskowitz, S. M., Emerson, J. C., McNamara, S., Shell, R. D., Orenstein, D. M., Rosenbluth, D., Katz, M. F., Ahrens, R., Hornick, D., Joseph, P. M., Gibson, R. L., Aitken, M. L., Benton, W. W., & Burns, J. L. (2011). Randomized trial of biofilm testing to select antibiotics for cystic fibrosis airway infection. Pediatric Pulmonology, 46(2), 184-192. https://doi.org/10.1002/ppul.21350