Use of the E test to assess synergy of antibiotic combinations against isolates of Burkholderia cepacia-complex from patients with cystic fibrosis

Eur J Clin Microbiol Infect Dis. 2003 Jan;22(1):28-34. doi: 10.1007/s10096-002-0852-8. Epub 2003 Jan 25.

Abstract

Treatment of Burkholderia cepacia-complex infections in cystic fibrosis patients is problematic, since the microorganism is often resistant to most antimicrobial agents. In this study, the Epsilometer test, or E test, was used to assess the activity of antimicrobial combinations against Burkholderia cepacia-complex. In a preliminary evaluation, the E test was compared to the checkerboard method using 10 test organisms. Synergy testing by the E test was then performed on 131 clinical isolates of Burkholderia cepacia-complex using various combinations of antimicrobial agents. Agreement between the E test and the checkerboard method was 90%. The rate of resistance to individual agents ranged from 48% for meropenem to 100% for tobramycin, chloramphenicol, and rifampin. In 71.6%, 15.6%, and 12.6% of the test evaluations performed, the combinations tested resulted in additivity/indifference, synergism, and antagonism, respectively. The highest rates of synergy were observed with combinations of ciprofloxacin-piperacillin (44%), rifampin-ceftazidime (33%), chloramphenicol-ceftazidime (22%), cotrimoxazole-piperacillin/tazobactam (22%), and ciprofloxacin-ceftazidime (21%). Rates of antagonism for cotrimoxazole and chloramphenicol in combination with beta-lactam agents were higher than those observed for ciprofloxacin plus beta-lactam agents. These results suggest that the E test is a valuable and practical method to be considered for improving the identification of possible therapeutic options in cystic fibrosis patients infected with organisms belonging to the Burkholderia cepacia-complex.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriological Techniques*
  • Burkholderia Infections / drug therapy*
  • Burkholderia Infections / etiology
  • Burkholderia cepacia / drug effects*
  • Burkholderia cepacia / isolation & purification
  • Ceftazidime / pharmacology
  • Chi-Square Distribution
  • Child
  • Child, Preschool
  • Ciprofloxacin / pharmacology
  • Cystic Fibrosis / complications*
  • Cystic Fibrosis / drug therapy
  • Drug Resistance, Microbial
  • Drug Synergism
  • Drug Therapy, Combination / pharmacology*
  • Female
  • Humans
  • Lactams / pharmacology
  • Male
  • Microbial Sensitivity Tests / methods*
  • Piperacillin / pharmacology
  • Rifampin / pharmacology
  • Sensitivity and Specificity

Substances

  • Lactams
  • Ciprofloxacin
  • Ceftazidime
  • Rifampin
  • Piperacillin