title: Evaluation of E-Test for determination of antimicrobial MICs for Pseudomonas aeruginosa isolates from cystic fibrosis patients.
abstract: We determined the E-Test and National Committee for Clinical Laboratory Standards standardized agar dilution MICs of ceftazidime, ciprofloxacin, piperacillin, and tobramycin for Pseudomonas aeruginosa during tests of 100 rough and mucoid P. aeruginosa isolates from cystic fibrosis patients. The levels of agreement (+/- 1 log2 dilution) between quantitative E-Test and agar dilution MIC results were 80, 97, 73, and 89% for ceftazidime, ciprofloxacin, piperacillin, and tobramycin, respectively. Comparison of the results after converting the MIC data to qualitative categories (susceptible, intermediate, and resistant) yielded levels of agreement of 84, 96, 88, and 93% for the same agents, respectively. Of the 39 qualitative discrepancies, 36 were minor and 3 were very major. We conclude that use of the E-Test is easier and more practical than use of the agar dilution method for most laboratories and that the E-Test furnishes results which are at least as accurate as those obtained by the agar dilution method. However, the higher cost of the E-Test method would likely discourage most laboratories from selecting it over disk diffusion for routine antimicrobial susceptibility testing of P. aeruginosa isolates from cystic fibrosis patients.
authors.affiliation: Department of Pathology, George Washington University Medical Center, Washington, DC 20037, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Marley
authors.forename: C
authors.initials: C
authors.lastname: Mohla
authors.forename: J M
authors.initials: JM
authors.lastname: Campos
mesh_terms: D003550:Cystic Fibrosis / Q000150:complications* / Q000382:microbiology*; D004352:Drug Resistance, Microbial; D005069:Evaluation Studies as Topic; D006801:Humans; D008171:Lung Diseases / Q000150:complications* / Q000188:drug therapy / Q000382:microbiology*; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D011552:Pseudomonas Infections / Q000150:complications* / Q000188:drug therapy / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification