Minimum inhibitory concentration (MIC) versus minimum biofilm eliminating concentration (MBEC) in evaluation of antibiotic sensitivity of gram-negative bacilli causing peritonitis.
OBJECTIVE
Minimum inhibitory concentration (MIC) and minimum biofilm eliminating concentration (MBEC) results were compared to determine changes in the pattern of antibiotic sensitivity of gram-negative bacilli from the planktonic to the biofilm phase of growth.


METHODS
The MIC and MBEC assays were conducted on stored isolates obtained from patients presenting with peritoneal dialysis-related gram-negative peritonitis with Escherichia coli or Pseudomonas.


RESULTS
The antibiotic sensitivities of planktonic organisms tested by the MIC assays were significantly higher than the antibiotic sensitivities of the same organisms in their biofilm state, as tested by the MBEC assays.


CONCLUSIONS
In their biofilm state, gram-negative bacteria are much less susceptible to antibiotics compared to their antibiotic susceptibility in the planktonic state.
Sepandj
Farshad
F
Department of Medicine, University of Calgary, Calgary, Alberta, Canada. fsepandj@shaw.ca
Ceri
Howard
H
Gibb
Allan
A
Read
Ronald
R
Olson
Merle
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010538:Peritonitis / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
D000900:Anti-Bacterial Agents