Tetracycline rapidly reaches all the constituent cells of uropathogenic Escherichia coli biofilms.
We have developed a method for visualizing Escherichia coli cells that are exposed to tetracycline in a biofilm, based on a previous report that liposomes containing the E. coli TetR(B) protein fluoresce when exposed to this antibiotic. By our method, cells devoid of TetR(B) also exhibited tetracycline-dependent fluorescence. At 50 microg of tetracycline ml(-1), planktonic cells of a uropathogenic E. coli (UPEC) strain developed maximal fluorescence after 7.5 to 10 min of exposure. A similar behavior was exhibited by cells in a 24- or 48-h UPEC biofilm, as examined by confocal laser microscopy, regardless of whether they lined empty spaces or occupied densely packed regions. Further, a comparison of phase-contrast and fluorescent images of corresponding biofilm zones showed that all the cells fluoresced. Thus, all the biofilm cells were exposed to tetracycline and there were no pockets within the biofilm where the antibiotic failed to reach. It also appeared unlikely that niches of reduced exposure to the antibiotic existed within the biofilms.
Stone
G
G
Department of Microbiology and Immunology, Stanford University School of Medicine, 299 West Campus Drive, Stanford, CA 94305, USA.
Wood
P
P
Dixon
L
L
Keyhan
M
M
Matin
A
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D004058:Diffusion; D004926:Escherichia coli / Q000187:drug effects*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D005453:Fluorescence; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010957:Plasmids / Q000187:drug effects / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology*; D013753:Tetracycline Resistance / Q000235:genetics; D014466:Ultraviolet Rays; D014552:Urinary Tract Infections / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; C470187:TetR(B) protein, E coli; D013752:Tetracycline