Transient exposure to a physiologically-relevant concentration of calcium confers tobramycin resistance upon sessile cells of Pseudomonas aeruginosa.
Sessile populations of a mucoid Pseudomonas aeruginosa isolate generated in M-56 medium of 'low' (0.02 mM) or 'high' (2.5 mM) Ca2+ were treated with tobramycin (250 micrograms.ml-1), as were biofilms exposed transiently to 'high' Ca2+ medium. Viability decreased by over 99.9% within 8 h in the 'low' and 'high' samples, while transient Ca2+ exposure was protective. Dispersed sessile bacteria were as tobramycin sensitive as planktonic bacteria.
Hoyle
B D
BD
Department of Biological Sciences, University of Calgary, Alberta, Canada.
Costerton
J W
JW
D002118:Calcium / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D014031:Tobramycin / Q000494:pharmacology*
D002118:Calcium; D014031:Tobramycin