The lungs of cystic fibrosis patients are often colonized by the pathogen Pseudomonas aeruginosa, and the infection can be particularly difficult to treat. The bacterium's resistance to antibiotics seems to be linked to its propensity to grow in communities embedded in a protective sugar matrix or biofilm. Bacterial cells cocooned in this way can be up to 1,000 times more resistant to antibiotics than free-living cells.
Now the properties of a newly isolated mutant of P. aeruginosa outlined by George A. O'Toole and colleagues in Nature (Vol. 426, No. 6964, 20 Nov 03; pp. 306-310) suggest, however, that biofilms are not simply a diffusion barrier. The mutant gene codes for a glucan that binds specifically to the antibiotic tobramycin, holding it within the biofilm before it can reach its site of action.
This suggests that co-treatment, with an antibiotic and a compound that targets a specific glucan in the biofilm, might help to overcome antibiotic resistance.
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