Swathes of antibiotic-resistant bacteria known as biofilms frequently infect the lungs of patients suffering cystic fibrosis (CF), and are often fatal. In this week’s Nature (Vol. 416, No. 6882, pp. 740-743, dated 18 April 2002), Eliana Drenkard and Frederick Ausubel of Harvard Medical School in Boston suggest how the normally innocuous bacteria, Pseudomonas aeruginosa, change into a more dangerous state.
They show that natural variations in the bacteria enable some of them to 'phase-shift' into a form that can grow in the presence of antibiotics and which is adept at forming biofilms. The two properties appear to be switched on together.
Conditions present in the lungs of CF patients means that there is a small population of bacteria in this naturally antibiotic-resistant form, suggests Ausubel. These survive drug treatment and proliferate into biofilms, which are themselves antibiotic-resistant.
Importantly, the researchers identified a protein that regulates the phase-shift. A drug that targets this protein might shift the bacteria back into their antibiotic-susceptible state, says George O’Toole of Dartmouth Medical School in New Hampshire, in an accompanying News and Views article.
Frederick M. Ausubel
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