People with cystic fibrosis may experience more severe bacterial infections if they carry a certain type of virus 鈥� even though the virus actually targets bacteria. The so-called filamentous bacteriophage seems to prevent antibiotics from reaching the bacteria, making infections harder to treat.
Cystic fibrosis is a genetic disease that leads to the build-up of thick mucus in organs including the lungs. The mucus can provide a breeding ground for harmful bacteria, such as Pseudomonas aeruginosa.
Elizabeth Burgener at Stanford University, California, and her colleagues tested mucus samples taken from 58 people who have cystic fibrosis and a P. aeruginosa infection. They found that 21 of them 鈥� 36 per cent 鈥� carried bacteria-infecting viruses called filamentous bacteriophages.
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鈥淲e know bacteriophages exist everywhere,鈥� says Burgener, but they are often overlooked by health researchers because they don鈥檛 target human cells.
What鈥檚 more, those who carried the virus had significantly more P. aeruginosa in their mucus than non-carriers. And some of this P. aeruginosa seemed to be resistant to three of the common antibiotics used to treat such infections.
Filamentous bacteriophages are known to be able to bind to other molecules in the mucus, such as DNA and proteins, to form a very viscous film. The film serves as a shield that antibiotics can鈥檛 penetrate, says Burgener, which may be why the P. aeruginosa appears drug-resistant in the presence of the virus.
鈥淭here is a need to take this bacteriophage more seriously,鈥� says Joanna Goldberg at Emory University in Georgia. Antibiotic resistance is a major concern for people with cystic fibrosis because they are left with fewer options to treat life-threatening infections. Goldberg suggests doctors may need to test for the presence of the virus before deciding which type of antibiotics to use.
The new findings also suggest a new therapeutic approach, Burgener says. 鈥淚f this virus is making Pseudomonas strong, we can design treatments that attach and block it to clear the infection,鈥� she says.
Science Translational Medicine
