A potential way of killing persistent bacterial infections like those common to people with cystic fibrosis (CF) — using nutrient channels that may exist within bacterial communities to carry antibiotics — is suggested by a research team at the University of Strathclyde in Glasgow.
Their study, “Intra-colony channels in E. coli function as a nutrient uptake system,” was published in The ISME Journal: Multidisciplinary Journal of Microbial Ecology.
Lung infections often trouble CF patients, and bacteria that cause them can form communities called biofilms. This catch-all term refers to microorganisms that attach to a surface and form a distinct and complex community that is more resistant to treatment.
Researchers estimate that 80% of persistent bacterial infections, including those found in CF, are caused by biofilms and cannot be easily eliminated by antibiotics.
To understand biofilms in more detail, the researchers analyzed Escherichia coli (E. coli) bacteria and the internal architecture of their biofilms.
They used a new, state-of-the-art microscope called Mesolens, which they report provides a wide field of view and very high resolution. This microscope allowed them to capture 3D images of individual E. coli bacteria within the context of an entire biofilm community.
“By using the Mesolens we have been able to shine a light on biofilm architecture and visualise them like never before,” Liam Rooney, PhD, the study’s lead author, said in a press release.
E. coli bacteria were seen, reportedly for a first time, to establish a network of channels to transport nutrients throughout its biofilms.
Researchers suggested that this network — if found to be common within bacterial biofilms — could be exploited from a therapeutic perspective. That is, medications could take advantage of this transport network, with bacteria carrying antibiotics that might clear persistent infections instead of food.
“What we discovered is a network of nutrient-transporting channels that are formed when bacteria grow in large communities, and this could be used to kill bacteria more quickly by tricking the bacteria into transporting drugs through the channels instead of food,” Rooney said.
Current use of antibiotics against bacterial biofilms attack them from the outside, with limited success. Antibiotics are not particularly effective at penetrating these biofilms, in part because the structures have a protective, dome-like surface.
By targeting the transport network, the research team believes antibiotics would be much more efficient.
The problem with using antibiotics against a biofilm dome is that “antibiotics aren’t really penetrating into it. This then leads to persistence of the infection and then development of antimicrobial resistance, which is a major public health issue,” Rooney said.
Having “found a secret route into the biofilm from underneath … potentially we can get the drugs in under the dome to kill the bacteria quicker and more effectively,” he added.
The team believes that its findings, should channels be found in other types of bacterial biofilms besides those with E. coli, could have major implications for the design of new antibiotic treatments, especially for CF patients.
“These channels potentially offer a new route for the delivery of dispersal agents for antimicrobial drugs to biofilms, ultimately lowering their impact on public health and industry,” the researchers wrote.
These researchers are planning further studies into these nutrient channels, including how widely they exist in biofilms, likely using the Mesolens microscope.
“Aside from identifying and characterising intra-colony channels, this study has established the Mesolens as a much needed and powerful tool for studying microbial communities,” they wrote.
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