Curious clues in war between bacteria in cystic fibrosis patients

Date:
August 8, 2020
Source:
University of North Carolina Health Care
Summary:
Several different kinds of bacteria can cause lung infections in
people with cystic fibrosis. Pseudomonas aeruginosa, which can
cause pneumonia, typically infects infants or young children and
persists for life, while Burkholderia cepacia complex species only
infect teenagers and adults.

Although Burkholderia infections are rare, when they do take hold,
they are deadly. Now, scientists have discovered a reason for this
pathogen's apparent age discrimination.



FULL STORY ========================================================================== Several different kinds of bacteria can cause lung infections in people
with cystic fibrosis (CF). Pseudomonas aeruginosa, which can cause
pneumonia, typically infects infants or young children and persists for
life, while Burkholderia cepacia complex species only infect teenagers
and adults. Although Burkholderia infections are rare, when they do
take hold, they are deadly. Now, UNC School of Medicine scientists led
by Peggy Cotter, PhD, professor in the UNC Department of Microbiology
and Immunology, have discovered a reason for this pathogen's apparent
age discrimination.


==========================================================================
This research, published in the journal Cell Host & Microbe, shows that
both Pseudomonas and Burkholderia use toxic weaponry, called Type VI
Secretion Systems (T6SS), to compete with and establish dominance over
each other. It's possible that scientists could target, or mimic, this
weaponry to defeat the bacteria before they cause irreparable harm to
lungs of patients.

Scientists have wondered for a long time why Burkholderia does not infect infants and young children. First author and former Cotter Lab graduate
student Andrew Perault, MPH, PhD, designed and conducted experiments to
show that Pseudomonas bacteria isolated from infants and young children
use their harpoon-like T6SS to fire toxins at, and kill, competitor
bacteria, including Burkholderia.

"This may be one of the reasons Burkholderia does not take root in young patients," Cotter said. "Andy showed that although Burkholderia also
produce T6SSs, they cannot effectively compete with Pseudomonas isolates
taken from young CF patients." However, as those Pseudomonas bacteria
adapt to living in the lungs of CF patients, they lose their ability to
produce T6SSs and to fight with Burkholderia. The Burkholderia, using
their own T6SSs, are then able to kill the Pseudomonas and establish
infection.

"We believe the findings of our study, at least in part, may explain
why Burkholderia infections are limited to older CF patients," Perault
said. "It appears that as at least some strains of Pseudomonas evolve
to persist in the CF lung, they also evolve to lose their T6SSs, and
hence their competitive edge over Burkholderia, which are then free to
colonize the respiratory tract." The scientists think the Burkholderia
T6SS is an important factor promoting the ability of these pathogens
to infect CF patients. Therefore, researchers could potentially develop therapeutics to target these secretion systems to prevent infections.

Moreover, assessing the T6SS potential of resident Pseudomonas populations within the CF respiratory tract may predict susceptibility of patients
to potentially fatal Burkholderia infections.


========================================================================== Story Source: Materials provided by
University_of_North_Carolina_Health_Care. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Andrew I. Perault, Courtney E. Chandler, David A. Rasko, Robert
K. Ernst,
Matthew C. Wolfgang, Peggy A. Cotter. Host Adaptation Predisposes
Pseudomonas aeruginosa to Type VI Secretion System-Mediated
Predation by the Burkholderia cepacia Complex. Cell Host & Microbe,
2020; DOI: 10.1016/j.chom.2020.06.019 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200808085752.htm

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