Clues to Why Burkholderia cepacia Only Infects Teenage and Adult Cystic Fibrosis Patients, While Pseudomonas auriginosa Infects Infants or Young Children with CF and Persists for Life; Type VI Secretion Systems (T6SS) Likely Play Key Role

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 online on August 4, 2020, in 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. The article is titled “Host Adaptation Predisposes Pseudomonas aeruginosa to Type VI Secretion System-Mediated Predation by the Burkholderia cepacia Complex.” 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, competing bacteria, including Burkholderia. "This may be one of the reasons Burkholderia does not take root in young patients," Dr. Cotter said.
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