<i>Pseudomonas aeruginosa</i> is an opportunistic pathogenic bacterium involved in many human infections, including pneumonia, diabetic foot ulcers, and ventilator-associated pneumonia. <i>P. aeruginosa</i> cells usually undergo mucoid conversion during chronic lung infection in patients with cystic fibrosis (CF) and resist destruction by polymorphonuclear leukocytes (PMNs), which release free oxygen radicals (ROS), such as H<sub>2</sub>O<sub>2</sub>. PMNs are the main leucocytes in the CF sputum of patients who are infected with <i>P. aeruginosa</i>, which usually forms biofilms. Here, we report that PMNs or H<sub>2</sub>O<sub>2</sub> can promote biofilm formation by mucoid <i>P. aeruginosa</i> FRD1 with the use of the hanging-peg method. The mucoid strain infecting CF patients overproduces alginate. In this study, PMNs and H<sub>2</sub>O<sub>2</sub> promoted alginate production, and biofilms treated with PMNs or H<sub>2</sub>O<sub>2</sub> exhibited higher expression of alginate genes. Additionally, PMNs increased the activity of GDP-mannose dehydrogenase, which is the key enzyme in alginate biosynthesis. Our results demonstrate that PMNs or H<sub>2</sub>O<sub>2</sub> can enhance mucoid <i>P. aeruginosa</i> biofilms.
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The Involvement of Cell-to-Cell Signals in the Development of a Bacterial Biofilm
David G. Davies, Matthew R. Parsek, James P. Pearson et al. · Science · 1998 · 3.4K citations