Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions

Kolpen Mette, Cecilie F Appeldorff, Sarah Brandt, Nabi Mousavi, Kasper N Kragh, Sevtap Aydogan, Haleema A. Uppal, Thomas Bjarnsholt, Oana Ciofu, Niels Høiby, Peter Ø Jensen

36 Citationer (Scopus)


Tolerance towards antibiotics of Pseudomonas aeruginosa biofilms is recognized as a major cause of therapeutic failure of chronic lung infection in cystic fibrosis patients. This lung infection is characterized by antibiotic-tolerant biofilms in mucus with zones of O2 depletion mainly due to polymorphonuclear leukocytic activity. In contrast to the main types of bactericidal antibiotics, it has not been possible to establish an association between the bactericidal effects of colistin and the production of detectable levels of OH⋅ on several strains of planktonic P. aeruginosa. Therefore we propose that production of OH⋅ may not contribute significantly to the bactericidal activity of colistin on P. aeruginosa biofilm. Thus, we investigated the effect of colistin treatment on biofilm of wildtype PAO1, a catalase deficient mutant (ΔkatA) and a colistin resistant CF isolate cultured in microtiter plates in normoxic- or anoxic atmosphere with 1 mM nitrate. The killing of bacteria during colistin treatment was measured by CFU counts and the OH⋅ formation was measured by 3'-(p-hydroxylphenyl fluorescein) fluorescein (HPF) fluorescence. Validation of the assay was done by hydrogenperoxide treatment. OH⋅ formation was undetectable in aerobic PAO1 biofilms during 3 hours of colistin treatment. Interestingly, we demonstrate increased susceptibility of P. aeruginosa biofilms towards colistin during anaerobic conditions. In fact, the maximum enhancement of killing by anaerobic conditions exceeded 2 logs using 4 mg/L of colistin compared to killing at aerobic conditions.

TidsskriftPathogens and Disease
Sider (fra-til)ftv086
StatusUdgivet - 2016


Dyk ned i forskningsemnerne om 'Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions'. Sammen danner de et unikt fingeraftryk.