The analysis of the effect of niclosamide in the 42 las- and pyocyanin-proficient isolates showed that pyocyanin production was unaffected or only marginally affected by niclosamide in the majority of isolates, with residual pyocyanin levels ≤ 70% observed only for two CF isolates (Figure 5A). This evidence concerns the gene LIAS and cystic fibrosis.