2%, respectively; p = 0.03) (Figure 2). Figure 2 Biofilm formed on polystyrene by 98 clinical and environmental S. maltophilia strains. Biofilm amount formed after 24 h incubation at 37°C was assessed by microtiter colorimetric assay. Strains from non-CF patients are represented by blue bars, strains from CF patients are represented by cyan bars, and strains from environmental sources (ENV) are represented by black bars. Each strain was tested in quadruplicate on two different occasions. Results were subtracted from negative

control (OD492 = 0.096) and expressed as means + SDs. Biofilm forming ability varied greatly among strains tested (OD492 range: 0.030-3.646), although values distribution was significantly less skewed among CF strains compared to non-CF and ENV strains (coefficient of variation: 70.0 vs 90.2, and 85.8%, respectively; p < 0.001). Veliparib ic50 Similarly, among ENV strains variability in biofilm levels formed at 25°C was significantly lower than that observed at 37°C (36. 8 vs 85.8%, respectively; p < 0.001). The mean biofilm formed by CF strains as a whole was significantly lower than that formed by non-CF strains (OD492, mean ± SD: 0.498 ± 0.348 vs 0.893 ± 0.806, respectively; p < 0.05) (Figure 3A), even after normalization

on mean generation time (biofilm/MGT: 0.14 ± 0.11 vs 0.31 ± 0.31; CF vs non -CF strains, respectively; p < 0.01) (Figure 3B). No difference in biofilm formation was observed between clinical and ENV isolates (Figure 3A). With regard to biofilm

categories, a significantly higher percentage of weak and strong biofilm Clomifene Anlotinib producers was found in non-CF strains compared to CF ones (weak: 10.6 vs 2.4%, respectively, p < 0.05; strong: 85.1 vs 63.4%, respectively, p < 0.0001) (Figure 3C). Contrarily, CF group exhibited a significantly higher proportion of moderate biofilm forming strains (23.0 vs 2.0%, respectively, p < 0.0001) (Figure 3C). No significant difference in biofilm levels formed by non-CF strains was found according to the isolation site, although among respiratory strains, non-CF strains produced significantly higher biofilm levels compared to CF ones (0.960 ± 0.919 vs 0.498 ± 0.348, respectively; p < 0.05) (Figure 3D). Figure 3 Biofilm formation on polystyrene, growth rate, and susceptibility to oxidative stress among 98 clinical and environmental S. maltophilia strains. A. Biofilm levels (mean + SD) formed by CF, non-CF, and ENV (ENV-37: 37°C-grown strains; ENV-25: 25°C-grown strains) isolates. B. Biofilm formation normalized on mean generation time (MGT) by CF, non-CF, ENV-37, and ENV-25 isolates. C. Percentage distribution of non-CF (blue bars) and CF (cyan bars) isolates belonging to no (OD492 ≤ 0.096; n = 5), weak (0.096 < OD492 ≤ 0.192; n = 6), moderate (0.192 < OD492 ≤ 0.384; n = 11), or strong (OD492 > 0.384; n = 66) biofilm producer group. D. Biofilm formation (mean + SD) observed in non-CF strains, stratified by the isolation site, and CF strains. E.