A. Weight monitoring during S. maltophilia lung infection. Results are expressed as percentage of weight loss with respect to control mice (100%). The horizontal line shows a 10% weight loss with regard to mean body weight of control mice. Differences in weight reduction were all significant (p < 0.01, Fisher's exact test) compared to control mice, except for Sm111 exposed mice at day 1 post-exposure (p.e.). B. S. maltophilia survival in mouse lungs 3 days p.e.. For each exposure, four mice each were included for determination of bacterial deposition to the lungs at 1 h and 3 days p.e.. Results are expressed as mean + SD. C. Cytokine levels measured on day 3 p.e. in lung homogenates. Results were normalized to the lung wet

weight (pg/mg) and expressed as box and whiskers: the box extends from the 25th percentile to 75th percentile, with a line at the median (50th percentile); the whiskers indicate the lowest and the highest value. * p < 0.05 or ** p < 0.01, OICR-9429 supplier Kruskal-Wallis test followed by Dunn’s multiple comparison post-test. Lung clearance results of S. maltophilia infection are summarized in Figure 5B. The initial deposition of S. maltophilia in the mouse lung was assessed by viable count 1 h p.e.. All S. maltophilia strains were almost completely eradicated from mouse lung (> 99%), while Sm111 CF and Sm46 non-CF blood isolates were eradicated less effectively (0.51 and 0.71%

retention, HTS assay respectively) than non-CF respiratory strains (0.04% retention), although

these differences were not statistically significant. No correlation was found between in vitro biofilm formation and in vivo lung selleck chemicals colonization. Pulmonary levels of cytokines detected on day 3 p.e. are shown in Figure 5C. Higher levels of Dimethyl sulfoxide TNF-α were significantly observed in the lungs of mice infected by Sm111 CF strain, compared to control mice (median: 1.63 vs 0.050 pg/mg, respectively; p < 0.01). Moreover, higher levels of KC were observed on day 3 p.e. in the lungs of mice infected by invasive Sm46 strain, compared to control mice (median: 23.28 vs 0.42 pg/mg, respectively; p < 0.01). Different genotypes are associated to strong biofilm formation in CF and non-CF isolates PCR-based typing of 89 (84 clinical, 5 ENV) S. maltophilia strains for spgM, rmlA, and rpfF genes showed an overall prevalence of 88.8, 65.2, and 61.8%, respectively. The presence of rmlA, spgM or rpfF did not significantly affect the mean amount of biofilm formed by CF or non-CF isolates. However, considering the strain population as a whole, the presence of rmlA significantly improved biofilm formation (0.820 ± 0.785 vs 0.415 ± 0.278, rmlA + vs rmlA -, respectively; p = 0.01). With regard to biofilm categories, in CF strains displaying strong and moderate biofilm-producer phenotype the frequencies of spgM + and rpfF + isolates were significantly (p < 0.01) higher than rmlA + ones (strong biofilm producer: 92.3 vs 84.6 vs 61.5%, respectively; moderate biofilm producers: 90 vs 60 vs 20%, respectively).