FIG 4.

Coinfection with mucoid P. aeruginosa confers an increase in S. maltophilia persistence. BALB/cJ mice were intratracheally infected with ∼10⁷ CFU of S. maltophilia K279a and P. aeruginosa mPA0831 alone and in combination, and groups were euthanized at 24, 48, or 72 h postinfection. Bacterial load in lung homogenate (A) and in BALF (B) were enumerated via viable colony counting on differential medium. Mean ± SEM, n = 4 to 12. Two-way ANOVA with Tukey’s post hoc comparisons, *, P < 0.05; **, P < 0.01; ***, P < 0.001. Significant outliers were identified via ROUT method and removed. The correlation between bacterial burdens of S. maltophilia K279a and P. aeruginosa mPA0831 in the lung (C) and BALF (D) were calculated. n = 19 to 22. Linear regression with automatic outlier elimination and two-tailed Spearman correlation were performed on log-transformed bacterial counts. (E) Dual infections were also performed with S. maltophilia msm2 and P. aeruginosa mPA0831. Mean ± SEM, n = 8 to 10. Kruskal-Wallis test with Dunn’s post hoc comparisons. Significant outliers were identified via ROUT method and removed. (F) Calculations of the correlation between bacterial burdens of S. maltophilia msm2 and P. aeruginosa mPA0831 in the lung were also performed. n = 10. Linear regression with automatic outlier elimination and two-tailed Spearman correlation were performed on log-transformed bacterial counts. Groups with undetectable colony counts were represented at the limit of detection.