Capsule inhibitors sensitize UPEC K1 strain to serum-mediated killing.

<p><i>E. coli</i> UTI89 and genetic capsule mutants were grown in the presence and absence of DU003 or DU011 at 50 µM and exposed to human serum. Bacterial metabolism and viability was measured using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide). UTI89 grown in the presence of 50 µM DU003 or DU011 were significantly more sensitive to pooled human serum compared to control UTI89 (** p = 0.0067). This was similar to the serum sensitivity of the capsule mutant UTI89 ΔRII. ΔRI and ΔRII indicate a complete deletion of Region I of the capsule <i>kps</i> and Region II capsule <i>neu</i> loci, respectively.