Figure 6. Repeated serum treatment selects for serum resistance, increased vacJ expression, and increased outer membrane stability.

(A) Serum sensitive clinical isolate H725 was treated three times in 2.5% NHS and survival quantified after the passage indicated. (B) Following each passage in the bactericidal assay survivors were tested for relative expression of vacJ mRNA by qRT-PCR and (C) survival in the presence of 25 mM EDTA. Values represent two independent experiments in triplicate ± SD.^* P<0.05, ^*** P<0.001.