Fig 4.

Diagnostic RT-LAMP assay for P. aeruginosa using transgenic E. coli as an internal assay control. Time to threshold (Tt) values are shown for multiplex RT-LAMP reactions incorporating diagnostic primer sets for P. aeruginosa and RNA-specific primers for the transgenic expression vector pKTM_IAC to serve as an internal assay control. Results are shown for control reactions lacking the clinical specimen matrix and for a series of three separate stool specimens. All specimens were tested in the presence of E. coli carrying pKTM_IAC, (A) without or (B) with the introduction of exogenous P. aeruginosa. Dilutions of stool specimens are indicated. Results from three technical replicates for each specimen are superimposed, with Tt values significantly (P ≤ 0.05, two-tailed T test) higher than those of controls lacking clinical matrices indicated with an asterisk (*). Gray horizontal bars express the mean for replicates.