Project description:Examination of E. coli transcripts present in bacteria in urine samples from 8 patients attending a urology clinic with symptoms of cystitis, as compared to transcripts present in the same E. coli strains during mid-exponential growth in filter-sterilized human urine in vitro.
Project description:Examination of E. coli transcripts present in bacteria in urine samples from 8 patients attending a urology clinic with symptoms of cystitis, as compared to transcripts present in the same E. coli strains during mid-exponential growth in filter-sterilized human urine in vitro. A 48 array study using total RNA recovered from eight clinical E. coli isolates immediately following collection from women and following culture in pooled human urine ex vivo. Each array measures the expression of the 5,379 ORFs in the CFT073 genome, using an average of 14 60-mer probes per ORF. Arrays were performed in triplicate: biological replicates of the in vitro-cultured samples and technical replicates of the in vivo samples.
Project description:The enteric bacterium Proteus mirabilis is a common cause of complicated urinary tract infections. In the study, microrarrays were used to analyze P. mirabilis gene expression in vivo from experimentally infected mice. Urine was collected at 1, 3, and 7d postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across 9 microarrays, 471 genes were upregulated and 82 were downregulated in vivo compared to in vitro broth culture. Genes upregulated in vivo encoded MR/P fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism, and portions of the TCA cycle. Flagella were downregulated. Ammonia assimilation gene glnA (glutamine synthetase) was repressed in vivo while gdhA (glutamate dehydrogenase) was upregulated in vivo. Contrary to our expectations, ammonia availability due to urease activity in P. mirabilis did not drive this gene expression. A gdhA mutant was growth-deficient in minimal medium with citrate as the sole carbon source, and loss of gdhA resulted in a significant fitness defect in the mouse model of urinary tract infection. Unlike Escherichia coli, which represses gdhA and upregulates glnA in vivo and cannot utilize citrate, the data suggest that P. mirabilis uses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential of P. mirabilis in the urinary tract. Voided urine from female CBA/J mice infected with Proteus mirabilis was collected and pooled in RNA stabilizing reagent (RNAprotect). Urine was collected at 1, 3, and 7 d postinfection. RNA was isolated from urine and log-phase LB cultures, converted to cDNA, and labeled with CyDye. Three arrays were completed per time point (9 arrays total). Slides were scanned with a ScanArray Express microarray scanner (Perkin Elmer) at 10 μm resolution and quantified using ScanArray Express software. Resulting data were normalized by total intensity and median spot intensities were identified using MIDAS (v. 2.22) software.