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Browsing by Author "Chen, Jenn-Wei"

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    Comparative nutritional and chemical phenome of Clostridium difficile isolates determined using phenotype microarrays
    Scaria, Joy; Chen, Jenn-Wei; Useh, Nicodemus; He, Hongxuan; McDonough, Sean P.; Mao, Chunhong; Sobral, Bruno; Chang, Yung-Fu (International Society for Infectious Diseases, 2014-10)
    Objectives: Clostridium difficile infection (CDI) is the leading cause of infectious diarrhea in North America and Europe. The risk of CDI increases significantly in the case where antimicrobial treatment reduces the number of competing bacteria in the gut, thus leading to the increased availability of nutrients and loss of colonization resistance. The objective of this study was to determine comprehensive nutritional utilization and the chemical sensitivity profile of historic and newer C. difficile isolates and to examine the possible role of the phenotype diversity in C. difficile virulence. Methods: Phenotype microarrays (PMs) were used to elucidate the complete nutritional and chemical sensitivity profile of six C. difficile isolates. Results: Of the 760 nutrient sources tested, 285 compounds were utilized by at least one strain. Among the C. difficile isolates compared, R20291, a recent hypervirulent outbreak-associated strain, appears to have an expanded nutrient utilization profile when compared to all other strains. Conclusions: The expanded nutritional utilization profile of some newer C. difficile strains could be one of the reasons for infections in patients who are not exposed to the hospital environment or not undergoing antibiotic treatment. This nutritional profile could be used to design tube feeding formulas that reduce the risk of CDI.
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    Differential Stress Transcriptome Landscape of Historic and Recently Emerged Hypervirulent Strains of Clostridium difficile Strains Determined Using RNA-seq
    Scaria, Joy; Mao, Chunhong; Chen, Jenn-Wei; McDonough, Sean P.; Sobral, Bruno; Chang, Yung-Fu (Public Library of Science, 2014-11-07)
    C. difficile is the most common cause of nosocomial diarrhea in North America and Europe. Genomes of individual strains of C. difficile are highly divergent. To determine how divergent strains respond to environmental changes, the transcriptomes of two historic and two recently isolated hypervirulent strains were analyzed following nutrient shift and osmotic shock. Illumina based RNA-seq was used to sequence these transcriptomes. Our results reveal that although C. difficile strains contain a large number of shared and strain specific genes, the majority of the differentially expressed genes were core genes. We also detected a number of transcriptionally active regions that were not part of the primary genome annotation. Some of these are likely to be small regulatory RNAs.