Project description:Clostridium difficile is an important nosocomial pathogen and the leading cause of hospital-acquired diarrhea. Antibiotic use is the primary risk factor for the development of C. difficile-associated disease because it disrupts normal protective gut flora and enables C. difficile to colonize the colon. C. difficile damages host tissue by secreting toxins and disseminates by forming spores. The toxin-encoding genes, tcdA and tcdB are part of a pathogenicity locus, which also encodes the gene tcdR that codes for the toxin genes positive regulator. TcdR is an alternate sigma factor that initiates transcription of tcdA and tcdB at their promoters. Alternative sigma factors are known to regulate virulence and virulence associated genes in many pathogenic bacteria. We created a tcdR mutant in the epidemic-type C. difficile R20291 strain in an attempt to identify the global role of tcdR. A site-directed mutation in tcdR affected both toxin production and sporulation in C. difficile R20291. Spores derived from the tcdR mutant were found to be mildly temperature sensitive. Moreover, nearly two fold more taurocholate was needed to germinate spores from the tcdR mutant than the spores prepared from the wild-type parent strain. Comparison of the tcdR mutant transcriptome with the parent strain revealed many differentially expressed late sporulation genes in the tcdR mutant. These data suggests that gene regulatory networks of toxin production and sporulation in Clostridium difficile are linked with each other.
Project description:Clostridium difficile (C. difficile) strains belonging to PCR ribotype 027, PFGE type NAP1, REA type B1 and toxinotype III, termed NAP1/027, have been implicated in the increased frequency of outbreaks of Clostridium difficile-associated diarrhoea (CDAD) in North America and Europe. The NAP1/027 strains appears to be more virulent with an increased mortality and frequency of relapse. Current European C. difficile microarrays are designed to the first sequenced and annotated C. difficile complete genome - strain 630 (ribotype 12). A high density oligonucleotide microarray was designed to C. difficile 630 (CD630) sequence and extra probes corresponding to two PCR ribotypes O27 strains C. difficile R20291 and QCD-32g58 were also included. Comparative genomic hybridisation was used to identify markers of ribotype 027 strains and markers to identify CD630. Strains hybridised to the array included the most prevalent ribotypes found in the UK and Europe (106 and 001) as well as the emerging hypervirulent ribotype 078.
Project description:The experiment intends to reveal the difference in gene expression profiles between the wild-type strain and the ∆cwp66 mutant of Clostridioides difficile. We first constructed the ∆cwp66 mutant, and the phenotypic changes of the ∆cwp66 mutant against the wild-type strain were studied. To further elucidate the mechanism of phenotypic changes of the ∆cwp66 mutant, RNA-sequencing experiments were carried out to reveal the underlying mechanism of phenotypic changes.
Project description:Clostridioides difficile is one of the most common nosocomial pathogens and a global public health threat. Upon colonization of the gastrointestinal tract, C. difficile is exposed to a rapidly changing polymicrobial environment and a dynamic metabolic milieu. Despite the link between the gut microbiota and susceptibility to C. difficile, the impact of synergistic interactions between the microbiota and pathogens on the outcome of infection is largely unknown. Here, we show that microbial cooperation between C. difficile and Enterococcus has a profound impact on the growth, metabolism, and pathogenesis of C. difficile.. Through a process of nutrient restriction and metabolite cross-feeding, E. faecalis shapes the metabolic environment in the gut to enhance C. difficile fitness and increase toxin production. These findings demonstrate that members of the microbiota, such as Enterococcus, have a previously unappreciated impact on C. difficile behavior and virulence.
Project description:The intestines house a diverse microbiota that must compete for nutrients to survive, but the specific limiting nutrients that control pathogen colonization are not clearly defined. Clostridioides difficile colonization typically requires prior disruption of the microbiota, suggesting that outcompeting commensals for resources is key in establishing C. difficile infection (CDI). The immune protein calprotectin (CP) is released into the gut lumen during CDI to chelate zinc (Zn) and other essential nutrient metals. Yet, the impact of Zn limitation on C. difficile colonization is unknown. To define C. difficile responses to Zn limitation, we performed RNA sequencing on C. difficile exposed to CP. In media with CP, C. difficile upregulated genes involved in metal homeostasis and amino acid metabolism.
Project description:Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.
Project description:Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.investigated by determining changes in transcript profiles when aerobic steady-state cultures were depleted of air.
Project description:We conducted whole genome sequencing on eight evolved E. coli strains (S1–S8) and the parental wild-type (WT) strain to identify mutations arising from ofloxacin treatments. These strains (S1-S8), generated through fluoroquinolone-mediated adaptive laboratory evolution (ALE), exhibited varying levels of tolerance and resistance. The ALE experiment involved intermittent antibiotic treatments of eight independent cultures over 22 days. The untreated WT strain served as a baseline to pinpoint mutations in the evolved strains.
Project description:Gene expression level of Clostridioides difficile (C. difficile) strain R20291 comparing control C. difficile carring pMTL84151 as vector plasmid with C. difficile conjugated with a pMTL84151-03890 gene. Goal was to determine the effects of 03890 gene conjugation on C. difficile strain R20291 gene expression.