The chaperone ClpC participates in sporulation, motility, biofilm, and toxin production of Clostridioides difficile.

OBJECTIVES: Clostridioides difficile is a nosocomial pathogen that is associated with the use of antibiotics. One of the most worrying aspects of C. difficile infection is its ability to resist antimicrobial therapies, owing to spore formation. In several bacterial pathogens, proteases of the Clp family participate in phenotypes associated with persistence and virulence. This suggests that these proteins could be involved in virulence-related traits. In this study, we analysed the role of ClpC chaperone-protease of C. difficile in virulence-related traits by comparing the phenotypes of wild-type and mutant strains lacking the clpC gene (ΔclpC). METHODS: We performed biofilm, motility, spore formation, and cytotoxicity assays. RESULTS: Our results show significant differences between the wild-type and ΔclpC strains in all analysed parameters. CONCLUSIONS: Based on these findings, we conclude that clpC plays a role in the virulence properties of C. difficile.

CdsH Contributes to the Replication of Salmonella Typhimurium inside Epithelial Cells in a Cysteine-Supplemented Medium.

Salmonella Typhimurium is a facultative, intracellular pathogen whose products range from self-limited gastroenteritis to systemic diseases. Food ingestion increases biomolecules' concentration in the intestinal lumen, including amino acids such as cysteine, which is toxic in a concentration-dependent manner. When cysteine's intracellular concentration reaches toxic levels, S. Typhimurium expresses a cysteine-inducible enzyme (CdsH), which converts cysteine into pyruvate, sulfide, and ammonia. Despite this evidence, the biological context of cdsH's role is not completely clear, especially in the infective cycle. Since inside epithelial cells both cdsH and its positive regulator, ybaO, are overexpressed, we hypothesized a possible role of cdsH in the intestinal phase of the infection. To test this hypothesis, we used an in vitro model of HT-29 cell infection, adding extra cysteine to the culture medium during the infective process. We observed that, at 6 h post-invasion, the wild type S. Typhimurium proliferated 30% more than the ΔcdsH strain in the presence of extra cysteine. This result shows that cdsH contributes to the bacterial replication in the intracellular environment in increased concentrations of extracellular cysteine, strongly suggesting that cdsH participates by increasing the bacterial fitness in the intestinal phase of the S. Typhimurium infection.

Effect of antibiotic to induce Clostridioides difficile-susceptibility and infectious strain in a mouse model of Clostridioides difficile infection and recurrence.

The anaerobic bacterium Clostridioides difficile is the leading cause of antibiotic-associated diarrhea that can culminate in life-threating colitis. During the C. difficile infection (CDI), C. difficile produces toxins that generate the clinical symptoms of the disease, and produce spores, which persist in the host during antibiotic treatment and can cause recurrent CDI (R-CDI). In this work, we aimed to compare three antibiotic regimens in the susceptibility of mice to CDI and R-CDI (i.e., antibiotic cocktail followed by clindamycin, 5 days of cefoperazone and 10 days of cefoperazone) with three different C. difficile isolates (i.e., strains 630; R20291, and VPI 10463). We observed that the severity of the clinical symptoms of CDI and R-CDI was dependent on the antibiotic treatment used to induce C. difficile-susceptibility, and that the three strains generated a different onset to diarrhea and weight loss in mice that were administrated with the same antibiotic treatment and which differed in comparison to the effect previously reported by other research groups. Our results suggest that, in our experimental conditions, in those animals treated with antibiotic cocktail followed by clindamycin, infection with strain R20291 had the highest diarrhea manifestation in comparison to strains 630 and VPI 10463. In animals treated with cefoperazone for 5 days, infection with strains R20291 or 630 had the highest diarrhea manifestation in comparison to VPI 10463, while in animals treated with cefoperazone for 10 days, infection with strain R20291 or VPI 10463, but not 630, had the highest diarrhea manifestation.

Genome Sequence of Clostridium paraputrificum 373-A1 Isolated in Chile from a Patient Infected with Clostridium difficile.

Clostridium paraputrificum is a gut microbiota member reported in several cases of bacteremia and coinfections. So far, only one genome sequence of a C. paraputrificum (AGR2156) isolate is available. Here, we present the draft genome of C. paraputrificum strain 373-A1, isolated from stools from a patient with C. difficile infection.