In vivo synthesis of bacterial amyloid curli contributes to joint inflammation during S. Typhimurium infection.

Reactive arthritis, an autoimmune disorder, occurs following gastrointestinal infection with invasive enteric pathogens, such as Salmonella enterica. Curli, an extracellular, bacterial amyloid with cross beta-sheet structure can trigger inflammatory responses by stimulating pattern recognition receptors. Here we show that S. Typhimurium produces curli amyloids in the cecum and colon of mice after natural oral infection, in both acute and chronic infection models. Production of curli was associated with an increase in anti-dsDNA autoantibodies and joint inflammation in infected mice. The negative impacts on the host appeared to be dependent on invasive systemic exposure of curli to immune cells. We hypothesize that in vivo synthesis of curli contributes to known complications of enteric infections and suggest that cross-seeding interactions can occur between pathogen-produced amyloids and amyloidogenic proteins of the host.

Parallel evolution leading to impaired biofilm formation in invasive Salmonella strains.

Pathogenic Salmonella strains that cause gastroenteritis are able to colonize and replicate within the intestines of multiple host species. In general, these strains have retained an ability to form the rdar morphotype, a resistant biofilm physiology hypothesized to be important for Salmonella transmission. In contrast, Salmonella strains that are host-adapted or even host-restricted like Salmonella enterica serovar Typhi, tend to cause systemic infections and have lost the ability to form the rdar morphotype. Here, we investigated the rdar morphotype and CsgD-regulated biofilm formation in two non-typhoidal Salmonella (NTS) strains that caused invasive disease in Malawian children, S. Typhimurium D23580 and S. Enteritidis D7795, and compared them to a panel of NTS strains associated with gastroenteritis, as well as S. Typhi strains. Sequence comparisons combined with luciferase reporter technology identified key SNPs in the promoter region of csgD that either shut off biofilm formation completely (D7795) or reduced transcription of this key biofilm regulator (D23580). Phylogenetic analysis showed that these SNPs are conserved throughout the African clades of invasive isolates, dating as far back as 80 years ago. S. Typhi isolates were negative for the rdar morphotype due to truncation of eight amino acids from the C-terminus of CsgD. We present new evidence in support of parallel evolution between lineages of nontyphoidal Salmonella associated with invasive disease in Africa and the archetypal host-restricted invasive serovar; S. Typhi. We hypothesize that the African invasive isolates are becoming human-adapted and 'niche specialized' with less reliance on environmental survival, as compared to gastroenteritis-causing isolates.

Evaluation of an Online Home Caregiver Support Program for Non-Professional Caregivers of Patients With Palliative Care Needs.

BACKGROUND: Caring for loved ones with palliative needs can be very stressful for carers'. To address this growing issue, an online Home Caregiver Support Program course was created to provide information to non-professional home caregivers about end-of-life care. OBJECTIVES: To measure non-professional caregivers' perceived level of competence in addressing physical, psychological, social, and spiritual needs before and after completing online training modules. METHODS: Learners rated their competence before and after completing online modules addressing 4 key dimensions relevant to palliative caregivers. Self-ratings of competence were assessed through surveys, completed before and after the online modules. Scores from before and after each module were compared to determine if the online course had increased participant competence. The Wilcoxon signed rank test was used to analyze participant responses to the pre- and post-survey questions. RESULTS: A total of 176 participants who completed one or more of the online modules between July 2017-December 2018, 70 (40%) of the participants completed at least one pre- and post-module survey and did not declare themselves as a professional caregiver. Participating in the online Home Caregiver Support Program increased participants' ratings of perceived competence in all domains (p < .01). This significance was maintained when professional caregivers were added to our analysis. CONCLUSION: After the completing the modules, participants' self-ratings of perceived competence increased suggesting that participants completing the online program had improved knowledge in addressing the physical, psychological, social, and spiritual challenges faced by non-professional caregivers.

Changing Results to Change Results: Nudging Antimicrobial Prescribing for Clostridium difficile.

BACKGROUND: Patients who test positive for Clostridium difficile by polymerase chain reaction (PCR), with a negative toxin enzyme immunoassay (EIA), are commonly colonized and do not require treatment. However, clinicians often treat based on a positive PCR result regardless of the toxin EIA result. We evaluated the clinical impact of a microbiology reporting nudge, changing from a report that included both assay results along with treatment recommendations to one that suggested clinicians consider C difficile colonization or early infection. METHODS: We conducted a retrospective cohort study of all adult patients admitted to a large multisite community hospital with a positive C difficile PCR result and negative toxin EIA from January 1, 2016 to June 30, 2018. We examined total days of therapy (DOT) and impacts on clinical outcomes. RESULTS: One hundred ninety-nine episodes occurred preintervention and 165 episodes occurred postintervention. The mean DOTs per episode decreased from 13.6 to 7.9 days (difference -5.8 days; 95% confidence interval, -3.9 to -7.6) postintervention, with statistical process control charts suggesting special cause variation. Patients receiving no treatment increased from 6.5% to 23.6% postintervention (P < .0001). No significant changes in subsequent toxin positive disease (9.0% vs 6.7%), colectomy (0% vs 0.6%), mortality (7.5% vs 12.1%), or length of stay (18.5 vs 16 days) were observed. CONCLUSIONS: Microbiology reporting nudges raising the possibility of C difficile colonization were associated with altered prescribing, reinforcing a postanalytic strategy for invoking change. Decreases in antimicrobial prescribing occurred without increasing subsequent disease or other adverse outcomes, suggesting a safe strategy for decreasing unnecessary treatment of C difficile colonization.

Metabolic Activation of CsgD in the Regulation of Salmonella Biofilms.

Among human food-borne pathogens, gastroenteritis-causing Salmonella strains have the most real-world impact. Like all pathogens, their success relies on efficient transmission. Biofilm formation, a specialized physiology characterized by multicellular aggregation and persistence, is proposed to play an important role in the Salmonella transmission cycle. In this manuscript, we used luciferase reporters to examine the expression of csgD, which encodes the master biofilm regulator. We observed that the CsgD-regulated biofilm system responds differently to regulatory inputs once it is activated. Notably, the CsgD system became unresponsive to repression by Cpx and H-NS in high osmolarity conditions and less responsive to the addition of amino acids. Temperature-mediated regulation of csgD on agar was altered by intracellular levels of RpoS and cyclic-di-GMP. In contrast, the addition of glucose repressed CsgD biofilms seemingly independent of other signals. Understanding the fine-tuned regulation of csgD can help us to piece together how regulation occurs in natural environments, knowing that all Salmonella strains face strong selection pressures both within and outside their hosts. Ultimately, we can use this information to better control Salmonella and develop strategies to break the transmission cycle.