The inflammasome pathway is activated by dengue virus non-structural protein 1 and is protective during dengue virus infection.

Dengue virus (DENV) is a medically important flavivirus causing an estimated 50-100 million dengue cases annually, some of whom progress to severe disease. DENV non-structural protein 1 (NS1) is secreted from infected cells and has been implicated as a major driver of dengue pathogenesis by inducing endothelial barrier dysfunction. However, less is known about how DENV NS1 interacts with immune cells and what role these interactions play. Here we report that DENV NS1 can trigger activation of inflammasomes, a family of cytosolic innate immune sensors that respond to infectious and noxious stimuli, in mouse and human macrophages. DENV NS1 induces the release of IL-1ß in a caspase-1 dependent manner. Additionally, we find that DENV NS1-induced inflammasome activation is independent of the NLRP3, Pyrin, and AIM2 inflammasome pathways, but requires CD14. Intriguingly, DENV NS1-induced inflammasome activation does not induce pyroptosis and rapid cell death; instead, macrophages maintain cellular viability while releasing IL-1ß. Lastly, we show that caspase-1/11-deficient, but not NLRP3-deficient, mice are more susceptible to lethal DENV infection. Together, these results indicate that the inflammasome pathway acts as a sensor of DENV NS1 and plays a protective role during infection.

The Inflammasome Pathway is Activated by Dengue Virus Non-structural Protein 1 and is Protective During Dengue Virus Infection.

Dengue virus (DENV) is a medically important flavivirus causing an estimated 50-100 million dengue cases annually, some of whom progress to severe disease. DENV non-structural protein 1 (NS1) is secreted from infected cells and has been implicated as a major driver of dengue pathogenesis by inducing endothelial barrier dysfunction. However, less is known about how DENV NS1 interacts with immune cells and what role these interactions play. Here we report that DENV NS1 can trigger activation of inflammasomes, a family of cytosolic innate immune sensors that respond to infectious and noxious stimuli, in mouse and human macrophages. DENV NS1 induces the release of IL-1ß in a caspase-1 dependent manner. Additionally, we find that DENV NS1-induced inflammasome activation is independent of the NLRP3, Pyrin, and AIM2 inflammasome pathways, but requires CD14. Intriguingly, DENV NS1-induced inflammasome activation does not induce pyroptosis and rapid cell death; instead, macrophages maintain cellular viability while releasing IL-1ß. Lastly, we show that caspase-1/11-deficient, but not NLRP3-deficient, mice are more susceptible to lethal DENV infection. Together, these results indicate that the inflammasome pathway acts as a sensor of DENV NS1 and plays a protective role during infection.

Urine testing is associated with inappropriate antibiotic use and increased length of stay in emergency department patients.

Background: Exposing patients with a low probability of disease to diagnostic testing with poor test characteristics leads to false positive results. Providers often act on these false results, which can cause unnecessary evaluation and treatment. The treatment of asymptomatic bacteriuria is discouraged, but it still frequently occurs in the inpatient setting; it is less studied in the Emergency Department (ED). In this study, we examine associations between urine testing, inappropriate antibiotic use, and length of stay in discharged ED patients at risk of urinary tract infection (UTI) misdiagnosis. Methods: A cohort of discharged ED patients at risk of UTI misdiagnosis was created by pulling visit information for patients presenting with abdominal pain, chest pain, headache, vaginal bleeding in pregnancy, and elderly females with weakness or confusion. Predictors of urine testing, and urinary tract infection treatment were determined with logistic regression analysis. A chart review of a representative sample of this cohort was then completed screening for the presence of urinary tract symptoms and urine culture results. Linear regression analysis was then used to generate an adjusted mean difference in length of stay between patients who had urine testing compared to those who did not. Results: About a quarter of chest pain and headache patients had urine testing, while approximately 75% of abdominal pain patients, vaginal bleeding in pregnancy, and elderly females with weakness or confusion did. Except for chest pain patients, the UTI treatment rate was more than double the positive culture rate, indicating overtreatment. A diagnosis of UTI is based on a combination of UTI symptoms and positive urine cultures, yet only about 15% of patients treated for UTI met these criteria. Lastly, in all chief complaint groups, the length of stay was significantly longer-30 min or more-for those who had urine testing compared to matched controls. Conclusions: In this observational study of patients at risk of UTI misdiagnosis, urine testing was associated with inappropriate antibiotic use and delayed discharge. There is pressure on providers to perform diagnostic testing, but in patients without specific UTI symptoms, urine testing might cause more harm than benefit.

Preventing COVID-19 Transmission in Education Settings.

OBJECTIVES: In fall 2020, community hubs opened in San Francisco, California, to support vulnerable groups of students in remote learning. Our objectives were to (1) describe adherence to coronavirus disease 2019 (COVID-19) mitigation policies in these urban, low-income educational settings; (2) assess associations between policy adherence and in-hub COVID-19 transmission; and (3) identify barriers to and facilitators of adherence. METHODS: We conducted a mixed-methods study from November 2020 to February 2021. We obtained COVID-19 case data from the San Francisco Department of Public Health, conducted field observations to observe adherence to COVID-19 mitigation policies, and surveyed hub leaders about barriers to and facilitators of adherence. We summarized quantitative data using descriptive statistics and qualitative data using thematic content analysis. RESULTS: A total of 1738 children were enrolled in 85 hubs (39% Hispanic, 29% Black). We observed 54 hubs (n = 1175 observations of children and 295 observations of adults). There was high community-based COVID-19 incidence (2.9-41.2 cases per 100 000 residents per day), with 36 cases in hubs and only 1 case of hub-based transmission (adult to adult). Sixty-seven percent of children and 99% of adults were masked. Fifty-five percent of children and 48% of adults were distanced ≥6 ft. Facilitators of mitigation policies included the following: for masking, reminders, adequate supplies, and "unmasking zones"; for distancing, reminders and distanced seating. CONCLUSIONS: We directly observed COVID-19 mitigation in educational settings, and we found variable adherence. However, with promotion of multiple policies, there was minimal COVID-19 transmission (despite high community incidence). We detail potential strategies for increasing adherence to COVID-19 mitigation.