Resveratrol (3,4',5-trihydroxystilbene) is a polyphenolic stilbene found in the skins of red fruits, including grapes, that may be responsible for some of the health benefits ascribed to consumption of red wine. Resveratrol has been shown to have antioxidant properties and can act as an estrogen agonist. This study examined the anti-inflammatory effects of resveratrol on human airway epithelial cells. Resveratrol and the related molecule quercetin, but not deoxyrhapontin, inhibited IL-8 and granulocyte-macrophage colony-stimulating factor release from A549 cells. Neither the estrogen receptor antagonist tamoxifen nor the glucocorticoid antagonist mifepristone altered the inhibitory effect of resveratrol. The mechanism of resveratrol action was investigated further using luciferase reporter genes stably transfected into A549 cells. Resveratrol and quercetin inhibited NF-kappaB-, activator protein-1-, and cAMP response element binding protein-dependent transcription to a greater extent than the glucocorticosteroid dexamethasone. These compounds also had no significant effect on acetylation or deacetylation of core histones. Resveratrol, but not estradiol or N-acetyl cysteine, inhibited cytokine-stimulated inducible nitric oxide synthase expression and nitrite production (IC50 = 3.6 +/- 2.9 microM) in human primary airway epithelial cells. Resveratrol also inhibited granulocyte-macrophage colony-stimulating factor release (IC50 = 0.44 +/- 0.17 microM), IL-8 release (IC50 = 4.7 +/- 3.3 microM), and cyclooxygenase-2 expression in these cells. This study demonstrates that resveratrol and quercetin have novel nonsteroidal anti-inflammatory activity that may have applications for the treatment of inflammatory diseases.

The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the assembly of the T6SS sheath structure, the contraction of which propels a payload of effector proteins into neighboring cells. Despite their key function, TssA proteins exhibit unexpected diversity and exist in two major forms, a short form (TssAS) and a long form (TssAL). While TssAL proteins interact with a partner, called TagA, to anchor the distal end of the extended sheath, the mechanism for the stabilization of TssAS-containing T6SSs remains unknown. Here we discover a class of structural components that interact with short TssA proteins and contribute to T6SS assembly by stabilizing the polymerizing sheath from the baseplate. We demonstrate that the presence of these components is important for full sheath extension and optimal firing. Moreover, we show that the pairing of each form of TssA with a different class of sheath stabilization proteins results in T6SS apparatuses that either reside in the cell for some time or fire immediately after sheath extension. We propose that this diversity in firing dynamics could contribute to the specialization of the T6SS to suit bacterial lifestyles in diverse environmental niches.

Antimicrobial resistance in enteric or urinary Escherichia coli is a risk factor for invasive E. coli infections. Due to widespread trimethoprim resistance amongst urinary E. coli and increased bacteraemia incidence, a national recommendation to prescribe nitrofurantoin for uncomplicated urinary tract infection was made in 2014. Nitrofurantoin resistance is reported in <6% urinary E. coli isolates in the UK, however, mechanisms underpinning nitrofurantoin resistance in these isolates remain unknown. This study aimed to identify the genetic basis of nitrofurantoin resistance in urinary E. coli isolates collected from north west London and then elucidate resistance-associated genetic alterations in available UK E. coli genomes. As a result, an algorithm was developed to predict nitrofurantoin susceptibility. Deleterious mutations and gene-inactivating insertion sequences in chromosomal nitroreductase genes nfsA and/or nfsB were identified in genomes of nine confirmed nitrofurantoin-resistant urinary E. coli isolates and additional 11 E. coli isolates that were highlighted by the prediction algorithm and subsequently validated to be nitrofurantoin-resistant. Eight categories of allelic changes in nfsA, nfsB, and the associated gene ribE were detected in 12412 E. coli genomes from the UK. Evolutionary analysis of these three genes revealed homoplasic mutations and explained the previously reported order of stepwise mutations. The mobile gene complex oqxAB, which is associated with reduced nitrofurantoin susceptibility, was identified in only one of the 12412 genomes. In conclusion, mutations and insertion sequences in nfsA and nfsB were leading causes of nitrofurantoin resistance in UK E. coli . As nitrofurantoin exposure increases in human populations, the prevalence of nitrofurantoin resistance in carriage E. coli isolates and those from urinary and bloodstream infections should be monitored.

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Background: Despite recommendations regarding prompt treatment of cases and enhanced hygiene measures, scarlet fever outbreaks increased in England between 2014-2018. Methods: We undertook a prospective, intensive contact tracing study in schools with consecutive scarlet fever cases to assess the impact of standard interventions on transmission of Streptococcus pyogenes between cases, classroom contacts, households, and classroom environments over 4 weeks using genome sequencing. Findings: Six classes, comprising 12 scarlet fever cases, 17 household contacts, and 278 classroom contacts were recruited. Prevalence of the outbreak strain in asymptomatic classroom contacts was high, increasing from 9.6% in week 1, to 26.9% in week 2, 23.9% in week 3, then 14.3% in week 4. Colonisation with non-outbreak strains was 0 - 7.5%. Genome sequencing showed clonality of isolates within each of six classes, confirming recent transmission accounted for high carriage. Of asymptomatic classroom contacts with S. pyogenes-positive throat swabs who were tested for transmissibility, 6/28 (21%) had positive cough plates and/or hand swabs, of whom three remained S. pyogenes-positive for 3 weeks. Only 1/60 surface swabs taken in 3 classrooms yielded S. pyogenes. In contrast, settle plates placed in elevated locations were S. pyogenes-positive in both classrooms tested. Interpretation: S. pyogenes transmission in schools is intense and may occur prior to, or in spite of reported treatment of cases, underlining a need for rapid case management. Despite guideline adherence, heavy shedding of S. pyogenes by small numbers of classroom contacts may perpetuate outbreaks, and airborne transmission has a plausible role in spread.

20 21 2 These authors have contributed equally to this work. 22 23 24 KEYWORDS 25 26 Type VI secretion system, interbacterial competition, contact-dependent killing, toxin 27 delivery, TssA, TagB, TagA, sheath stabilization, sheath contraction, Pseudomonas. 28 29 30 ABSTRACT 31 32The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily 33 involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the 34 assembly of the T6SS sheath structure, the contraction of which propels a payload of effector 35proteins into neighboring cells. Despite their key function, TssA proteins exhibit unexpected 36 diversity and exist in two major forms, a short (TssAS) and a long (TssAL) TssA. Whilst 37TssAL proteins interact with a partner, called TagA, to anchor the distal end of the extended 38sheath, the mechanism for the stabilization of TssAS-containing T6SSs remains unknown. 39Here we discover a novel class of structural components that interact with short TssA 40proteins and contribute to T6SS assembly by stabilizing the polymerizing sheath from the 41 baseplate. We demonstrate that the presence of these components is important for full sheath 42 extension and optimal firing. Moreover, we show that the pairing of each form of TssA with 43 a different class of sheath stabilization proteins results in T6SS apparatuses that either reside 44in the cell for a while or fire immediately after sheath extension, thus giving rise to different 45 aggression behaviors. We propose that this functional diversity could contribute to the 46 specialization of the T6SS to suit bacterial lifestyles in diverse environmental niches. 47 48 49Bacteria live in complex polymicrobial communities that are shaped by interspecies 50 cooperation and competition. As resources are limited, antagonistic strategies are a major 51 driver of survival and success for bacterial populations. One of the most elaborate bacterial 52weapons is the type VI secretion system (T6SS), which not only promotes inter-bacterial and 53inter-kingdom competition (1-3), but is also involved in the interaction of bacteria with their 54

Background Antimicrobial resistance in enteric or urinary E. coli might predispose invasive E. coli infection and bacteraemia. Nitrofurantoin resistance occurs in <6% of UK urinary E. coli isolates, however, 2018 national recommendations to prescribe nitrofurantoin for uncomplicated urinary tract infection (UTI) raised concerns for increased prevalence of nitrofurantoin-resistant E. coliin the future. Therefore, we investigated mechanisms of nitrofurantoin resistance in UK E. coli isolates and assessed their occurrences in a large dataset of E. coli genomes. Methods To elucidate chromosomal and acquired genetic determinants of nitrofurantoin resistance in E. coli, we analysed whole-genome sequences of nine randomly selected nitrofurantoin-resistant UTI E. coli isolates from West London. We then performed targeted analysis of 12,412 E. coli genomes collected from across the UK and predicted nitrofurantoin susceptibility from identified genotypes. Results Using comparative genomics, we found known and novel point mutations or insertion sequences (ISs) in chromosomal genes encoding oxygen-insensitive nitroreductases NfsA and NfsB in the nine isolates. Most of these genetic alterations resulted in gene inactivation. We also identified the same kinds of mutations in NfsA, NfsB, and their associated enzyme RibE in a number of 12,412 E. coli genomes. We also observed homoplasic mutations in all these proteins. By contrast, multidrug efflux pump OqxAB, which confers resistance when horizontally transferred, was only encoded by one genome. Conclusions Chromosomal de novo mutations and ISs are main causes of nitrofurantoin resistance in UK E. coli. Prevalence of nitrofurantoin resistance should be monitored among urine, blood, and enteric isolates as nitrofurantoin exposure increases.