Persistent Salmonella enterica serovar Typhi sub-populations within host interrogated by whole genome sequencing and metagenomics.

Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever and, in some cases, chronic carriage after resolution of acute disease. This study examined sequential isolates of S. Typhi from a single host with persistent asymptomatic infection. These isolates, along with another S. Typhi isolate recovered from a household contact with typhoid fever, were subjected to whole genome sequencing and analysis. In addition, direct sequencing of the bile fluid from the host with persistent infection was also performed. Comparative analysis of isolates revealed three sub-populations of S. Typhi with distinct genetic patterns. Metagenomic sequencing recognised only two of the three sub-populations within the bile fluid. The detection and investigation of insertion sequences IS10R and associated deletions complemented analysis of single nucleotide polymorphisms. These findings improve our understanding of within-host dynamics of S. Typhi in cases of persistent infection and inform epidemiological investigations of transmission events associated with chronic carriers.

The evolution and international spread of extensively drug resistant Shigella sonnei.

Shigella sonnei causes shigellosis, a severe gastrointestinal illness that is sexually transmissible among men who have sex with men (MSM). Multidrug resistance in S. sonnei is common including against World Health Organisation recommended treatment options, azithromycin, and ciprofloxacin. Recently, an MSM-associated outbreak of extended-spectrum ß-lactamase producing, extensively drug resistant S. sonnei was reported in the United Kingdom. Here, we aimed to identify the genetic basis, evolutionary history, and international dissemination of the outbreak strain. Our genomic epidemiological analyses of 3,304 isolates from the United Kingdom, Australia, Belgium, France, and the United States of America revealed an internationally connected outbreak with a most recent common ancestor in 2018 carrying a low-fitness cost resistance plasmid, previously observed in travel associated sublineages of S. flexneri. Our results highlight the persistent threat of horizontally transmitted antimicrobial resistance and the value of continuing to work towards early and open international sharing of genomic surveillance data.

Pangenome Analysis of a Salmonella Enteritidis Population Links a Major Outbreak to a Gifsy-1-Like Prophage Containing Anti-Inflammatory Gene gogB.

A major outbreak of the globally significant Salmonella Enteritidis foodborne pathogen was identified within a large clinical data set by a program of routine WGS of clinical presentations of salmonellosis in New South Wales, Australia. Pangenome analysis helped to quantify and isolate prophage content within the accessory partition of the pangenome. A prophage similar to Gifsy-1 (henceforth GF-1L) was found to occur in all isolates of the outbreak core SNP cluster, and in three other isolates. Further analysis revealed that the GF-1L prophage carried the gogB virulence factor. These observations suggest that GF-1L may be an important marker of virulence for S. Enteritidis population screening and, that anti-inflammatory, gogB-mediated virulence currently associated with Salmonella Typhimurium may also be displayed by S. Enteritidis. IMPORTANCE We examined 5 years of genomic and epidemiological data for the significant global foodborne pathogen, Salmonella enterica. Although Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) is the leading cause of salmonellosis in the USA and Europe, prior to 2018 it was not endemic in the southern states of Australia. However, in 2018 a large outbreak led to the endemicity of S. Enteritidis in New South Wales, Australia, and a unique opportunity to study this phenomenon. Using pangenome analysis we uncovered that this clone contained a Gifsy-1-like prophage harboring the known virulence factor gogB. The prophage reported has not previously been described in S. Enteritidis isolates.

Genomes of Vibrio cholerae O1 Serotype Ogawa Associated with Current Cholera Activity in Pakistan.

Here, this report presents two genomes of Vibrio cholerae O1 serotype Ogawa, recovered from cholera cases in Australia linked to travel to Pakistan in 2022. Their multidrug-resistant genotype represents the current activity of cholera within the seventh pandemic. One of the genome sequences was assembled using both short- and long-read sequences.

Case report: a genomics-guided reclassification of a blood culture isolate misassigned by MALDI-TOF as Yersinia pestis.

In this report, we describe a case where Gram-negative rods were isolated from a blood culture which subsequently presented a discordant Yersinia species result by MALDI-TOF. Rapid sequencing provided high-resolution identification of the isolate as Yersinia pseudotuberculosis , which was subsequently confirmed by biochemical tests.

Co-infection with SARS-CoV-2 Omicron and Delta variants revealed by genomic surveillance.

Co-infections with different variants of SARS-CoV-2 are a key precursor to recombination events that are likely to drive SARS-CoV-2 evolution. Rapid identification of such co-infections is required to determine their frequency in the community, particularly in populations at-risk of severe COVID-19, which have already been identified as incubators for punctuated evolutionary events. However, limited data and tools are currently available to detect and characterise the SARS-CoV-2 co-infections associated with recognised variants of concern. Here we describe co-infection with the SARS-CoV-2 variants of concern Omicron and Delta in two epidemiologically unrelated adult patients with chronic kidney disease requiring maintenance haemodialysis. Both variants were co-circulating in the community at the time of detection. Genomic surveillance based on amplicon- and probe-based sequencing using short- and long-read technologies identified and quantified subpopulations of Delta and Omicron viruses in respiratory samples. These findings highlight the importance of integrated genomic surveillance in vulnerable populations and provide diagnostic pathways to recognise SARS-CoV-2 co-infection using genomic data.

Added Value of Genomic Surveillance of Virulence Factors in Shiga Toxin-Producing Escherichia coli in New South Wales, Australia.

The disease caused by Shiga toxin-producing Escherichia coli (STEC) remains a significant public health challenge globally, but the incidence of human STEC infections in Australia remains relatively low. This study examined the virulence characteristics and diversity of STEC isolates in the state of New South Wales between December 2017 and May 2020. Utilisation of both whole and core genome multi-locus sequence typing (MLST) allowed for the inference of genomic diversity and detection of isolates that were likely to be epidemiologically linked. The most common STEC serotype and stx subtype detected in this study were O157:H7 and stx 1a, respectively. A genomic scan of other virulence factors present in STEC suggested interplay between iron uptake system and virulence factors that mediate either iron release or countermeasures against host defence that could result in a reduction of stx 1a expression. This reduced expression of the dominant stx genotype could contribute to the reduced incidence of STEC-related illness in Australia. Genomic surveillance of STEC becomes an important part of public health response and ongoing interrogation of virulence factors in STEC offers additional insights for the public health risk assessment.

Revealing COVID-19 transmission in Australia by SARS-CoV-2 genome sequencing and agent-based modeling.

In January 2020, a novel betacoronavirus (family Coronaviridae), named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified as the etiological agent of a cluster of pneumonia cases occurring in Wuhan City, Hubei Province, China1,2. The disease arising from SARS-CoV-2 infection, coronavirus disease 2019 (COVID-19), subsequently spread rapidly causing a worldwide pandemic. Here we examine the added value of near real-time genome sequencing of SARS-CoV-2 in a subpopulation of infected patients during the first 10 weeks of COVID-19 containment in Australia and compare findings from genomic surveillance with predictions of a computational agent-based model (ABM). Using the Australian census data, the ABM generates over 24 million software agents representing the population of Australia, each with demographic attributes of an anonymous individual. It then simulates transmission of the disease over time, spreading from specific infection sources, using contact rates of individuals within different social contexts. We report that the prospective sequencing of SARS-CoV-2 clarified the probable source of infection in cases where epidemiological links could not be determined, significantly decreased the proportion of COVID-19 cases with contentious links, documented genomically similar cases associated with concurrent transmission in several institutions and identified previously unsuspected links. Only a quarter of sequenced cases appeared to be locally acquired and were concordant with predictions from the ABM. These high-resolution genomic data are crucial to track cases with locally acquired COVID-19 and for timely recognition of independent importations once border restrictions are lifted and trade and travel resume.

Visualization of Phage Genomic Data: Comparative Genomics and Publication-Quality Diagrams.

The presentation of bacteriophage genomes as diagrams allows the location and organization of features to be communicated in a clear and effective manner. A wide range of software applications are available for the clear and accurate visualization of genomic data. Several of these applications incorporate comparative analysis tools, allowing for insertions, deletions, rearrangements and variations in syntenic regions to be visualized. In this chapter, freely available software and resources for the generation of high-quality graphical maps of bacteriophage genomes are listed and discussed.

Genomic Epidemiology of NDM-1-Encoding Plasmids in Latin American Clinical Isolates Reveals Insights into the Evolution of Multidrug Resistance.

Bacteria that produce the broad-spectrum Carbapenem antibiotic New Delhi Metallo-ß-lactamase (NDM) place a burden on health care systems worldwide, due to the limited treatment options for infections caused by them and the rapid global spread of this antibiotic resistance mechanism. Although it is believed that the associated resistance gene blaNDM-1 originated in Acinetobacter spp., the role of Enterobacteriaceae in its dissemination remains unclear. In this study, we used whole genome sequencing to investigate the dissemination dynamics of blaNDM-1-positive plasmids in a set of 21 clinical NDM-1-positive isolates from Colombia and Mexico (Providencia rettgeri, Klebsiella pneumoniae, and Acinetobacter baumannii) as well as six representative NDM-1-positive Escherichia coli transconjugants. Additionally, the plasmids from three representative P. rettgeri isolates were sequenced by PacBio sequencing and finished. Our results demonstrate the presence of previously reported plasmids from K. pneumoniae and A. baumannii in different genetic backgrounds and geographically distant locations in Colombia. Three new previously unclassified plasmids were also identified in P. rettgeri from Colombia and Mexico, plus an interesting genetic link between NDM-1-positive P. rettgeri from distant geographic locations (Canada, Mexico, Colombia, and Israel) without any reported epidemiological links was discovered. Finally, we detected a relationship between plasmids present in P. rettgeri and plasmids from A. baumannii and K. pneumoniae. Overall, our findings suggest a Russian doll model for the dissemination of blaNDM-1 in Latin America, with P. rettgeri playing a central role in this process, and reveal new insights into the evolution and dissemination of plasmids carrying such antibiotic resistance genes.

First Complete Providencia rettgeri Genome Sequence, the NDM-1-Producing Clinical Strain RB151.

Providencia rettgeri is an opportunistic bacterial pathogen of clinical significance due to its association with urinary tract infections and multidrug resistance. Here, we report the first complete genome sequence of P. rettgeri The genome of strain RB151 consists of a 4.8-Mbp chromosome and a 108-kbp blaNDM-1-positive plasmid.

Role of growth hormone-releasing hormone in dyslipidemia associated with experimental type 1 diabetes.

Dyslipidemia associated with triglyceride-rich lipoproteins (TRLs) represents an important residual risk factor for cardiovascular and chronic kidney disease in patients with type 1 diabetes (T1D). Levels of growth hormone (GH) are elevated in T1D, which aggravates both hyperglycemia and dyslipidemia. The hypothalamic growth hormone-releasing hormone (GHRH) regulates the release of GH by the pituitary but also exerts separate actions on peripheral GHRH receptors, the functional role of which remains elusive in T1D. In a rat model of streptozotocin (STZ)-induced T1D, GHRH receptor expression was found to be up-regulated in the distal small intestine, a tissue involved in chylomicron synthesis. Treatment of T1D rats with a GHRH antagonist, MIA-602, at a dose that did not affect plasma GH levels, significantly reduced TRL, as well as markers of renal injury, and improved endothelial-dependent vasorelaxation. Glucagon-like peptide 1 (GLP-1) reduces hyperglucagonemia and postprandial TRL, the latter in part through a decreased synthesis of apolipoprotein B-48 (ApoB-48) by intestinal cells. Although plasma GLP-1 levels were elevated in diabetic animals, this was accompanied by increased rather than reduced glucagon levels, suggesting impaired GLP-1 signaling. Treatment with MIA-602 normalized GLP-1 and glucagon to control levels in T1D rats. MIA-602 also decreased secretion of ApoB-48 from rat intestinal epithelial cells in response to oleic acid stimulation in vitro, in part through a GLP-1-dependent mechanism. Our findings support the hypothesis that antagonizing the signaling of GHRH in T1D may improve GLP-1 function in the small intestine, which, in turn, diminishes TRL and reduces renal and vascular complications.

Comment on "Climate sensitivity estimated from temperature reconstructions of the Last Glacial Maximum".

Schmittner et al. (Reports, 9 December 2011, p. 1385) report a new, low estimate of equilibrium climate sensitivity based on a comparison of Last Glacial Maximum climate model simulations and paleoproxy data. Here, we show that exclusion of questionable comparison points and constructive changes to model design are both likely capable of altering the most probable value of equilibrium climate sensitivity suggested in Schmittner et al.

Phylogenetically related Argentinean and Australian Escherichia coli O157 isolates are distinguished by virulence clades and alternative Shiga toxin 1 and 2 prophages.

Shiga toxigenic Escherichia coli O157 is the leading cause of hemolytic uremic syndrome (HUS) worldwide. The frequencies of stx genotypes and the incidences of O157-related illness and HUS vary significantly between Argentina and Australia. Locus-specific polymorphism analysis revealed that lineage I/II (LI/II) E. coli O157 isolates were most prevalent in Argentina (90%) and Australia (88%). Argentinean LI/II isolates were shown to belong to clades 4 (28%) and 8 (72%), while Australian LI/II isolates were identified as clades 6 (15%), 7 (83%), and 8 (2%). Clade 8 was significantly associated with Shiga toxin bacteriophage insertion (SBI) type stx(2) (locus of insertion, argW) in Argentinean isolates (P < 0.0001). In Argentinean LI/II strains, stx(2) is carried by a prophage inserted at argW, whereas in Australian LI/II strains the argW locus is occupied by the novel stx(1) prophage. In both Argentinean and Australian LI/II strains, stx(2c) is almost exclusively carried by a prophage inserted at sbcB. However, alternative q(933)- or q(21)-related alleles were identified in the Australian stx(2c) prophage. Argentinean LI/II isolates were also distinguished from Australian isolates by the presence of the putative virulence determinant ECSP_3286 and the predominance of motile O157:H7 strains. Characteristics common to both Argentinean and Australian LI/II O157 strains included the presence of putative virulence determinants (ECSP_3620, ECSP_0242, ECSP_2687, ECSP_2870, and ECSP_2872) and the predominance of the tir255T allele. These data support further understanding of O157 phylogeny and may foster greater insight into the differential virulence of O157 lineages.

Cytotoxicity of Tumor necrosis factor related apoptosis-inducing ligand towards Ewing's sarcoma cell lines.

Death ligands of the Tumor Necrosis Factor (TNF) family are known to induce apoptosis upon binding to their cognate receptors. However, the clinical utility of these cytokines as anticancer agents has been limited due to unacceptable toxicity. TRAIL is a recently isolated death ligand that possesses selective anti-tumor activity against a number of cancer cell lines without significant systemic toxicity. In this report we present evidence that cell lines derived from Ewing's Sarcoma (ES) are uniformly sensitive to TRAIL-mediated apoptosis. Furthermore, unlike TNF-alpha, treatment with TRAIL fails to induce the anti-apoptotic and pro-inflammatory NF-kappaB pathway in the ES cell lines. Our results suggest that TRAIL may prove to be a useful agent for the treatment of Ewing's sarcoma and related peripheral neuroectodermal tumors.

The ectodermal dysplasia receptor activates the nuclear factor-kappaB, JNK, and cell death pathways and binds to ectodysplasin A.

The ectodermal dysplasia receptor (EDAR) is a recently isolated member of the tumor necrosis factor receptor family that has been shown to play a key role in the process of ectodermal differentiation. We present evidence that EDAR is capable of activating the nuclear factor-kappaB, JNK, and caspase-independent cell death pathways and that these activities are impaired in mutants lacking its death domain or those associated with anhidrotic ectodermal dysplasia and the downless phenotype. Although EDAR possesses a death domain, it did not interact with the death domain-containing adaptor proteins TRADD and FADD. EDAR successfully interacted with various TRAF family members; however, a dominant-negative mutant of TRAF2 was incapable of blocking EDAR-induced nuclear factor-kappaB or JNK activation. Collectively, the above results suggest that EDAR utilizes a novel signal transduction pathway. Finally, ectodysplasin A can physically interact with the extracellular domain of EDAR and thus represents its biological ligand.

Activation of the NF-kappaB pathway by caspase 8 and its homologs.

Caspase 8 is the most proximal caspase in the caspase cascade and has been known for its role in the mediation of cell death by various death receptors belonging to the TNFR family. We have discovered that Caspase 8 can activate the NF-kappaB pathway independent of its activity as a pro-apoptotic protease. This property is localized to its N-terminal prodomain, which contains two homologous death effector domains (DEDs). Caspase 10 and MRIT, two DEDs-containing homologs of Caspase 8, can similarly activate the NF-kappaB pathway. Dominant-negative mutants of the Caspase 8 prodomain can block NF-kappaB induced by Caspase 8, FADD and several death receptors belonging to the TNFR family. Caspase 8 can interact with multiple proteins known to be involved in the activation of the NF-kappaB pathway, including the serine-threonine kinases RIP, NIK, IKK1 and IKK2. Thus, DEDs-containing caspases and caspase homolog(s) may have functions beyond their known role in the mediation of cell death. Oncogene (2000) 19, 4451 - 4460.