Shigella spp. are some of the key pathogens responsible for the global burden of diarrhoeal disease. These facultative intracellular bacteria belong to the family Enterobacteriaceae, together with other intestinal pathogens, such as Escherichia coli and Salmonella spp. The genus Shigella comprises four different species, each consisting of several serogroups, all of which show phenotypic similarity, including invasive pathogenicity. DNA sequencing suggests that this similarity results from the convergent evolution of different Shigella spp. founders. Here, we review the evolutionary relationships between Shigella spp. and E . coli, and we highlight how the genomic plasticity of these bacteria and their acquisition of a distinctive virulence plasmid have enabled the development of such highly specialized pathogens. Furthermore, we discuss the insights that genotyping and whole-genome sequencing have provided into the phylogenetics and intercontinental spread of Shigella spp.

The genomic signatures of Shigella evolution, adaptation and geographical spread

Sand amendment enhances bioelectrochemical remediation of petroleum hydrocarbon contaminated soil.

During the past two decades, the technological progress of whole-genome sequencing (WGS) had changed the fields of Environmental Microbiology and Biotechnology, and, currently, is changing the underlying principles, approaches, and fundamentals of Public Health, Epidemiology, Health Economics, and national productivity. Today’s WGS technologies are able to compete with conventional techniques in cost, speed, accuracy, and resolution for day-to-day control of infectious diseases and outbreaks in clinical laboratories and in long-term epidemiological investigations. WGS gives rise to an exciting future direction for personalized Genomic Epidemiology. One of the most vital and growing public health problems is the emerging and re-emerging of multidrug-resistant (MDR) bacterial infections in the communities and healthcare settings, reinforced by a decline in antimicrobial drug discovery. In recent years, retrospective analysis provided by WGS has had a great impact on the identification and tracking of MDR microorganisms in hospitals and communities. The obtained genomic data are also important for developing novel easy-to-use diagnostic assays for clinics, as well as for antibiotic and therapeutic development at both the personal and population levels. At present, this technology has been successfully applied as an addendum to the real-time diagnostic methods currently used in clinical laboratories. However, the significance of WGS for public health may increase if: (a) unified and user-friendly bioinformatics toolsets for easy data interpretation and management are established, and (b) standards for data validation and verification are developed. Herein, we review the current and future impact of this technology on diagnosis, prevention, treatment, and control of MDR infectious bacteria in clinics and on the global scale.

/pdf/whole-genome-sequencing-targets-drug-resistant-bacterial-2g0m9gply6.pdf

Whole-genome sequencing targets drug-resistant bacterial infections.

Despite a significant decrease in Shigella-related mortality, shigellosis continues to carry a significant burden of disease worldwide, particularly inAsia and Africa.Shigella is a highly virulent pathogen comprised of four major species with numerous subtypes. Shigella dysenteriae and Shigella flexneri infections are predominant in resource-limited set- tings. Clinical presentations range from mild watery diarrhea to severe dysentery with systemic complications such as elec- trolyte imbalance, seizures and hemolytic uremic syndrome. S. dysenteriae subtype 1, the producer of Shiga toxin, causes the most severe illness and highest mortality. Susceptible strains ofShigellamay be effectively treated with inexpensive oral antibiotics such as ampicillin or trimethoprim- sulfamethoxazole. Unfortunately, multidrug-resistant strains have emerged that have rendered most antibiotics, including fluoroquinolones and extended-spectrum cephalosporins, in- effective. Management and prevention of shigellosis repre- sents a major public health challenge. The development of an effective vaccine is urgently needed to decrease its global impact.

/pdf/shigella-a-highly-virulent-and-elusive-pathogen-2zl5wg2xof.pdf

Shigella: A Highly Virulent and Elusive Pathogen

An Escherichia coli O157:H7 outbreak in China in 1999 caused 177 deaths due to hemolytic uremic syndrome. Sixteen outbreak associated isolates were found to belong to a new clone, sequence type 96 (ST96), based on multilocus sequence typing of 15 housekeeping genes. Whole genome sequencing of an outbreak isolate, Xuzhou21, showed that the isolate is phylogenetically closely related to the Japan 1996 outbreak isolate Sakai, both of which share the most recent common ancestor with the US outbreak isolate EDL933. The levels of IL-6 and IL-8 of peripheral blood mononuclear cells induced by Xuzhou21 and Sakai were significantly higher than that induced by EDL933. Xuzhou21 also induced a significantly higher level of IL-8 than Sakai while both induced similar levels of IL-6. The expression level of Shiga toxin 2 in Xuzhou21 induced by mitomycin C was 68.6 times of that under non-inducing conditions, twice of that induced in Sakai (32.7 times) and 15 times higher than that induced in EDL933 (4.5 times). Our study shows that ST96 is a novel clone and provided significant new insights into the evolution of virulence of E. coli O157:H7.

/pdf/a-novel-escherichia-coli-o157-h7-clone-causing-a-major-4qm3vfkkop.pdf

A Novel Escherichia coli O157:H7 Clone Causing a Major Hemolytic Uremic Syndrome Outbreak in China

Shigella spp. are the causative agent of shigellosis with Shigella flexneri serotype 2a being the most prevalent in developing countries. Epidemiological surveillance in China found that a new serotype of S. flexneri appeared in 2001 and replaced serotype 2a in 2003 as the most prevalent serotype in Henan Province. The new serotype also became the dominant serotype in 7 of the 10 other provinces under surveillance in China by 2007. The serotype was identified as a variant of serotype X. It differs from serotype X by agglutination to the monovalent anti-IV type antiserum and the group antigen-specific monoclonal antibody MASF IV-I. Genome sequencing of a serotype X variant isolate, 2002017, showed that it acquired a Shigella serotype conversion island, also as an SfX bacteriophage, containing gtr genes for type X-specific glucosylation. Multilocus sequence typing of 15 genes from 37 serotype X variant isolates and 69 isolates of eight other serotypes, 1a, 2a, 2b, 3a, 4a, 5b, X, and Y, found that all belong to a new sequence type (ST), ST91. Pulsed-field gel electrophoresis revealed 154 pulse types with 655 S. flexneri isolates analyzed and identified 57 serotype switching events. The data suggest that S. flexneri epidemics in China have been caused by a single epidemic clone, ST91, with frequent serotype switching to evade infection-induced immunity to serotypes to which the population was exposed previously. The clone has also acquired resistance to multiple antibiotics. These findings underscore the challenges to the current vaccine development and control strategies for shigellosis.

Emergence of a New Multidrug-Resistant Serotype X Variant in an Epidemic Clone of Shigella flexneri

In addition to the large virulence plasmid pO157, a novel 38-kb conjugative plasmid, pO157_Sal, was identified and sequenced from an Escherichia coli O157:H7 outbreak-associated Chinese isolate that shares high similarity with a plasmid in Salmonella enterica serovar Agona. The plasmid was found in 15 of 326 isolates, 12 of which were of the same pulsed-field gel electrophoresis type.

pO157_Sal, a Novel Conjugative Plasmid Detected in Outbreak Isolates of Escherichia coli O157:H7

The present invention discloses a cyclone in-orbit gas-liquid separation apparatus, which can achieve gas and liquid separation in a microgravity environment. The designed cyclone in-orbit gas-liquid separation apparatus comprises a circle of spiral pipeline and two branch pipelines, wherein the cross section of the pipeline is circular, a separation plate is arranged inside the pipeline, the cross section of the pipeline is divided into two semi-circular cross sections after flowing a circle, and two leading-out pipe are respectively used for leading a liquid propellant and gas. The cyclone on-track gas-liquid separation apparatus of the present invention has characteristics of high efficiency and strong anti-interference capability, and provides a novel simple and efficient gas-liquid separation method for propellant in-orbit supply.

Cyclone in-orbit gas-liquid separation apparatus

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Emergence of a New Multidrug-Resistant Serotype X Variant in an Epidemic Clone of Shigella flexneri

pO157_Sal, a Novel Conjugative Plasmid Detected in Outbreak Isolates of Escherichia coli O157:H7

Cyclone in-orbit gas-liquid separation apparatus