Identification and characterization of the novel colonization factor CS30 based on whole genome sequencing in enterotoxigenic Escherichia coli (ETEC).

The ability to colonize the small intestine is essential for enterotoxigenic Escherichia coli (ETEC) to cause diarrhea. Although 22 antigenically different colonization factors (CFs) have been identified and characterized in ETEC at least 30% of clinical ETEC isolates lack known CFs. Ninety-four whole genome sequenced "CF negative" isolates were searched for novel CFs using a reverse genetics approach followed by phenotypic analyses. We identified a novel CF, CS30, encoded by a set of seven genes, csmA-G, related to the human CF operon CS18 and the porcine CF operon 987P (F6). CS30 was shown to be thermo-regulated, expressed at 37 °C, but not at 20 °C, by SDS-page and mass spectrometry analyses as well as electron microscopy imaging. Bacteria expressing CS30 were also shown to bind to differentiated human intestinal Caco-2 cells. The genes encoding CS30 were located on a plasmid (E873p3) together with the genes encoding LT and STp. PCR screening of ETEC isolates revealed that 8.6% (n = 13) of "CF negative" (n = 152) and 19.4% (n = 13) of "CF negative" LT + STp (n = 67) expressing isolates analyzed harbored CS30. Hence, we conclude that CS30 is common among "CF negative" LT + STp isolates and is associated with ETEC that cause diarrhea

Publisher Correction: Identification and characterization of the novel colonization factor CS30 based on whole genome sequencing in enterotoxigenic Escherichia coli (ETEC).

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Comparative Genomics and Characterization of Hybrid Shigatoxigenic and Enterotoxigenic Escherichia coli (STEC/ETEC) Strains

Background Shigatoxigenic Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC) cause serious foodborne infections in humans. These two pathogroups are defined based on the pathogroup-associated virulence genes: stx encoding Shiga toxin (Stx) for STEC and elt encoding heat-labile and/or est encoding heat-stable enterotoxin (ST) for ETEC. The study investigated the genomics of STEC/ETEC hybrid strains to determine their phylogenetic position among E. coli and to define the virulence genes they harbor. Methods The whole genomes of three STEC/ETEC strains possessing both stx and est genes were sequenced using PacBio RS sequencer. Two of the strains were isolated from the patients, one with hemolytic uremic syndrome, and one with diarrhea. The third strain was of bovine origin. Core genome analysis of the shared chromosomal genes and comparison with E. coli and Shigella spp. reference genomes was performed to determine the phylogenetic position of the STEC/ETEC strains. In addition, a set of virulence genes and ETEC colonization factors were extracted from the genomes. The production of Stx and ST were studied. Results The human STEC/ETEC strains clustered with strains representing ETEC, STEC, entero-aggregative E. coli, and commensal and laboratory-adapted E. coli. However, the bovine STEC/ETEC strain formed a remote cluster with two STECs of bovine origin. All three STEC/ETEC strains harbored several other virulence genes, apart from stx and est, and lacked ETEC colonization factors. Two STEC/ETEC strains produced both toxins and one strain Stx only. Conclusions This study shows that pathogroup-associated virulence genes of different E. coli can coexist in strains originating from different phylogenetic lineages. The possibility of virulence genes to be associated with several E. coli pathogroups should be taken into account in strain typing and in epidemiological surveillance. Development of novel hybrid E. coli strains may cause a new public health risk, which challenges the traditional diagnostics of E. coli infections.Peer reviewe

Winter tyres : Traffic safety

During the winter 1993/94, the Swedish National Road Administration received considerable criticism for its winter maintenance and in particular for the high consumption if road salt. This led to discussions on changing the rules for winter maintenance. Some ice or snow was temporary allowed on the roads with high winter maintenance standard. More roads were degraded to lower winter maintenance standard where ice or snow were permanently permitted. In addition, certain changes intended to influence driver behaviour and vehicle equipment for example mandating the use of winter tyres were to be studied. The purpose of the first investigation described in this paper was to calculate the socio-economic consequences that may be expected from a requirement on winter tyres in various circumstances. In the second investigation in this paper the traffic safety effect of the requirement is studied. A requirement of using winter tyres when it is slippery was selected based on facts from the first investigation

The effect of the Winter Tyre Law on the use of tyres and on accidents

Syftet med detta projekt är att få en första indikation på hur däckanvändningen och trafiksäkerheten förändrats då lagen infördes om att personbil, lätt lastbil och buss med en totalvikt av högst 3,5 ton under perioden 1 december till och med 31 mars vid färd på väg ska vara försedd med vinterdäck eller likvärdig utrustning då vinterväglag råder. Lagen började gälla 1 december 1999. Däckanvändningen har undersökts på parkeringsplatser i Östergötland. Förutom typ av däck (sommardäck/vinterdäck utan dubb/vinterdäck med dubb) noterades även tillverkningsår, mönsterdjup och dubbutstick. Trafiksäkerhetseffekten av olika däckanvändning går inte att undersöka direkt eftersom inte uppgifter om däck finns med i olycksdata. Effekten undersöktes därför genom att två vintrar före införandet av lagen jämfördes med de två vintrar som gått med krav på vinterdäck. För att kunna reducera inverkan av andra förändringar utnyttjades kontrollområden. I norra Sverige hade i stort sett alla personbilar vinterdäck innan lagen. Det skulle därmed endast bli en liten förändring av däckinnehavet. Norra Sverige kan därför utnyttjas som kontrollområde. För att även få ett kontrollområde i söder kontaktades Danmark, som inte heller haft någon förändring i däckanvändning, om det var möjligt att få utnyttja data därifrån. För att ytterligare ringa in effekten av däcklagen exkluderades de vägar i Sverige som under perioden infört en speciell vinterhastighetsgräns. Det som därmed blev provområden är södra Sverige upp till en linje norr om landskapen Bohuslän och Uppland.The aim of this project is to arrive at a preliminary indication of how the use of tyres and traffic safety were changed when the Law on winter tyres was in force; this Law directs that cars, light lorries and buses, of a total weight not exceeding 3.5 tonnes, shall during the period 1 December-31 March, when travelling on a road, be fitted with winter tyres or similar equipment when winter road conditions prevail. This Law came into force on 1 December 1999. The use of tyres was investigated at parking sites in Östergötland. Apart from the type of tyre (summer tyres/winter tyres without studs/winter tyres with studs), the year of manufacture, tread depth and stud protrusion were also noted. The traffic safety effect of the use of different tyres cannot be investigated directly since information concerning tyres is not included in accident data. The effect was therefore investigated by comparing two winters before the introduction of the Law with two winters when the requirement concerning winter tyres was in force. In order to reduce the influence of other changes, control areas were used. In the north of Sweden, practically all cars had winter tyres before the Law. There should therefore be only a small change in tyre use. Northern Sweden can therefore be used as a control area. In order that there should also be a control area in the south, a request was made to Denmark, where there had also been no change in tyre use, if it would be possible to utilise data from there. In order that the effect of the Tyre Law should be further elucidated, the roads in Sweden where a special winter speed limit was in force during the period concerned were also excluded. Southern Sweden up to a line to the north of the counties of Bohuslän and Uppland was therefore used as test areas.

Bus accidents in wintertime

Buses in Sweden have a low accident risk. However, statistics from 1996 - 2002 indicate that the number of bus accidents in Sweden with personal injuries have been increasing by 4% yearly. Buses also have a higher percentage of accidents that occur on ice/snow covered roads than other vehicles. In Sweden passenger cars must be equipped with winter tyres during the winter period. There is no such regulation for heavy vehicles, and many buses are using summer tyres all around the year. The present project had the purpose of looking at the bus-winter problem in more detail, with the main focus on tyres. Four different studies were carried out: tyre tests, focus group discussions, driving simulator tests and an accident study. Here is given a short summary concerning methods and conclusions of each sub project. Tyre tests on smooth ice did not show any significant difference between summer tyres and non-studded winter tyres, while studded tyres exhibits a better ice grip than non-studded tyres. Nor did driving simulator tests with driving on ice covered road under the influence of heavy wind from the side show a difference between summer tyres and non-studded winter tyres. Also in these tests studded tyres were superior to non-studded. Accident statistics indicate that buses with summer tyres on the steering axle and winter tyres on the drive axle have the lowest estimated accident risk, which is in accordance with the results in a previous study. The results are however not statistically significant due the low number of accidents. Three focus groups were carried out and the importance of the tyres for traffic safety during winter was discussed. It is however hard from the gathered discussion material to estimate just how important the tyres really are. The results do not warrant a winter tyre regulation for heavy vehicles, and a restriction of the use of studded tyres for buses would probably have negative consequences on traffic safety

Analysis of the Swedish National Road Administration’s and Banverket’s proposals regarding operation and maintenance strategies

Regeringen har gett väg- och transportforskningsinstitutet i uppdrag att granska innehållet i de förslag till drift- och underhållsstrategier för 2004–2015 som Vägverket och Banverket skickat på remiss. Denna rapport innehåller en redovisning av detta uppdrag. Gemensamt för båda trafikverken är det omfattande kunskapsmaterial i form av beskrivningar av vägnätets och bannätets standard som finns tillgängligt för planeringsarbetet. Man har i viktiga delar också kompletterat detta material med särskilda studier, enkäter och genom att låta regionerna bearbeta speciella frågor. Enligt instruktionerna från Näringsdepartementet ska verken utforma sina åtgärdsförslag för att minimera den samhällsekonomiska kostnaden för att hålla infrastruktur tillgänglig för trafik. Kriterier för när åtgärder ska sättas in – vad som av Vägverket kallas målnivåer – bör därför väljas med denna utgångspunkt. Problemet är att det är svårt och många gånger omöjligt att med utgångspunkt från tillgänglig dokumentation avgöra hur målnivåerna valts, om det skett på samhällsekonomiska grunder eller om det är andra överväganden som varit vägledande för att komma fram till dessa gränsvärden. Det har därför inte varit möjligt att som en del av granskningen komma fram till om man gjort rimliga avvägningar mellan olika aspekter på driftinsatserna.The Government has assigned the Swedish Road and Transport Research Institute the task of analysing the content of the proposals for operation and maintenance strategies that the Swedish National Road Administration and Banverket (the Swedish National Rail Administration) have submitted for comment. This memorandum constitutes a report of this assignment. Common to both the traffic administrations is the extensive knowledge in the form of descriptions of the road and rail networks\u92 standard that are available when planning. Important parts of this material have also been supplemented with studies and surveys, and by having the regions themselves work on special issues. According to the directives of the Ministry of Industry, Employment and Communications, the two administrations are to devise their own proposals for measures to minimise the cost to the public economy of keeping the infrastructure accessible for traffic. The criteria for when measures are to be applied \u96 which the National Road Administration calls target levels \u96 should therefore be chosen on this basis. The problem here is that it is difficult, and in many cases impossible, on the basis of the available documentation, to determine how the target levels have been chosen, whether this has been done according to public economy principles, or if other considerations have been the guiding principles when determining these limits. For these reasons, it has not been possible in our analysis to ascertain whether a reasonable balance has been achieved between different aspects of the measures proposed with regard to operation.

Traffic safety of buses winter time

Earlier studies have shown that buses are overrepresented at accidents during winter road conditions compared to other vehicle types. Hence, the traffic safety of buses during the wintertime has been studied in more detail. The study comprised the following parts: - Gripping power studies on ice in VTI's tyre test facility. - Accident study and a survey of the use of tyre. - Focus group to gain knowledge about dangerous situations. - Driving simulator study to test the importance of the tyres during problematic situations. Tests in VTI's tyre test facility on smooth ice did not show any significant difference between summer tyres and non-studded winter tyres, while studded tyres exhibit a better ice grip than non-studded tyres. Nor did driving simulator tests when driving on ice covered road under the influence of heavy wind from the side show a difference between summer tyres and non-studded winter tyres. Also in these tests the studded tyres were superior to the non-studded. If studded tyres are used only on one axle, the driving simulator study showed that during side wind the ability to steer is important. The accident study showed that the buses that have summer tyres on the steering axle and winter tyres on the drivé axle has the lowest estimated accident risk, although it is not statistically significant. The buses equipped with studded tyres on both axles could not be statistically analysed since only 2 accidents occurred on bare roadways, and none on icy/snowy roadways, while at the same time the buses in this category drive a lot on icy/snowy roadways. This probably makes these buses the safest on winter roadways. From the focus groups it was clear that the time table has a great influence on the creating of stress and the demands on the drivers to keep the speed even during slippery roadways. Many bus drivers experience large problems with bad snow clearance, or other winter maintenance. At the same time there is a large consciousness among the drivers that it is always their own way of handling the vehicle that is the determining factor for traffic safety. The drivers were expressing a lack of further education and practical exercises with buses on slippery roads

Tunga fordons däckanvändning : effekter vid is/snöväglag

I utredningen om det i Sverige ska bli ett krav på vinterdäck även för tunga fordon har följande delprojekt ingått. -\u95 Litteraturstudie. -\u95Kartläggning av tunga fordons däck, dess kvalitet och utnyttjande. -\u95Isgrepp. -\u95Köregenskaper. -\u95Olycksstudie. -\u95Ekonomiska konsekvenser av ett krav. Litteraturstudien visade hur betydelsefullt det är att ha bra däck både vad avser typ och kvalitet. Projektet fortsatte med att undersöka olika däcks isgrepp. Dubbdäck hade bäst väggrepp. Sajpning (tvärgående snitt i slitbanan) bidrar till goda glidfriktionsegenskaper hos däck utan dubbar. Det var stora skillnader i friktionsegenskaper mellan bästa och sämsta odubbade däck. Stabilitet, styr- och bromsegenskaper undersöktes vid körning på ett isbelagt flygfält. Dubbade vinterdäck på alla hjul gav klart bättre bromsförmåga än odubbade vinterdäck på alla hjul. Nya vinterdäck gav något bättre bromsförmåga än halvslitna sommardäck. Väjningsförmågan vid optimal styrning skilde sig inte tydligt mellan de olika alternativen När fordon var inne på Bilprovningen för besiktning delades enkäter ut till samtliga förare av tunga fordon på vissa utvalda platser spridda över hela landet. Det framgår av enkäterna att det är på drivaxeln som man främst använder vinterdäck (cirka 60 %). Framaxeln och släpen har oftast sommardäck. Dubbdäcksanvändningen är låg. Olycksdata från Vägverket har kompletterats med bl.a. däckdata genom att sända ut enkäter till ägare av tunga fordon som varit inblandade i olyckor under vintern 1998-99. Resultaten ger inget stöd för att dra några slutsatser beträffande bättre trafiksäkerhet om vinterdäck används på is- eller snöväglag. Studierna av isgrepp och köregenskaper visar att om inte beteendet ändrades med däckinnehav skulle det bli en trafiksäkerhetsförbättring på is/snöväglag då man byter från sommardäck till vinterdäck. Detta innebär att det efter denna utredning inte finns argument för att införa ett krav på vinterdäck för tunga fordon. Däck till tunga fordon borde dock förbättras så att de får samma väggrepp som däck till lätta fordon.The following subprojects were included in the investigation into whether the use of winter tyres on heavy vehicles should be a legal requirement in Sweden: \u95 A literary study. \u95 A survey of heavy vehicle tyres, their quality and use. \u95 Gripping power on ice. \u95 Driving properties. \u95 An accident survey. \u95 Economic consequences of a legal requirement. The literary study showed the importance of having good quality tyres of the right type. The project then went on to examine the gripping power on ice of a range of tyres. Studded tyres had the best gripping power. Sipes (transverse cuts in the tyre tread) contribute to good sliding friction properties in unstudded tyres. There were considerable differences in friction properties of the best and worst quality unstudded tyres. Stability, steering and braking properties were studied in test drives on an ice-covered airfield. Studded winter tyres on all wheels delivered far greater braking capacity than unstudded tyres on all wheels. New winter tyres provided much greater braking capacity than half worn summer tyres. There was no significant difference between the alternatives as regards lateral evasion maneuver capacity during optimal steering. When vehicles were undergoing inspection at the test station, questionnaires were distributed to all heavy vehicle drivers at selected locations across the country. The questionnaires indicate that winter tyres are primarily used on the wheels on the driving axel (approximately 60%). Summer tyres are most frequently used on the wheels on the front axles and trailers. The use of studded tyres is low. Accident data from the National Swedish Road Administration has been supplemented by sending out questionnaires to heavy vehicle owners involved in accidents during the winter of 1998-99. The results do not make it possible to draw any conclusions regarding improved levels of road safety should winter tyres be used in icy and snowy road conditions. Studies of gripping power on ice and driving properties show that if driver behaviour did not change with tyre selection, the change from summer to winter tyres would enhance road safety on icy and snowy roads. This means that after this investigation there can be no argument for introducing a legal requirement regarding the use of winter tyres for heavy vehicles. Heavy vehicle tyres should however be improved so that they have the same gripping power as the tyres of light vehicles