Salmonella enterica subspecies enterica is traditionally subdivided into serovars by serological and nutritional characteristics. We used Multilocus Sequence Typing (MLST) to assign 4,257 isolates from 554 serovars to 1092 sequence types (STs). The majority of the isolates and many STs were grouped into 138 genetically closely related clusters called eBurstGroups (eBGs). Many eBGs correspond to a serovar, for example most Typhimurium are in eBG1 and most Enteritidis are in eBG4, but many eBGs contained more than one serovar. Furthermore, most serovars were polyphyletic and are distributed across multiple unrelated eBGs. Thus, serovar designations confounded genetically unrelated isolates and failed to recognize natural evolutionary groupings. An inability of serotyping to correctly group isolates was most apparent for Paratyphi B and its variant Java. Most Paratyphi B were included within a sub-cluster of STs belonging to eBG5, which also encompasses a separate sub-cluster of Java STs. However, diphasic Java variants were also found in two other eBGs and monophasic Java variants were in four other eBGs or STs, one of which is in subspecies salamae and a second of which includes isolates assigned to Enteritidis, Dublin and monophasic Paratyphi B. Similarly, Choleraesuis was found in eBG6 and is closely related to Paratyphi C, which is in eBG20. However, Choleraesuis var. Decatur consists of isolates from seven other, unrelated eBGs or STs. The serological assignment of these Decatur isolates to Choleraesuis likely reflects lateral gene transfer of flagellar genes between unrelated bacteria plus purifying selection. By confounding multiple evolutionary groups, serotyping can be misleading about the disease potential of S. enterica. Unlike serotyping, MLST recognizes evolutionary groupings and we recommend that Salmonella classification by serotyping should be replaced by MLST or its equivalents.

/pdf/multilocus-sequence-typing-as-a-replacement-for-serotyping-51v3t9tnj6.pdf

Multilocus Sequence Typing as a Replacement for Serotyping in Salmonella enterica

INTRODUCION................................................................ 193 STUDIES ON 0 ANTIGENS...................................................... 196 Isolation and Properties of O-Specific Preparations from Bacteria.................. 196 Trichloroacetic acid extraction of the whole \"Boivin\" antigen.................... 196 Extraction of lipopolysaccharides with phenol-water, aqueous ether, and similar methods.................................................. ............. 196 Extraction ofpolysaccharides with sodium hydroxide: alkali polysaccharide ...... 197 Extraction ofpolysaccharide by acetic acid: degraded Freeman polysaccharide...... 197 Physical and biological properties of 0-specific preparations..................... 197 Sugar Constituents of the Specific Polysaccharides.............................. 198 6-Deoxyhexoses........................................................... 199 3, 6-Dideoxyhexoses ...................................................... 199 Heptoses................................................................. 200 Hexosamines.............................................................. 200 Ribose.................................................................. 200 2-Keto-3-deoxy-octonate (KDO)............................................. 200 0-phosphorylethanolamine.................................................. 201 Sugar Composition ofSpecific Polysaccharides.................................. 201 Structure of the O-Specific Side Chain.......................................... 204 Salmonella ofgroup DI ................. .................................... 204 Salmonella ofgroup B ............... ...................................... 205 Salmonella ofgroups E1 (3, 10), E2 (3, 15), E3 (3, 15, 34), and E4 (1, 3, 19) ......... 206 Salmonella of groups G (13, 22), N (30), and U (43) ...... .................... 206 Structure of 0 Factors in Specific Polysaccharides.............................. 206 Role of 3,6-dideoxyhexoses: 0 factors 2, 4, 8, 9, 35, 50........................ 207 Artificial antigens......................................................... 209 Factor 5................................................................. 209 Factors 1, 112, 19, 37....................................................... 210 Factors 3, 10, 15, and 34 .............. ..................................... 211 Factor 12........... .. .. ... .. ... .. ... ............................ 212 Location of the factors on the chain........................................ 212 Biochemical and Genetic Basis of Changes in Specificity After Phage Conversion .... 214 Appearance offactor 1..................................................... 215 Conversions in group E..................................................... 216 Appearance of factors 27A, 27B, and 27D in groups A, B, and D after conversion byphage27............................................................ 216 STUDIES ON R ANTIGENS...................................................... 219 Preparation and Composition of R (Lipo)polysaccharides........................ 221 R Mutants ofChemotype Ra (Serotype R II Mutants) ...... ...................... 221 Chemical structure ........................................................ 223 Enzymatic defects......................................................... 225 R Mutants of Chemotype Rb (Serotype R I Mutants)............................. 227 Serology.................................................................. 227 Chemical structure ........................................................ 227 Enzymatic defects......................................................... 227 0-specific polysaccharide hapten ofR I mutants ....... ......................... 228 R Mutants ofChemotype Rc (M Mutants) ........ .............................. 228 Enzymatic defects and biochemical properties.................................. 228 Chemical analysis ofchemotype Rc lipopolysaccharides......................... 229 Accumulation ofnucleoside diphospho sugars in M mutants...................... 229 R Mutants of Chemotype Rd.................................................. 230 R Mutants of Chemotype Re.................................................. 230 Salmonella T Forms......................................................... 231 Semirough Forms ........... ................................................ 231 Genetics ofR Mutants ...................................................... 232

https://mmbr.asm.org/content/mmbr/30/1/192.full.pdf

Immunochemistry of O and R antigens of Salmonella and related Enterobacteriaceae.

Current data from bacterial pathogens of animals and from bacterial symbionts of plants support some of the more general proposed functions for lipopolysaccharides (LPS) and underline the importance of LPS structural versatility and adaptability. Most of the structural heterogeneity of LPS molecules is found in the O-antigen polysaccharide. In this review, the role and mechanisms of this striking flexibility in molecular structure of the O-antigen in bacterial pathogens and symbionts are illustrated by some recent findings. The variation in O-antigen that gives rise to an enormous structural diversity of O-antigens lies in the sugar composition and the linkages between monosaccharides. The chemical composition and structure of the O-antigen is strain-specific (interstrain LPS heterogeneity) but can also vary within one bacterial strain (intrastrain LPS heterogeneity). Both LPS heterogeneities can be achieved through variations at different levels. First of all, O-polysaccharides can be modified non-stoichiometrically with sugar moieties, such as glucosyl and fucosyl residues. The addition of non-carbohydrate substituents, i.e. acetyl or methyl groups, to the O-antigen can also occur with regularity, but in most cases these modifications are again non-stoichiometric. Understanding LPS structural variation in bacterial pathogens is important because several studies have indicated that the composition or size of the O-antigen might be a reliable indicator of virulence potential and that these important features often differ within the same bacterial strain. In general, O-antigen modifications seem to play an important role at several (at least two) stages of the infection process, including the colonization (adherence) step and the ability to bypass or overcome host defense mechanisms. There are many reports of modifications of O-antigen in bacterial pathogens, resulting either from altered gene expression, from lysogenic conversion or from lateral gene transfer followed by recombination. In most cases, the mechanisms underlying these changes have not been resolved. However, in recent studies some progress in understanding has been made. Changes in O-antigen structure mediated by lateral gene transfer, O-antigen conversion and phase variation, including fucosylation, glucosylation, acetylation and changes in O-antigen size, will be discussed. In addition to the observed LPS heterogeneity in bacterial pathogens, the structure of LPS is also altered in bacterial symbionts in response to signals from the plant during symbiosis. It appears to be part of a molecular communication between bacterium and host plant. Experiments ex planta suggest that the bacterium in the rhizosphere prepares its LPS for its roles in symbiosis by refining the LPS structure in response to seed and root compounds and the lower pH at the root surface. Moreover, modifications in LPS induced by conditions associated with infection are another indication that specific structures are important. Also during the differentiation from bacterium to bacteroid, the LPS of Rhizobium undergoes changes in the composition of the O-antigen, presumably in response to the change of environment. Recent findings suggest that, during symbiotic bacteroid development, reduced oxygen tension induces structural modifications in LPS that cause a switch from predominantly hydrophilic to predominantly hydrophobic molecular forms. However, the genetic mechanisms by which the LPS epitope changes are regulated remain unclear. Finally, the possible roles of O-antigen variations in symbiosis will be discussed.

http://dzumenvis.nic.in/Microbes%20and%20Metals%20Interaction/pdf/O-antigen%20structural%20variation.pdf

O-antigen structural variation: mechanisms and possible roles in animal/plant-microbe interactions.

Crude cell extracts of 26 isolates of Salmonella serotype typhi (S. typhi) and 48 other Salmonella isolates representing 28 serotypes and seven DNA hybridization subgroups were analyzed for electrophoretic variants of 24 metabolic enzymes by starch gel electrophoresis. All strains of S. typhi had identical isoenzyme patterns, indicating that they were a single clone. All of the enzymes detected in the remaining strains were polymorphic, and the degree of genetic variation was quite high. The average number of alleles per enzyme locus was 4.7, and the mean genetic diversity per locus was 0.556. Thirty-two distinct allele profiles, or electrophoretic types (ETs), were found in these 48 strains of Salmonella serotypes other than S. typhi. Analysis of the genetic relationships of the ETs to each other showed that, with one exception, the ETs formed subgroups that were consistent with the subgroupings based on DNA hybridization studies. ET profiles were not always linked to specific serologic patterns. These data show that multilocus enzyme electrophoresis has a potential application in epidemiologic and taxonomic studies of salmonellae, although it is not differential for S. typhi. We also propose a new species, Salmonella bongori comb. nov., a new combination base on the elevation of Salmonella choleraesuis subsp. bongori to the level of species.

Clonal nature of Salmonella typhi and its genetic relatedness to other salmonellae as shown by multilocus enzyme electrophoresis, and proposal of Salmonella bongori comb. nov.

Crudecell extracts of26isolates ofSalmonella serotype typhi (S.typhi) and48otherSalmonella isolates representing 28serotypes andsevenDNA hybridization subgroups wereanalyzed forelectrophoretic variants of24metabolic enzymesbystarch gelelectrophoresis. Ailstrains ofS.typhi hadidentical isoenzyme patterns, indicating that they were asingle clone. Alloftheenzymesdetected intheremaining strains were polymorphic, andthedegree ofgenetic variation was quite high. Theaveragenumberofalleles perenzyme locus was 4.7, andthemean genetic diversity perlocus was 0.556. Thirty-two distinct allele profiles, orelectrophoretic types (ETs), were foundinthese 48strains ofSalmonella serotypes other thanS.typhi. Analysis ofthegenetic relationships oftheETstoeachother showedthat, with one exception, theETsformed subgroups that were consistent withthesubgroupings based on DNA hybridization studies. ETprofiles were notalways linked to specific serologic patterns. Thesedatashowthatmultilocus enzyme electrophoresis hasa potential application inepidemiologic andtaxonomic studies ofsalmonella, although itisnotdifferential forS.typhi. We also proposea new species, Salmonella bongori comb. nov.,a new combination based ontheelevation ofSalmonella choleraesuis subsp. bongori tothelevel ofspecies. Typhoid feverisstill an important infectious disease in mostoftheunderdeveloped world; however, theincidence oftyphoid feverintheUnited States hasdeclined forseveral decades, presumably because ofgoodsanitation practices andtreatment ofcarriers.Casesdooccur(6), andthere isa continuing needtoidentify isolates ofepidemiologic importance.Theprimary methods usedfordifferentiating strains ofSalmonella serotype typhi (S.typhi) arephagetyping (17), biotyping (27), andcolicin production (21). Ofthese, phage typing hasproved themostuseful (16); however, 4to5%of isolates arenontypeable bythis method, andalarge number ofisolates (upto25%)areofa single phagetype.Allofthe techniques usedtodifferentiate strains ofS. typhi probably measure very-short-term evolutionary distances. Forexample, a strain ofS.typhi phagetypeFlcan change tophage typeF2through theacquisition ofa single prophage, b2(1). Forthis reasonwe wantedtostudystrains ofthetyphoid bacillus andother Salmonella strains witha technique that woulddetect greaterevolutionary distance. Strains ofS. typhi havebeenfoundtobehighly related byDNA-DNA hybridization (7,18,19)buthavenotbeenstudied by techniques, suchas isoenzyme electrophoresis (29), that measure more subtle genetic differences. Thenumberofisolates ofotherSalmonella serotypes reported viatheSalmonella surveillance systemhasincreased inthelast 30years(6). Thisincrease isthought to reflect a realchangeintheincidence ofdisease, butthe reasonsfortheincrease arenotwellunderstood. Salmonellaecan bedivided intosubgroups bystandard immunologic andbiochemical methods(9),whichhaveepidemiologic value, buttheevolutionary significance ofthese phenotypic

Clonal Nature ofSalmonella typhi andItsGenetic Relatedness to OtherSalmonellae as ShownbyMultilocus EnzymeElectrophoresis, andProposal ofSalmonella bongori comb.nov.

Epidemiological markers of strains ofSalmonella are classified as major or minor. Major epidemiological markers are determined by chromosomal genes and are not affected by extrachromosomal elements. They are subspecies and serovars. Minor epidemiological markers are either affected by extrachromosomal replicons or have an insufficiently proven genetic stability and are used to subdivide serovars in detailed epidemiological investigations. These minor markers are biovars, phagovars, bacteriocinovars, patterns of resistance to antimicrobial agents, and restriction patterns of chromosomal and plasmid DNA.

Typing of Salmonella species.

Summary A new Salmonella subspecies designated as S. choleraesuis subsp. indica (shortly, subspecies VI) was delineated on the basis of biochemical characters and genomic relatedness. Eight serovars were assigned to this subspecies: one of these was previously classified in subspecies I (serovar Ferlac) and seven in subspecies II. This subspecies can be identified by five biochemical characters: gelatinase + , malonate − , L(+)tartrate − , salicin − and sorbitol si−. The type strain is CIP 102501 (serovar 1,6,14,25:a:e,n,x formerly called Ferlac).

Individualisation d'une septième sous-espèce de Salmonella: S.choleraesius subsp. indica subsp. nov.

Individualisation d'une septième sods-espèce de salmonella: s. choleraesuis subsp. indica subsp. nov.

Summary Salmonella serovar Tonev (antigenic formula, 21,54:b:e,n,x) is classifiedin the Salmonella group O:54, and contains a 7.5-kilobase plasmid, designated pIP1340. Tonev NV, a variant lacking pIP1340, failed to express O:54 (antigenic formula identical with that of serovar Minnesota, 21:b:e,n,x). Phenotypic tagging of plasmid pIP1340 by transposon Tn5 produced plasmid pIP1341. Factor O:54 expression in Tonev NV was restored after transformation by pIP1341 NDA or after co-transformation by a mixture of pBR322 and pIP1340 DNA. Similarly, the twelve other serovars presently classified in Salmonella group O:54 harboured a small plasmid which was not detectable in isogenic O:54-negative variants isolated from the parent strain. Transfer of plasmid pIP1341 into thes O:54-negative variants and also into reference strains of serovars of Salmonella group O:4 (Banana and Typhimurium), group O:7 (Thompson and Mbandaka), group O:8 (Ferruch, Hadar and Kentucky), group O:3,10 (Orion) and group O:21 (Minnesota) supported the conclusion that plasmid pIP1340 encodes or regulates some functions required for factor O:54 expression by various serovars of Salmonella.

Expression of antigenic factor O:54 is associated with the presence of a plasmid in Salmonella.

Preparation and Immunological Properties of an Artificial Antigen with Colitose (3-Deoxy-L-Fucose) as the Determinant Group

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

L. Le Minor

Author Tools

Chat about Author