CIVETAN   23983
CENTRO DE INVESTIGACION VETERINARIA DE TANDIL
Unidad Ejecutora - UE
artículos
Título:
Shigatoxin producing Escherichia coli in human, cattle, and foods. Strategies for detection and control.
Autor/es:
PADOLA, NORA LÍA.; ETCHEVERRÍA ANALÍA
Revista:
Frontiers in cellular and infection microbiology
Editorial:
Frontiers Editorial
Referencias:
Lugar: Lausanne; Año: 2014
Resumen:
Shiga toxin-producing E. coli (STEC) alsoknownas ?verocytotoxin-producing E. coli,?refersto E. coli pathotypescapableofproducingShigatoxintype1( Stx1),type2 (Stx2), orboth,encodedby stx1 and stx2genes,respectively (PatonandPaton,1998). ThegenesencodingStxarecarried by temperatebacteriophagesinsertintobacterialgenomaso that Stxproductionislinkedtotheinductionofthephage lyticcycle(O?LoughlinandRobins-Browne,2001). STx2isthe toxintypemostrelatedtohemolyticuremicsyndrome(HUS) and compriseseveralsubtypeswhichdifferintheircitotoxicity (Perssonetal.,2007). Stx2gisoneofthosesubtypesthatwere studied by GranoblesVelandiaetal.(2012) who foundseveral differencesamong stx2g-positivestrains.Thestrainswiththe highestcytotoxictitershowedhigherlevelsof stx2-phages and toxinproductionbyEIA,whiletheoppositeoccuredforstrains that previouslyshowedlowcytotoxictiters,confirmingthatin stx2g-positivestrainsStxproductionisphageregulated. Other typicalvirulencefactorisintimin,whichisrequiredfor intimatebacterialadhesiontoepithelialcellsinducingachar- acteristiclesiondefinedas?attachingandeffacing?(A/E).Itis encodedby eae gene thatpresentsheterogeneityintheir3 end and involvedinbindingtotheenterocytes(Guthetal.,2010). Additionalvirulence-associatedmarkersareaplasmid-encoded enterohemolysinand,instrainslacking eae, anautoagglutinating adhesin (Saa)whichcouldbeinvolvedintheadhesionofstrains (Patonetal.,2001). Strainslaking eae arenamedasLEE-negative STEC. Steyertetal.(2012) demonstratethattheoverallgenome content,phagelocation,andcombinationofpotentialvirulence factorsarevariableinthisstrainsgroup. STEC arezoonoticpathogensthatcausethevascularendothe- lial damageobservedinpatientswithhemorrhagiccolitis(HC) and HUS.HUSischaracterizedbyacuterenalfailure,thrombocy- topenia,andmicroangiopathichemolyticanemiaandisapoten- tially fatalcauseofacuterenalfailureinchildren(Etcheverríaand Padola,2013). HUStherehasnottreatmentanduseofantimicro- bial agentsisassociatedwithanincreasedriskofseveresequelae such asHUS.Referredtothis, Rahal etal.(2012) dicussed novel modalities andregimenofantimicrobialagentadministration in anattemptatdecreasingtheirassociationwithaggravating infection outcomes. Cattle arethemainreservoirofSTECandshedthebacteria throughtheirfecesspreadingthesepathogensamongcattleherds and theenvironment. NguyenandSperandio(2012) reviewabout the factorsandmechanismutilizedbyO157:H7STECforitssur- vivalthroughtheacidicenvironmentofthedistalstomachandfor its colonizationintherecto-analjunction. Fernándezetal.(2013) characterizedtwomostprevalentserotypesinargentiniancat- tle demonstratingthepotentialpathogenicofthisstrains. Blanco Crivellietal.(2012) informedthatsynanthropicspeciescould playroleinthetransmissibilityoftheagentthusbeingariskto the susceptiblepopulation. Food,water,milk,andpersontopersoncontactcommonly participateintransmission,althoughthereisagrowingconcern about somesporadiccasesandoutbreaksattributabletodirect contactwiththeanimalenvironment(Duffy, 2003). Brusaetal. (2013) reporttheprevalenceofSTECO157andnon-O157in commercialgroundbeefandambientsamples,includingmeat table, knife,meatmincingmachine,andmanipulatorhandssug- gesting cross-contaminationbetweenmeatandtheenvironment. One methodforreducingSTECinfoodcouldbetheuseof phages. Aboutthis, Tomatetal.(2013) informtheisolationof phages highlyspecificforvirotypesof E. coli that couldbeuseful in reducingSTECinmeatproducts. InordertodiagnoseSTEC(O157andnon-O157)several methods havebeenimplementedinthelastyears(Padola,2014). Botkin etal.(2012) investigateamultiplexPCRtodifferenti- ateEPEC,STEC,andEHECstrainsfromotherpathogenic E. coli, FratamicoandBagi(2012) use aGeneDiscsystemtoeval- uateanewPCR-realtimetechnologybasedonsimultaneous detectionofmultipletargets, Quiñones etal.(2012) evaluate a DNAmicroarraytargeted12virulencefactorsimplicatedin producehumandiseasewhile Parmaetal.(2012) developed a sandwichELISAfordeterminationofStxusinganti-Stx2B subunit antibodiesshowingthatcouldbeusedinroutinediag- nosis asarapid,specificandeconomicmethodfordetectionof STEC. TheimplementationofMultiple-locusvariable-number tandem repeatanalysis(MLVA)assubtypingmethodisreview by Bustamanteetal.(2012) who haveadaptedthismethodfor analysis ofnon-O157STECperforminganefficientO157:H7and non-O157 STECsubtyping.