Class- Esherichia Coli

Esherichia coliAlternative NamesTraveler's diarrhea - E. coli; Food poisoning - E. coli; E. coli diarrhea; Hamburger disease

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NEWS & FEATURES

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*Esherichia coliGram-negative rod (Bacilli)Facultative anaerobe

Named after Theodor EscherichGerman physician (ca. 1885)Demonstrated that particular strains were responsible for infant diarrhea and gastroenteritis

Normal flora of the mouth and intestine Protects the intestinal tract from bacterial infectionAssists in digestionProduces small amounts of vitamins B12 and K

Colonizes newborns GI tract within hours after birth

There are more than 700 different serotypes of E. coliDistinguished by different surface proteins and polysaccharides

www3.niaid.nih.gov

*Escherichia Escherichia colicoli- large intestine, colonMammalian large intestineEscherichia blattaeblattae. L. n. blatta cockroach Hindgut of cockroach Blatta orientalisBergeys Manual of Systematic Bacteriology

*Escherichia coli K-12 strain The original E. coli strain K-12 was obtained from a stool sample of a diphtheria patient in Palo Alto, CA in 1922Strain K-12 was used for biochemical and genetic studies for many years MetabolismF+ plasmidsBacteriophagesOperonsGenome sequencing

*Many strainsO antigenSomatic (on LPS)171 antigensH antigenFlagella56 antigensK antigenCapsule and or fimbrial antigen80 antigens

SerotypesAntibody antigen rxn

O18ac:H7:K1

18th O antigen1st K antigen7th H antigen

*EPECEnteropathogenic E. coliETECEnterotoxigenic E. coliEIECEnteroinvasive E. coliBergeys Manual of Systematic Bacteriology

*Summary of the virulence factors of pathogenic strains of E. coli Fimbriae (Pili) Hemolysins Siderophores FlagellaToxins Endotoxin LPSCapsules K antigens LPSAntigenic variationDrug resistance plasmids Toxin and other virulence plasmids

textbookofbacteriology.netThermolabile toxin (LT)

Thermostable toxin (ST)

Found alone or together

Both are plasmid borne

*Pathogenic AgentUrinary Tract InfectionsSepsis / neonatal meningitis Enteric / diarrheal diseases

*Uropathogenic E. coli UPEC Most common form of extraintestinal E. coli infectionAcute symptomatic UTI12% of all men10-20% of women100,000 patients hospitalized for renal infections

Symptoms

*E. colienteritis is swelling (inflammation) of the small intestine fromEscherichia coli(E. coli) bacteria. It is the most common cause of travelers' diarrhea. Also the 3rd leading cause of infant mortality.

Symptoms occur whenE. colibacteria enter the intestine. The time between being infected and developing symptoms is usually 24to 72 hours. The most common symptom is sudden, severe diarrhea that is often bloody.Other symptoms may include:FeverGasLoss of appetiteStomach crampingVomiting (rare)Symptoms of a rare but severeE. coliinfection include:Bruises that happen easilyPale skinRed or bloody urineReduced amount of urine

Exams and Tests

*A stool culture can be done to check for disease-causingE.coli.

Toxicity testing by different in vivo, in vitro and cell culture assay.

TREATMENT*Most of the time, you will recover from the most common types ofE. coli infection within a couple of days. The goal of treatment is to make you feel better and avoid dehydration. Getting enough fluids and learning what to eat will help keep you or your child comfortable. *Avoid anti-diuretic (for toxin removal, Antibiotic - complications You need to:Manage the diarrheaControl nausea and vomitingGet plenty of restYou can drink oral rehydration mixtures to replace fluids and minerals lost through vomiting and diarrhea. Oral rehydration powder can be purchased from a pharmacy. Be sure to mix the powder in safe water.You can make your own mixture by dissolving teaspoonful each salt and baking soda and 4 table spoonsful sugar in 4 cups (1 liter) water.If you have diarrhea or vomiting and cannot drink or keep enough fluids in your body, you may need fluids given through a vein (IV).You will need to go to your health care provider's office or the emergency room.If you take diuretics (water pills), talk to your health care provider. You may need to stop taking the diuretic while you have diarrhea. Never stop or change medications without first talking to your health care provider. You can buy medicines at the drugstore that can help stop or slow diarrhea. Do not use these medicines without talking to your health care provider if you have bloody diarrhea or a fever. Do not give these medicines to children.

*Urovirulence FactorsAdherenceFimbriaeAerobactinSiderophore HemolysisabCapsuleK antigensResist phagocytosisResist complement proteinsEndotoxin

*Neonatal Meningitis E. coli NMEC

Meningitis in an infection of the fluid and membranes that cover the brain and spinal cordBacteria Viruses Fungi

E. coli incites between 1/4 and 1/3 of meningitis cases in newborns Less than 2% of cases of meningitis at all other ages Approximately 1 out of 5 newborns with E. coli meningitis dies Survivors frequently sustain permanent brain damageThe majority of cases occur in premature babies

K-1 80% of NMEC E. coli strains produce K-1 capsular antigens K1 capsular polysaccharide O18ac:H7:K1 Inhibits phagocytosis

Siderophore production Sequesters FeEndotoxin

*Enteric / diarrheal diseases

E. coli can adhere to the mucosa of the large intestine

*Combinations of the O & H antigens identify the serotypeClinical Microbiology Reviews 1998 11:142-201ETECEnterotoxigenic E. coliEPECEnteropathogenic E. coliEHECEnterohemorrhagic E. coliEAECEnteroaggregative E. coliEIECEnteroinvasive E. coli

*Enterotoxigenic E. coli ETECAdhere to intestinal mucosa by fimbriaeProduce enterotoxinsPlasmids contain genes for enterotoxinsCause leakage of intestinal epithelial cellsLoss of electrolytes & waterAttach by fimbriaeCause diarrhea in children & adultsToxins increase intracellular levels of cAMPCauses cell leakageTravelers diarrheaWeanling diarrhea

*Enteropathogenic E. coli EPECAttaching & effacing Effacement of microvilli Adherence between bacterium and epithelial cellsUnique histopathologyLocus of enterocyte effacementClinical Microbiology Reviews 1998 11:142-201

*Clinical Microbiology Reviews 1998 11:142-201

*Enteroaggregative E. coli EAECAdhere to HEp-2 cellsHuman laryngeal carcinoma cellsBacterial cells autoagglutinateStick to one anotherDo not secrete enterotoxins

Clinical Microbiology Reviews 1998 11:142-201

*Enteroinvasive E. coli EIECBiochemically, genetically, and pathogenetically closely related to Shigella spp.Cause watery diarrheaNot bloodyEIEC cells invade intestinal epithelial cells, lyse the phagosomal vacuole, spread through the cytoplasm and infect adjacent cellShigella does the same thingPlasmid encoding a gene for a K surface antigenAttach and invade mucosal cells

*Enterohemorrhagic E. coli EHECSevere gastrointestinal distressHemorrhagic colitisCrampy abdominal painWatery diarrheaLittle or no feverBloody diarrheaNew serotype O157:H71983Undercooked hamburgers

*E. coli 015:H7Distinguished by serologyCannot be distinguished from all other strains of E. coli using other standard microbiological tests

*E. coli 015:H7157th somatic O antigen7th flagellar H antigenHemorrhagic colitisAbdominal cramps, blood stools, with minor or no feverPost diarrheal hemolytic ureamic syndromeAcute renal injuryThrombocytopeniaAn abnormal decrease in the number of platelets in circulatory blood. Microangiopathic hemolytic anemiaThe fragmentation of red blood cells because of narrowing or obstruction of small blood vessels.Enterohemorrhagic E. coliEHECAmong the most dangerous enteric pathogensThe Lancet 1998 352:1207-1212

*ReservoirHealthy cattle are the major reservoir for human infectionDeer, sheep, goats, horses, dogs, birds and fliesBacterial cells can survive in manure and water troughsInfection is more common during the summer in both the northern and southern hemisphere

*Transmitted via foodGround beefRaw milkLamb meatVenison jerkySalami and other fermented dried meat productsLettuce, spinach, alfalfa sproutsUnpasteurized apple ciderTransmitted via waterDrinking and swimming in unchlorinated waterDirect person to person contactDiaper changingImproper sanitationDay care & chronic adult care facilities

*Clinical FeaturesAverage interval between exposure & illness is 3 days

Most patients recover within 7 days

70% of patients report bloody stools

30-60% of patients report vomiting

Approx 5% of patients develop HUS (Hemolytic Uremic Syndrome)

The Lancet 1998 352:1207-1212SequelaeA condition following as a consequence of a disease. ProteinuriaExcess protein in the urine.

*IdentificationMacConkey agar (SMAC)Does not ferment sorbitol rapidlyForms colorless colonies on sorbitol containing MacConkey agarSerologyColorless colonies on SMAC are screened for the 0157 antigenMolecular In vivo In vitoCell culture

*Shiga Like Toxins (SLT)ExotoxinVery similar to toxin produced by Shigella dysenteriaeInhibits protein synthesis in host cellA subunit inactivates the 60S ribosomal subunitShiga toxin producing E. coli (STEC)VerotoxinsMost OH157 strains produce Shiga toxin 225% produce Shiga toxin 1 Identical to Shigella toxinA B exotoxinA subunit exists on a temperate bacteriophage

*Cells leak Na+, Cl-, K+, HCO3- and waterWatery diarrheaCrampsNauseaVomitingBloody stool

*Virulence FactorsVirulence plasmid (pO157)Encodes a hemolysinO157 strains can use iron from blood released into the intestineLocus of enterocyte effacementAdhesion proteins

*Non O157 Shiga Toxin Producing E. coliSeveral other serotypes of E. coli produce Shiga toxinsO111:nonmotileO26:H11O132:H2Incite diarrhea, hemorrhagic colitis & HUSLabs generally not prepared to identify these strains Many times go undetected

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Class- Esherichia Coli