Esherichia coliGram-negative rod Facultative anaerobeNamed for Theodor Escherich German 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 infection Assists in digestion Produces small amounts of vitamins B12 and KColonizes newborns GI tract within hours after birthThere are more than 700 different serotypes of E. coli Distinguished by different surface proteins and polysaccharideswww3.niaid.nih.gov 1Escherichia Escherichia coli coli- large intestine, colon Mammalian large intestine Escherichia blattae blattae. L. n. blatta cockroach Hindgut of cockroach Blatta orientalisBergeys Manual of Systematic Bacteriology2Escherichia 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 1922 Strain K-12 was used for biochemical and genetic studies for many years Metabolism F+ plasmids Bacteriophages Operons Genome sequencing3Many strains O antigen Somatic (on LPS) 171 antigens H antigen Flagella 56 antigens K antigen Capsule and or fimbrial antigen 80 antigensSerotypes Antibody antigen rxnO18ac:H7:K1 18th O antigen1st K antigen 7th H antigen4EPEC Enteropathogenic E. coliETEC Enterotoxigenic E. coliEIEC Enteroinvasive E. coliBergeys Manual of Systematic Bacteriology5Summary of the virulence factors of pathogenic strains of E. coli Fimbriae (Pili) Hemolysins Siderophores Flagella Toxins Endotoxin LPS Capsules K antigens LPS Antigenic variation Drug resistance plasmids Toxin and other virulence plasmidstextbookofbacteriology.netThermolabile toxin (LT)Thermostable toxin (ST)Found alone or togetherBoth are plasmid borne6Pathogenic Agent Urinary Tract Infections Sepsis / neonatal meningitis Enteric / diarrheal diseases7Uropathogenic E. coli UPEC Most common form of extraintestinal E. coli infection Acute symptomatic UTI 12% of all men 10-20% of women 100,000 patients hospitalized for renal infections8Urovirulence FactorsAdherence FimbriaeAerobactin Siderophore Hemolysis a bCapsuleK antigens Resist phagocytosis Resist complement proteinsEndotoxin9Neonatal Meningitis E. coli NMEC Meningitis in an infection of the fluid and membranes that cover the brain and spinal cord Bacteria 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 damage The 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 Fe Endotoxin 1011Enteric / diarrheal diseasesE. coli can adhere to the mucosa of the large intestine12Combinations of the O & H antigens identify the serotypeClinical Microbiology Reviews 1998 11:142-201ETEC Enterotoxigenic E. coliEPEC Enteropathogenic E. coliEHEC Enterohemorrhagic E. coliEAEC Enteroaggregative E. coliEIEC Enteroinvasive E. coli 13Enterotoxigenic E. coli ETEC Adhere to intestinal mucosa by fimbriae Produce enterotoxins Plasmids contain genes for enterotoxins Cause leakage of intestinal epithelial cells Loss of electrolytes & water Attach by fimbriae Cause diarrhea in children & adults Toxins increase intracellular levels of cAMP Causes cell leakage Travelers diarrhea Weanling diarrhea14Enteropathogenic E. coli EPEC Attaching & effacing Effacement of microvilli Adherence between bacterium and epithelial cells Unique histopathology Locus of enterocyte effacementClinical Microbiology Reviews 1998 11:142-20115Clinical Microbiology Reviews 1998 11:142-20116Enteroaggregative E. coli EAEC Adhere to HEp-2 cells Human laryngeal carcinoma cells Bacterial cells autoagglutinate Stick to one another Do not secrete enterotoxinsClinical Microbiology Reviews 1998 11:142-20117Clinical Microbiology Reviews 1998 11:142-20118Enteroinvasive E. coli EIEC Biochemically, genetically, and pathogenetically closely related to Shigella spp. Cause watery diarrhea Not bloody EIEC cells invade intestinal epithelial cells, lyse the phagosomal vacuole, spread through the cytoplasm and infect adjacent cell Shigella does the same thing Plasmid encoding a gene for a K surface antigen Attach and invade mucosal cells19Clinical Microbiology Reviews 1998 11:142-201 20Enterohemorrhagic E. coli EHEC Severe gastrointestinal distress Hemorrhagic colitis Crampy abdominal pain Watery diarrhea Little or no fever Bloody diarrhea New serotype O157:H7 1983 Undercooked hamburgers21E. coli 015:H7Distinguished by serologyCannot be distinguished from all other strains of E. coli using other standard