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Faculty: Dr. Alvin Fox

Enterobacteriaceae Enterobacteriaceae I I (Gram negative rods enteric tract)(Gram negative rods enteric tract)

Lecture 34Lecture 34

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Key WordsOpportunistic diseases Opportunistic diseases ShigellaShigella DiarrheaDiarrhea - Bacillary dysentery - Bacillary dysenteryDysentery Dysentery - Shiga toxin - Shiga toxin Urinary tract infections Urinary tract infections Salmonella enteritidisSalmonella enteritidis Pili Pili Salmonellosis SalmonellosisLactose positive/negativeLactose positive/negative Salmonella cholerae-suis Salmonella cholerae-suisEnterohemorrhagic Enterohemorrhagic E. coliE. coli Salmonella typhi Salmonella typhi - Vero toxin (Shiga-like)- Vero toxin (Shiga-like) - Typhoid - Typhoid- Hemolysin- Hemolysin - Vi - ViEnterotoxigenic Enterotoxigenic E. coliE. coli Yersinia entercolitica Yersinia entercolitica - Heat stable toxin - Heat stable toxin Vibrio cholerae Vibrio cholerae- Heat labile toxin - Heat labile toxin Choleragen (cholera toxin) Choleragen (cholera toxin)Enteropathogenic Enteropathogenic E. coliE. coli Campylobacter jejuni Campylobacter jejuniEnteroaggregative Enteroaggregative E. coliE. coli Helicobacter pylori Helicobacter pylori Enteroinvasive Enteroinvasive E. coli E. coli

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– septicemia, septicemia, – pneumonia, pneumonia, – meningitismeningitis– urinary tract infectionsurinary tract infections

Citrobacter EnterobacterEscherichiaHafniaMorganellaProvidenciaSerratia

Opportunistic diseases Opportunistic diseases --EnterobacteriaceaeEnterobacteriaceae

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EnterobacteriaceaeEnterobacteriaceae

• gastrointestinal diseasesgastrointestinal diseases– Escherichia coliEscherichia coli – SalmonellaSalmonella– ShigellaShigella – Yersinia entercoliticaYersinia entercolitica

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• Histocompatibility antigen (HLA) B27Histocompatibility antigen (HLA) B27

– Enterobacteriaceae*Salmonella*Shigella*Yersinia

– Non-Non-EnterobacteriaceaeEnterobacteriaceae*CampylobacterCampylobacter*ChlamydiaChlamydia

Reiter's syndromeReiter's syndrome

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• community acquired • otherwise healthy people

– Klebsiella pneumoniae * respiratory diseases* prominent capsule

–urinary tract infection–fecal contamination *E. coli*Proteus

– urease (degrades urea)urease (degrades urea)– alkaline urinealkaline urine

EnterobacteriaceaeEnterobacteriaceae

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E. coliE. coli fimbriae fimbriae

mannosemannose

Type 1 Type 1

galactose galactose – glycolipids glycolipids – glycoproteins glycoproteins

P P

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EnterobacteriaceaeEnterobacteriaceae

• gram negative facultative anaerobic rodsgram negative facultative anaerobic rods– – oxidase negative (no cytochrome oxidase)oxidase negative (no cytochrome oxidase)

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• E. coli – lactose positive – not usually identified– lactose positive sp. common, healthy intestine

• Shigella, Salmonella,Yersinia– lactose negative– identified

FecesFeces

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• other sitesother sites– identified biochemicallyidentified biochemically

EnterobacteriaceaeEnterobacteriaceae

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SerotypesSerotypes

• reference laboratoryreference laboratory– antigens antigens

• O (lipopolysaccharide) O (lipopolysaccharide) • H (flagellar) H (flagellar) • K (capsular) K (capsular)

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Diarrhea Diarrhea (watery feces) (watery feces) and Dysentery and Dysentery (blood in stools)(blood in stools)

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Caption: E. coli

Escherichia coliEscherichia coli

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• E. coli and Shigella– genetically very similar– separated for historical reasons – overlap in pathogenesis

Escherichia coliEscherichia coli

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Enterohemorrhagic Enterohemorrhagic E. coliE. coli

• Usually O157:H7

Transmission electron micrograph

Flagella

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Transmission – meat products or Transmission – meat products or sewage-contaminated vegetables sewage-contaminated vegetables

• Hemorrhagic – Bloody dysentery – copious diarrhea– few leukocytes – afebrile

• hemolytic-uremic syndrome – hemolytic anemia– thrombocytopenia (low platelets)– kidney failure

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• Vero toxin Vero toxin – “ “shiga-like toxin”shiga-like toxin”

• HemolysinsHemolysins

Enterohemorrhagic Enterohemorrhagic E. coliE. coli

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Enterotoxigenic Enterotoxigenic E. coliE. coli

• diarrhea like cholera diarrhea like cholera • milder milder • travellers diarrheatravellers diarrhea

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Enterotoxigenic Enterotoxigenic E. coliE. coli • Heat labile toxinHeat labile toxin

– like choleragenlike choleragen

– Adenyl cyclase activated Adenyl cyclase activated

– cyclic AMP cyclic AMP

– secretion water/ionssecretion water/ions

• Heat stable toxinHeat stable toxin

– Guanylate cyclase activated Guanylate cyclase activated

– cyclic GMPcyclic GMP

– uptake water/ionsuptake water/ions

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Enteropathogenic Enteropathogenic E. coliE. coli

destruction of surface microvilli

• fever• diarrhea• vomiting • nausea • non-bloody stools (not generally seen as dysentery)

Gut lumen

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Enteroaggregative

• Brick-like bacterial aggregates - cell surfaces

• Mucus biofilm inhibits fluid absorption

• Diarrhea

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• Dysentery- resembles shigellosis

Enteroinvasive Enteroinvasive E. coliE. coli (EIEC ) (EIEC )

Gut lumen

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Treatment -gastrointestinal Treatment -gastrointestinal diseasedisease

• fluid replacementfluid replacement

• antibioticsantibiotics

– not used usually unless systemic not used usually unless systemic

–e.g. hemolytic-uremia syndromee.g. hemolytic-uremia syndrome

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Shigella Shigella

Modified from Fig, Dennis Kunkel

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ShigellaShigella

• S. flexneri, S. boydii, S. sonnei, S. S. flexneri, S. boydii, S. sonnei, S. dysenteriaedysenteriae– bacillary dysenterybacillary dysentery– shigellosisshigellosis

• bloody fecesbloody feces• intestinal painintestinal pain• puspus

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ShigellosisShigellosis

• within 2-3 dayswithin 2-3 days– epithelial cell damageepithelial cell damage

Gut lumen

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Shiga toxinShiga toxin• enterotoxicenterotoxic

• cytotoxiccytotoxic

• inhibits protein synthesisinhibits protein synthesis– lysing 28S rRNA

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ShigellosisShigellosis

• man only "reservoir"man only "reservoir"

• mostly young children mostly young children

– fecal to oral contactfecal to oral contact

– children to adultschildren to adults

• transmitted by adult food handlerstransmitted by adult food handlers

– unwashed handsunwashed hands

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Treating shigellosisTreating shigellosis

• manage dehydration

• patients respond to antibiotics– disease duration diminished

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[417]

                                                                                                                                                                                                                   Caption: Salmonella typhi - Gram-negative,

enteric, rod prokaryote (dividing); causes typhoid fever.Magnification*: x5,530

Type: SEMKeywords: 96430B.TIF bacilli bacillus bacteria bacterial pathogen bacterium division Gram-negative human disease infection prokaryote rod Salmonella

typhi typhoid fever enteric bacterial pathogen intestinal tract infection SEM |

Salmonella

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SalmonellaSalmonella• 2000 antigenic "types”2000 antigenic "types”• genetically single speciesgenetically single species

– S. entericaS. enterica

• disease categorydisease category – S. enteritidisS. enteritidis

– many serotypesmany serotypes

– S. cholerae-suisS. cholerae-suis

– S. typhiS. typhi

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SalmonellosisSalmonellosis

• S. enteritidisS. enteritidis– the common salmonella infectionthe common salmonella infection– poultry, eggspoultry, eggs– no human reservoirno human reservoir

– Gastroenteritis Gastroenteritis • nausea nausea

• vomiting vomiting

• non-bloody stoolnon-bloody stool

• self-limiting (2 - 5 days)self-limiting (2 - 5 days)

Control of salmonellosis

• Monitoring of food in the US is limited– microbiology is difficult

• Regulation is not optimal

• Chickens are not vaccinated in US– UK, salmonellosis largely erradicated

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SalmonellosisSalmonellosis

uncomplicated cases (the vast majority) antibiotic therapy not useful

Gut lumen

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S. cholerae-suisS. cholerae-suis

• much less common

• septicemia

• antibiotic therapy essential