Faculty: Dr. Alvin Fox

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Enterobacteriaceae I (Gram negative
rods) Lecture 42
Faculty Dr. Alvin Fox
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Key Words
Opportunistic diseases Shigella Diarrhea
- Bacillary dysentery Dysentery - Shiga
toxin Urinary tract infections Salmonella
enteritidis Pili Salmonellosis Lactose
positive/negative Salmonella
cholerae-suis Enterohemorrhagic E. coli
Salmonella typhi - Vero toxin (Shiga-like,
Shiga) - Typhoid - Hemolysin -
Vi Enterotoxigenic E. coli Yersinia
entercolitica - Heat stable toxin Vibrio
cholerae - Heat labile toxin Choleragen
(cholera toxin) Enteropathogenic E. coli
Campylobacter jejuni Enteroaggregative E.
coli Helicobacter pylori Enteroinvasive E.
coli
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Opportunistic diseases -Enterobacteriaceae

• septicemia,
• pneumonia,
• meningitis
• urinary tract infections

Citrobacter Enterobacter Escherichia Hafnia Morgan
ella Providencia Serratia
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Enterobacteriaceae

• gastrointestinal diseases
• Escherichia coli
• Salmonella
• Shigella
• Yersinia entercolitica

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Reiter's syndrome

• Histocompatibility antigen (HLA) B27
• Enterobacteriaceae
• Salmonella
• Shigella
• Yersinia

• Non-Enterobacteriaceae
• Campylobacter
• Chlamydia

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Enterobacteriaceae

• community acquired
• otherwise healthy people
• Klebsiella pneumoniae
• respiratory diseases
• prominent capsule
• urinary tract infection
• fecal contamination
• E. coli
• Proteus
• urease (degrades urea)
• alkaline urine

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E. coli fimbriae
Type 1
mannose
P

• galactose
• glycolipids
• glycoproteins

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Enterobacteriaceae

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

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Feces

• E. coli
• lactose positive
• not usually identified
• lactose positive sp. common, healthy intestine
• Shigella, Salmonella,Yersinia
• lactose negative
• identified

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Enterobacteriaceae

• other sites
• identified biochemically

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Serotypes

• reference laboratory
• antigens
• O (lipopolysaccharide)
• H (flagellar)
• K (capsular)

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Diarrhea (watery feces) and Dysentery (blood in
stools)
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Caption E. coli
Escherichia coli
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Escherichia coli

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

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Enterohemorrhagic E. coli

• Usually O157H7

Flagella
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Transmission meat products or
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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Enterohemorrhagic E. coli

• Vero toxin
• shiga-like toxin
• shiga toxin
• Hemolysins

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Enterotoxigenic E. coli

• diarrhea like cholera
• milder
• travellers diarrhea

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Enterotoxigenic E. coli

• Heat labile toxin
• like choleragen
• Adenyl cyclase activated
• cyclic AMP
• secretion water/ions
• Heat stable toxin
• Guanylate cyclase activated
• cyclic GMP
• uptake water/ions

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Enteropathogenic E. 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 aggregates on cell surfaces
• Mucus biofilm inhibits fluid absorption
• Diarrhea

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Enteroinvasive E. coli (EIEC )

• Dysentery
• - resembles shigellosis

Gut lumen
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Treatment -gastrointestinal disease

• fluid replacement
• antibiotics
• not used usually unless systemic
• e.g. hemolytic-uremia syndrome

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Shigella
Modified from Fig, Dennis Kunkel
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Shigella

• S. flexneri, S. boydii, S. sonnei, S. dysenteriae
• bacillary dysentery
• shigellosis
• bloody feces
• intestinal pain
• pus

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Shigellosis

• within 2-3 days
• epithelial cell damage

Gut lumen
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Shiga toxin

• enterotoxic
• cytotoxic
• inhibits protein synthesis
• lysing 28S rRNA

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Shigellosis

• man only "reservoir"
• mostly young children
• fecal to oral contact
• children to adults
• transmitted by adult food handlers
• unwashed hands

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Treating shigellosis

• manage dehydration
• patients respond to antibiotics
• disease duration diminished

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Salmonella



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                                                                                                                                                                                                                   Caption Salmonella typhi - Gram-negative, enteric, rod prokaryote (dividing) causes typhoid fever.Magnification x5,530Type 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
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Salmonella

• 2000 antigenic "types
• genetically single species
• S. enterica
• disease category
• S. enteritidis
• many serotypes
• S. cholerae-suis
• S. typhi

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Salmonellosis

• S. enteritidis
• the common salmonella infection
• poultry, eggs
• no human reservoir
• Gastroenteritis
• nausea
• vomiting
• non-bloody stool
• self-limiting (2 - 5 days)

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Salmonellosis
Gut lumen
uncomplicated cases (the vast majority)
antibiotic therapy not useful
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S. cholerae-suis

• much less common
• septicemia
• antibiotic therapy essential