Enterobacteriaceae I
(Gram negative rods enteric tract)
Lecture 34
Faculty: Dr. Alvin Fox
1
Key Words
Opportunistic diseases
Diarrhea
Dysentery
Urinary tract infections
Pili
Lactose positive/negative
Enterohemorrhagic E. coli
- Vero toxin (Shiga-like)
- Hemolysin
Enterotoxigenic E. coli
- Heat stable toxin
- Heat labile toxin
Enteropathogenic E. coli
Enteroaggregative E. coli
Enteroinvasive E. coli
Shigella
- Bacillary dysentery
- Shiga toxin
Salmonella enteritidis
Salmonellosis
Salmonella cholerae-suis
Salmonella typhi
- Typhoid
- Vi
Yersinia entercolitica
Vibrio cholerae
Choleragen (cholera toxin)
Campylobacter jejuni
Helicobacter pylori
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Opportunistic diseases
-Enterobacteriaceae
–
–
–
–
septicemia,
pneumonia,
meningitis
urinary tract infections
Citrobacter
Enterobacter
Escherichia
Hafnia
Morganella
Providencia
Serratia
3
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
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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 O157:H7
Flagella
Transmission electron
micrograph
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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”
• 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
Gut lumen
• diarrhea
• vomiting
• nausea
• non-bloody stools (not generally seen as dysentery)
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Enteroaggregative
• Brick-like
bacterial aggregates - 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
[417
]
Caption: Salmonella typhi -
Gram-negative, enteric, rod prokaryote (dividing); causes typhoid fever.
Magnification*: x5,530
Type: SEM
Keywords: 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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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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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
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