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Enterobacteriaceae Part 1

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					ENTEROBACTERIACEAE, VIBRIO, CAMPYLOBACTER AND HELICOBACTER (1)

Faculty: Dr. Alvin Fox

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Key Words
Opportunistic diseases Diarrhea Dysentery Urinary tract infections Lactose positive/negative Enteropathogenic E. coli Enterotoxigenic E. coli Heat stable toxin Heat labile toxin Enteroinvasive E. coli Enterohemorrhagic E. coli Vero toxin (Shiga-like) Hemolysin pili 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

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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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Enterobacteriaceae
• gram negative facultative anaerobic rods – oxidase negative (not 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 and Dysentery

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Caption: E. coli

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Escherichia coli
• E. coli and Shigella – genetically very similar – many similarities in diseases

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Enteropathogenic E. coli
destruction of surface microvilli • fever • diarrhea • vomiting • nausea • non-bloody stools

Gut lumen

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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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Enteroinvasive E. coli (EIEC ) • Dysentery - resembles shigellosis

Gut lumen
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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, 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” • Hemolysins

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

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E. coli fimbriae
Type 1

mannose

P

galactose – glycolipids – glycoproteins
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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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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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