GI Microbiology
Salmonella:
Gram negative rod
1-7 day incubation
Faecal –oral route
Bacteria-mediated endocytosis and intestinal epithelial invasion
Symptoms include: diarrhoea (maybe bloody), fever and cramping
Complications include: bacteriaemia, metastatic infections e.g.
osteomyelitis
Disease is usually self-limiting and treated with supportive I.V fluids
Campylobacter:
Include: C. Jejuni, C. Coli and C. Lari
Gram-negative spiral rod
2-5 day incubation
Invades small/large bowel and causes acute inflammation
Transmission is usually foodborne
Diarrhoea (maybe bloody), abrupt onset of abdominal pain
Complications include: GI haemorrhage, bacteraemia, toxic megacolon,
reactive arthritis,
Disease is usually self-limiting
Shigella:
Shigella sonnei
Gram-negative rod
1-7 day incubation
Low infectious dose (very contagious)
Invasion of colonic mucosal cells leading to inflammatory response
Shiga toxin produced by S. dysenteriae inhibits protein synthesis leading
to cell death and vascular damage.
Symptoms: abdominal cramps, mucoid/bloody diarrhoea, fever and
vomiting
Treatment: fluoroquinolone, amoxicillin
Escherichia coli:
Commensal to highly pathogenic strains
Vero cytotoxin producing E. Coli include enterohaemorrhagic E. coli
(EHEC)
Salmonella:
Gram negative rod
1-7 day incubation
Faecal –oral route
Bacteria-mediated endocytosis and intestinal epithelial invasion
Symptoms include: diarrhoea (maybe bloody), fever and cramping
Complications include: bacteriaemia, metastatic infections e.g.
osteomyelitis
Disease is usually self-limiting and treated with supportive I.V fluids
Campylobacter:
Include: C. Jejuni, C. Coli and C. Lari
Gram-negative spiral rod
2-5 day incubation
Invades small/large bowel and causes acute inflammation
Transmission is usually foodborne
Diarrhoea (maybe bloody), abrupt onset of abdominal pain
Complications include: GI haemorrhage, bacteraemia, toxic megacolon,
reactive arthritis,
Disease is usually self-limiting
Shigella:
Shigella sonnei
Gram-negative rod
1-7 day incubation
Low infectious dose (very contagious)
Invasion of colonic mucosal cells leading to inflammatory response
Shiga toxin produced by S. dysenteriae inhibits protein synthesis leading
to cell death and vascular damage.
Symptoms: abdominal cramps, mucoid/bloody diarrhoea, fever and
vomiting
Treatment: fluoroquinolone, amoxicillin
Escherichia coli:
Commensal to highly pathogenic strains
Vero cytotoxin producing E. Coli include enterohaemorrhagic E. coli
(EHEC)
