Food Infections of the GIT

Food Poisoning


Beware! > 50% food-related infections come from chicken


GI Defences
Acid (biocide)
Motility
Normal flora (colonisation resistance)
MALT - Peyers patches - sample lumen Ags - seed LProp with T & B cells
B Cells pass through enterocytes & attach to glycoprotein called the secretory piece
Mature secretory IgA = immune exclusion = pathological binding


Organisms


Ingestion of Toxins
Tx + receptor (GIT)

V&D

Central absoption = CNS symptoms

Staph aureus

Vomiting
2-6h
Creams
Cold meats


Bacillus Cereus
V&D
1-10h
Contam rice


Clostridium perfringens
Abdo pain & D
10-20 h
Contam meat stews


Clostridium botulinum
Paralysis
1-3d
Canned foods
Yoghurts


Enterotoxic Organisms
Organism + receptor (GIT)
Secrete Txs

Disrupt enterocyte cell signalling

Loss of Na and H20 from cell

Vibrio cholera

Water-spread

Cholera

Large volume fluid loss

Rapid dehydration

Enterotoxigenic E. coli

Food

Toxin similar to cholera

Not as severe

E. coli O157

Poorly cooked meats
Verotoxin - similar to Shigella

Toxins spread to blood stream

Affects platelets and kidneys
Haemolytic-uraemic sydrome
Enterocyte necrosis = dysentry

Enteroinvasive Bacteria

Invasive organisms = cell necrosis/apoptosis

Txs = binding/penetration/membrane damage/cell death

Erosion and ulceration = dysentry & 'bystander damage'

(acute inflamm = accumulated polymorphs in LPp = releases pore-forming toxins)

Campylobacter jejuni

Chicken

Dysentry

Salmonella enteritidis

Meat & eggs

Diarrhoea

Enteroinvasive E. coli

Dysentry

Shigella sp

Dysentry

F/O

Food/water


Enteroinvasive Viral/Protozoa

Transmitted by water

Watery diarrhoea

Protozoa

Giardia

Cryptosporidia

Entamoeba histolytica (dys)

Virus

RotaV

SRSV

Norwalk

Organisms transmitted by food/water, but without GI symptoms


Listeria

Most foods

*Cheese

Septicaemia

Meningitis

Salmonella typhi

Water-sp

Systemic illness

Some GI symptoms

Polio

Water-sp

Neuro Sys

Hepatitis A

Water

Reaction/Tx

LHA

Prevention

Adequate food preparation

Safe portable water supplies

Good sewage disposal

Vaccination - polio/typhoid