Transcript There are two types of food poisoning

FOOD POISONING
&
Bacterial causes of acute
infectious gastroenteritis
What is food poisoning??:
• any illness resulting from the consumption of food
• There are two types of food poisoning:
1) Food infection
refers to the presence of bacteria or other microbes which infect the
body after consumption.
2) Food intoxication
refers to the ingestion of toxins contained within the food, including
bacterially produced exotoxins, which can happen even when the
microbe that produced the toxin is no longer present or able to
cause infection
Food poisoning
Food poisoning occurs after:
1- Ingestion of food contaminated with
chemical toxin
2- Ingestion of food contaminated with
bacterial pathogens and/or their toxins
Bacterial food poisoning
1) food poisoning caused by bacterial toxins
• Staphylococcus Aureus
• Bacillus Cerus
• Clostridium perfringens
• Clostridium botulinum
2) food poisoning caused by bacterial infection
• Salmonella
• E. Coli
• Shigella spp.
• Camplobacter jejuni
• Listeria
• Yersinia enterocolitis
Staphylococcus
Aureus
Found in human
nose and throat
(also skin)
Salmonella
Found in animals,
raw poultry and
birds
Bacillus Cereus
Found in soil,
vegetation,
cereals and
spices
Clostridium
Perfingens
Found in animals
and birds
Clostridium
Botulinum
Found in the soil
and associated
with vegetables
and meats
STAPHYLOCOCCAL FOOD POISONING
• Staph. aureus is a common commensal of the anterior
nares.
• transmission takes place via the hands of food handlers to
foodstuffs such as dairy products, including cheese, and
cooked meats.
• Inappropriate storage of these foods allows growth of
the staph. and production of one or more heat-stable
enterotoxins. (Toxin may survive boiling for up to 30
minutes. )
• Incubation period 1-6 hrs
STAPHYLOCOCCAL FOOD POISONING
Clinical features:
• Nausea and profuse vomiting develop within 16 hours.
• Diarrhoea may not be marked.
• Most cases settle rapidly but severe
dehydration and rare fatalities have occurred
due to acute fluid loss and shock.
Management:
• Antiemetics and appropriate fluid
replacement are the mainstays of treatment.
• Suspect food should be cultured for
staphylococci and demonstration of toxin
production.
BACILLUS CEREUS
• Ingestion of the heat-stable exotoxins of B.
cereus causes rapid onset of vomiting and
diarrhoea within hours of food consumption,
which resolves within 24 hours.
• sources of infections : Fried rice or freshly
made vanilla sauces
• If viable bacteria are ingested the toxin
formation takes place within the gut lumen
BACILLUS CEREUS
Clinical features
• the incubation period is longer (12-24 hours)
• Vomiting, watery diarrhoea and abdominal
cramps are the predominant symptoms.
• The disease is self-limiting but can be quite
severe.
• Management :
Rapid and judicious fluid replacement and
appropriate notification of the public health
CLOSTRIDIUM PERFRINGENS
• Spores of Cl. perfringens are widespread in
the guts of large animals and in soil.
• If contaminated meat products are
incompletely cooked and stored in anaerobic
conditions, Cl. perfringens spores germinate
and viable organisms multiply to give large
numbers.
• Subsequent reheating of the food causes
heat-shock sporulation of the organisms
during which they prduces an enterotoxin.
CLOSTRIDIUM PERFRINGENS
• Symptoms - Abdominal pain, diarrhoea, occasional
vomiting and fever.
• Duration is usually 12 to 48 hours.
• Clostridial enterotoxins are potent and most people
who ingest them will be symptomatic.
• Point source' outbreaks, in which nomber of cases all
become symptomatic following ingestion, classically
occur after school or canteen lunches where meat
stews are served.
What is botulism food poisoning
•
Botulism is a disease caused by the bacterium
scientifically known as Clostridium botulinum.
•
Botulism food poisoning occurs when a toxin produced
by the bacteria is consumed in improperly preserved
foods. The disease is caused by a potent neurotoxin
produced by the bacteria.
•
It manifests as abdominal cramping, double or blurred
vision, difficulty breathing, muscle weakness, and other
serious symptoms.
•
Botulism is not spread from person to person.
CAMPYLOBACTER JEJUNI
• This infection is essentially a zoonosis.
• the organisms originating in the gut of cattle and poultry.
• The most common source of the infection is meat, such
as chicken, or contaminated milk products.
• The leading cause of enteritis worldwide
• Very low infective does required to cause infection
• The incubation period is 2-5 days.
• Colicky abdominal pain, which may be quite severe and
mimic surgical pathology, occurs with nausea, vomiting
and significant diarrhoea, frequently containing blood.
CAMPYLOBACTER JEJUNI
• The majority of Campylobacter infections affect fit
young adults
• Infection is self-limiting, 5-8 days, then individuals become
carriers for up to 4 weeks
• About 10-20% will have prolonged symptomatology,
occasionally meriting treatment with antibiotics such as
ciprofloxacin 500 mg twice daijy for 5- 7 days .
• Approximately 1% of cases will develop bacteraemia
and possible distant foci of infection.
•
Post infection complicatin could lead to Guillain-Barre’
syndrome ( acute post-infective polyneuritis)
Salmonella spp.(non-typhohdal) infection
• Salmonella serotypes (other than S. typhi and
S. paratyphi ), are subdivided into five distinct
subgroups which produce gastroenteritis.
• Second leading cause of enteritis worldwide
• Two serotypes are most important world-wide:
S. enteritidis
S. typhimurium .
• Infected personnel become carriers
• Infection requires low does (estimated 200 cells)
• Transmission is by contaminated water or food,
particularly poultry, egg products and related
fast foods.
Salmonella infection
• The incubation period of Salmonella gastroenteritis is
12-72 hours and
• the predominant feature is diarrhoea & vomiting .
and blood is quite frequently noted in the stool.
• Reactive (post-infective) arthritis occurs in
approximately 2% of cases.
• Rieter,s disease (arthritis, conjunctivi & urethritis)
may occures
• Antibiotics are not indicated for uncomplicated
Salmonella gastroenteritis.
• However, evidence of bacteraemia is a clear
indication for antibiotic therapy
MOST COMMON CAUSES OF
TRAVELLERS' DIARRHOEA
•
•
•
•
•
Enterotoxigenic E. coli (ETEC)
Shigella spp.
Campylobacter jejuni
Salmonella spp.
Non-cholera Vibrio spp.
ESCHERICHIA COLI
• Many serotypes of this major member of the
Enterobacteriaceae may be present in the human gut at any
given time.
• Types of E. Coli
Enterotoxigenic E. coli (ETEC)
Entero invasive E. Coli (EIEC)
Enteropathogenic E. coli (EPEC)
Entero-aggregative E. coli (EAEC):
Enterohaemorrhagic E. coli (EHEC):
• Travel to unfamiliar areas of the world allows contact with
previously unknown strains of endemic E. coli and the
development of travellers' diarrhoea.
Enterotoxigenic E. coli (ETEC) :
• These cause most cases of travellers' diarrhoea in
developing countries.
• The organisms produce either
heat-labile enterotoxin or
heat-stable enterotoxin,
causing marked secretory diarrhoea and vomiting
after 1-2 days' incubation.
• The illness is usually mild and self-limiting after 3-4
days.
• Antibiotics, such as ciprofloxacin, have been used to
limit the duration of symptoms but are of
questionable value.
Entero-invasive E. coli (EIEC):
•
This illness is very similar to Shigella dysentery and
is caused by invasion and destruction of colonic
mucosal cells.
• No enterotoxin is produced.
• Acute watery diarrhoea, abdominal cramps and some
scanty blood-staining of the stool are common.
• The symptoms are rarely severe and are usually selflimiting.
Enteropathogenic E. coli (EPEC):
• These are very important in infant diarrhoea.
• Ability to attach to the gut mucosa is the basis of
their pathogenicity.
• This causes destruction of microvilli and disruption of
normal absorptive capacity.
•
The symptoms vary from mild non-bloody diarrhoea
to quite severe illness.
• Bacteraemia/septicaemia is virtually unheard of.
•
These strains have the genetic codes for adherence
to the mucosa but also produce a locally active
enterotoxin.
• They have been associated with prolonged diarrhoea.
Enterohaemorrhagic E. coli (EHEC):
• E. coli O157:H7 is perhaps the best known
verocytotoxigenic E. coli (VTEC).
• The reservoir of infection is in the gut of herbivores.
Sources of infection
• contaminated water which is used to irrigate
vegetable crops
• contaminated milk
• meat products (especially hamburgers which have
been incompletely cooked)
• lettuce and apple juice
• Enterohaemorrhagic E. coli (EHEC):
• The incubation period is between 1 and 7 days.
• Initial watery diarrhoea becomes frankly and uniformly
blood-stained in 70% of cases and is associated with
severe and often constant abdominal pain.
• There is little systemic upset, vomiting or fever.
•
Enterotoxins, if produced, have both a local effect on
the bowel and a distant effect on particular body
tissues such as glomerular apparatus, heart and brain.
• The potentially life-threatening haemolytic uraemic
syndrome (HUS) occurs in 10-15% of sufferers from
this infection, arising 5-7 days after the onset of
symptoms.
• It is most likely at the extremes of age, is heralded
by a high peripheral leucocyte count and may be
induced, particularly in children, by antibiotic therapy.
• HUS is treated by
dialysis
plasma exchange.
ANTIBIOTIC-ASSOCIATED DIARRHOEA
(CL. DIFFICILE INFECTION)
• A history of any antibiotic therapy in the 6 weeks
prior to the onset of diarrhoea can be related to the
finding of Cl. difficile or its toxins in the stool.
•
This is a potent cause of diarrhoea and can produce
life-threatening pseudomembranous colitis.
• This diagnosis is by
stool ex. For cl. Difficile cytotoxin
stool culture for cl. Difficile
• Treatment
metronidazole 400 mg 8-hourly for 10 days.
vancomycin may be used (125 mg orally6-hourly for 1
week).
•
YERSINIA ENTEROCOLITICA
• This organism, commonly found in pork, causes
mild to moderate gastroenteritis
mesenteric adenitis
• incubation period of 3-7 days.
• It predominantly causes disease in children but adults
may also be affected.
BACILLARY DYSENTERY (SHIGELLOSIS)
• Shigellae are Gram-negative rods, closely related to
E. coli, that invade the colonic mucosa.
• There are four main groups:
Sh. dysenteriae,
Sh. flexneri,
Sh. boydii
Sh. sonnei.
• In the tropics bacillary dysentery is usually caused by
Sh. Flexneri.
• The organism only infects humans and its spread is
facilitated by its low infecting dose of around 10
organisms.
Epidemiology of shigellosis:
• Spread may occur via contaminated food or flies, but
transmission by unwashed hands after defaecation is
by far the most important factor.
• Outbreaks occur in mental hospitals, residential
schools and other closed institutions,
• dysentery is a constant accompaniment of wars and
natural catastrophes which lead to crowding and poor
sanitation.
Clinical features
• Disease severity varies from
Sh. sonnei infections is mild that may escape
detection
Sh. Flexneri is more severe infections,
Sh. dysenteriae may be fulminating and cause death
within 48 hours.
•
In a moderately severe illness, the patient complains
of diarrhoea, colicky abdominal pain and tenesmus.
Stools are small, and after a few evacuations contain
blood and purulent exudate with little faecal material.
• Fever, dehydration and weakness with tenderness
over the colon occur.
Management
• Oral rehydration therapy or, if diarrhoea is severe,
intravenous replacement of water and electrolyte loss
will be necessary.
•
Antibiotic therapy with ciprofloxacin 500 mg 12hourly for 3 days is effective in known shigellosis and
appropriate in epidemics.
• The use of antidiarrhoeal medication should be
avoided in all but the mildest cases.
NON-INFECTIOUS CAUSES OF
FOOD POISONING
Plant toxins
• Legumes and beans produce oxidants which are toxic to
people with glucose-6-phosphate dehydrogenase
(G6PD) deficiency Consumption produces headache,
nausea and fever progressing to severe haemolysis,
haemoglobinuria and jaundice (favism).
• Many fungal species induce a combination of
gastroenteritis and cholinergic symptoms of blurred
vision, salivation, sweating and diarrhoea.
• Amanita phalloides (death head mushroom) causes
acute abdominal cramps and diarrhoea followed by
hepatorenal failure, often fatal
Chemical toxins
• Paralytic shellfish toxin
Consumption produces gastrointestinal symptoms within
30 minutes, followed by respiratory paralysis.
• Warm-water coral reef fish
Consumption produces gastrointestinal symptoms 1-6
hours later with associated paraesthesiae of the lips and
extremities, distorted temperature sensation, myalgia
and progressive flaccid paralysis.
. The gastrointestinal symptoms resolve rapidly but the
neuropathic features may persist for months.
Chemical toxins
• Scombrotoxic fish poisoning
Consumption produces symptoms within minutes with
flushing, burning, sweating, urticaria, pruritus, headache,
colic, nausea and vomiting, diarrhoea, bronchospasm
and hypotension.
Management is with salbutamol and antihistamines.
• Thallium and cadmium can cause acute vomiting and
diarrhoea resembling staphylococcal enterotoxin
poisoning.
References:
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