Food Poisoning

Presented by: Saundarya DeepakJSS MEDICAL COLLEGE,MYSORE

Food Poisoning

Food poisoning is defined as food borne illness that is

acquired through ingestion of food contaminated with

pathogenic microorganisms,which can be either

bacterial and non bacterial toxins.

OR Food poisoning is the acute manifestation of diarrhea

or vomiting caused by toxins produced by microorganisms.

Epidemiology

• An estimated 600 million – almost 1 in 10 people in the world – fall ill after eating contaminated food .

• 420 000 die every year, resulting in the loss of 33 million healthy life.

• Children under 5 years of age constitute 40% of the food borne disease, with 125 000 deaths every year.

Classification of food borne diseases

Food borne diseases are classified into:1. Food borne infections and2. Food borne intoxications

1. Food borne infections : Infective doses of microorganisms are

ingested with food .

2. Food borne intoxications: Preformed toxin ingested with food.

Food borne infections

Food borne infections• Food borne infections are caused by the entry of

pathogenic microorganisms contaminating food into the GIT.

• long incubation periods.

• Characterized by fever.

• Either be fungal, bacterial, viral or parasitic.

Food Borne Infections types

BACTERIAL• Salmonellosis• Campylobacteriosis• Escherichia coli infection• Shigellosis• Cholera • Vibrio parahemolyticus• Vibrio vulnificus• Yersiniosis

Fungal• Aspergillus species

PARASITIC• Cryptosporodiosis• Giardiasis

VIRAL• Hepatitis A• Norwalk like virus

Salmonellosis • Food poisoning caused by consumption of food

contaminated with Non typhoidal  Salmonella. Salmonella typhimurium Salmonella newport. Salmonella enteritidis Salmonella softenburg

Salmonella choleraisuis Salmonella infantis

• A heavy dose up to 10,000 -1,000,000 bacilli per gram of food is required to cause infection.

• Incubation period is 12 -24 hours.

Transmission 1. Consumption of contaminated food from carriers,

from human excreta.

2. Transferred to food through hands, utensils, equipments, flies etc.

3.Presence of flies, cockroaches, rats, in the food environment that act as vectors of the disease.

Clinical Features• Fever• diarrhea• vomiting • abdominal pain • headache• prostration and • malaise.

• In severe cases– septicaemia – Leucopenia– endocarditis– pericarditis.

Campylobacteriosis• Campylobacter jejuni and Campylobacter coli cause food

poisoning and are associated with acute enterocolitis in man.

• Campylobacter jejuni occur in large numbers in cattle feces, and poultry as normal flora.

• Campylobacter coli are commonly associated with human diarrhoea.

• Incubation period ranges between 2-11 days.

• Fever • Diarrhoea with blood and mucous• Abdominal pain• Nausea• Vomiting.

• The jejunum, ileum and colon are primarily affected resulting in acute inflammation and abscess formation.

• The disease is self-limiting.

Clinical features

Transmission• Infection occurs by ingestion of contaminated

food-stuffs:– meat from infected animals(poultry) – unpasteurized milk and – possibly cross-contamination from these

sources to foods eaten uncooked or unrefrigerated.

Escherichia coli food borne infection

• Escherichia coli are potential food poisoning pathogens which are widely distributed.

• E. coli strains involved in food borne infection fall into the following groups:1. Enteropathogenic E. coli (EPEC), 2. Enterotoxigenic E. Coli (ETEC), 3. Enteroinvasive E. coli (EIEC) and 4. Enterohemorrhagic E. coli (EHEC).

Enterotoxigenic E.coli food borne infection

• Main cause of endemic diarrhea in developing countries.

• ETEC produce two toxins which may be labile toxin (LT) or Stable toxin(ST) or both.

• It is toxigenic but not invasive type.

• Transmission is by contaminated food and water.

Clinical features

Common features• profuse, watery diarrhea

with no blood

• abdominal cramping.

Less common features• Fever• Nausea with or without

vomiting• Anorexia• Headache• Muscle aches and bloating

Traveler's Diarrhea

• People travelling to developing countries are at high risk of developing diarrhea.

• ETEC is the leading cause of Traveler’s diarrhea in Asia, Africa, Latin America.

• IP- 5-15 day.

Enterohemorrhagic E. coli• EHEC infection is caused by Escherichia coli

serotype O157:H7.• Toxin is secreted called as verocytotoxin or Shiga-

like toxin.

• causes hemorrhagic colitis in humans, diarrhea, abdominal pain, fever and vomiting.

• complications - bloody diarrhea, acute ulcerative or ischemic colitis and HUS(Haemolytic uraemic syndrome).

Shigellosis (Bacillary dysentery)

• Shigellosis is caused by members of the genus Shigella. – Shigella dysenteriae, – Shigella flexneri, – Shigella boydii and – Shigella soneii.

• The infective dose is very small 10-100 bacilli.

• Spread is by fecal-oral route.

Clinical symptoms• The illness begins 1 to 4 days after ingestion of

bacteria and may last 4 to 7 days.

• Symptoms include :– fever, – watery or bloody diarrhea with mucous,– nausea or vomiting, – abdominal pain, – dehydration

Cholera

• Cholera is caused by Vibrio cholera.

• Vibrios are ingested in drink or food. • The organism multiply in the small intestine

to produce a very potent enterotoxin, which stimulates a persistent out pouring of isotonic fluid by the gut mucosal cells.

Transmission

• Man is the only natural host of the cholera vibrios. • Spread of infection is from person-to-person,

through contaminated water or foods.

• Shrimps, contaminted water, shellfish and vegetables are the most frequent carriers.

Clinical symptoms• Cholera is typically characterized by the sudden onset

of effortless vomiting and profuse watery diarrhea mucous flakes.

• 20-30 stools per day

• Death may occur in 12 to 24 hrs due to rapid dehydration and hypovolemic shock.

Vibrio parahemolyticus

• Vibrio parahemolyticus is a pathogenic bacteria causing food borne infections, whose natural habitat is the sea.

• Human infections occur solely from sea foods such as oysters, shrimps, crabs, lobsters, fish,clams and related shellfish.

Clinical features

• V.parahemolyticus causes gastro-enteritis and extra intestinal infections in man.

• The incubation period is 16 hrs• Symptoms include:

a. Diarrhea e. Vomitingb. Cramps f. Headachec. Weakness g. Chills d. Nausea

Vibrio vulnificus foodborne infection

• Vibrio vulnificus causes a severe foodborne infection, often associated with eating raw oysters.

• In immuno-compromised hosts, V. vulnificus infections can cause fever, nausea, myalgia and abdominal cramps.

• IP- 24-48 hours.

Yersinia enterocolitica infection• This organism has been isolated from beef,

lamb, pork, sea foods, vegetables milk and cakes, vacuum-packed meat.

• Symptoms includes:• Fever• Diarrhea• Abdominal cramps• Vomiting• Headache

• The organism is shed in stools up to 40 days following illness.

Clinical Features

VIRAL FOODBORNE INFECTIONS• Viruses are common pathogens transmitted

through food.

• Hepatitis A and Norwalk-like virus (Norovirus) are the most important viral food borne pathogens.

• These viruses are highly infectious and may lead to widespread outbreaks

Hepatitis A• Incubation period is long, average of 30 days.

– Fever – Muscle aches– Headache– Loss of appetite– Abdominal discomfort– Weakness and fatigue

Norwalk-like virus (Norovirus)• Infection is mild, incubation period of 3 days.

• Consumption of raw oysters.

• Clinical manifestations include: vomiting and diarrhea, and rarely convulsions.

FOOD BORNE INTOXICATIONS

FOOD BORNE INTOXICATIONSThese are diseases caused by consumption of food

containing:

1. Biotoxicants : which are found in tissues of certain plants and animals. Eg- Mushroom toxicity.

2. Metabolic products (toxins): formed and excreted by microorganisms, while they multiply in food, or in gastrointestinal tract of man.

3. Poisonous substances: which are present in the food during production, processing, transportation or storage.

Food borne intoxications…… Food borne intoxications have short incubation

periods (min to hours) and are characterized by lack of fever.

Food borne intoxications can be classified into:a. Bacterial intoxicationsb. Fungal intoxicationsc. Chemical intoxicationd. Plant toxicants, and e. Poisonous animals.

BACTERIAL FOOD BORNE INTOXICATIONS

1. Staphylococcus aureus2. Bacillus cereus 3. Clostridium perfringens 4. Clostridium botulinum

Staphylococcus aureus food borne intoxication

This is a type of food borne intoxication which is caused by consumption of food contaminated with staphylococcal enterotoxin produced by the certain strains of Staphylococcus aureus.

The five enterotoxins are: Staphylococcal enterotoxinAStaphylococcal enterotoxin BStaphylococcal enterotoxin CStaphylococcal enterotoxin DStaphylococcal enterotoxin E All the five enterotoxins have the similar

potency. Individual strains of S.aureus may produce one or more of enterotoxin types while growing in food.

Toxin production

• Toxin production occurs at growth temperature 12-44oC, pH 4.2 and salt concentration of ≤10%.

• No toxin production occurs at temperatures below 12oC, pH < 4.2 and > 10 % salt.

Nature of enterotoxins

• All the staphylococcal enterotoxins are heat stable and ordinary cooking procedures, pasteurization and drying do not inactivate these enterotoxins.

• pH stable and resistant to most proteolytic enzymes (trypsin, chymotrypsin, renin, and pepsin).

Causative foods• Milk products: Non meat products:

pasteurized milk egg yoghurt egg products vegetables cereal

• Meat products :FishShellfishPoultry

Clinical features• Incubation period is 1-6 hr.

• At least 1.0 µg of enterotoxin causes infection

• nausea, vomiting, abdominal cramps, sometimes diarrhea with prostration.

• Duration of illness is 24-72 hrs.

Bacillus cereus food borne intoxication

• This is a food borne intoxication caused by consumption of enterotoxins produced by some strains of Bacillus cereus.

• The organism produces the following enterotoxinsa. Two diarrhoeal enterotoxins: -

hemolysin enterotoxin, non-hemolytic enterotoxin

b. Emetic toxin

Causative foods• Meat • Eggs • Dairy products• Cereal dishes e.g. rice, spice, mashed have been

involved in B. cereus poisoning.

Clinical manifestations

1.Emetic syndrome

• nausea• Vomiting• abdominal cramps

Rice and pasta based foods are involved 

2. Diarrheal syndrome

• profuse diarrhoea (watery stool)• abdominal cramps• tenesmus (rarely vomiting) • Fever is absent. Meat, vegetables ,dried beans and cereals

Clostridium perfringens food borne intoxication

• food borne intoxication caused by C perfringens enterotoxin (CPE) produced in the GIT by enterotoxigenic strains of C. perfringens.

• found in the soil, dust, water, sewage marine sediments, decaying materials, GI tracts

Cause of intoxication

• ingestion of contaminated food with large numbers of C. perfringens type A & some type C and D

• The food poisoning strains are heat resistant and survive heating at 100oC for 1 hr.

• Foods poisoning occurs when the level reaches 107-108 cells/g of food

Causative foods• Red meats, chickens, fish, pork, fruits, vegetables.

• Contamination of slaughter meat from containers, handlers, dust, and water.

• The food involved are those that are prepared one day and served the next day.

• The heating of such foods is inadequate to destroy heat resistant endospores.

Clinical features

• IP- 8-24 hours after ingestion

• Symptoms include nausea, intestinal cramps, pronounced diarrhea,

• Vomiting is rare and the illness takes a duration of 1-2 days.

Clostridium botulinum foodborne Intoxication

• Botulism is a type of food poisoning caused by consumption of enterotoxins produced by strains of Clostridium botulinum.

• Intoxication is caused by toxins A, B,C1,C2,D,E, F & G.

• Spores of C. botulinum type A can survive temperatures of 120oC.

• Type E strains are non-proteolytic while the rest are proteolytic.

Growth characteristics• Toxin production occurs at temperature range

between 25-30oC. • Proteolytic strains produce an active botulinal

toxin, while non-proteolyic strains produce inactive pro-toxin that require activation by trypsin.

Non-proteolytic strain Inactive pro-toxin

Active Toxin

TRYPSIN

Characteristic of Botulinal toxins

• These toxins are neurotoxins, highly toxic, heat labile.

• The toxins can resist the action of the gastric and intestinal juices.

• Botulinal toxin is one of the most lethal poisons known.

• The calculated lethal dose for an adult person is 10 µg.

Types of foods implicated• Foods associated with anaerobic conditions such as

spoiled canned meat, or hams and bacon stacked without air access, are particularly liable to be infective.

• Uncooked fresh foods are safe because they are eaten

before the toxin has had time to develop.

Clinical featuresAdult botulism• The period of incubation in man is 12-72 hrs. • Nausea headache Vomiting dryness of skin Fatigue respiratory failure Dizziness lack of fever,

Nerve paralysis double vision

• Duration of illness 1-10 days.

Infant botulism• Occurs in infants less than 1 year of age through

ingestion of spores in honey.

• The spores germinate in the GIT with toxin production.

• A high number of spores are found in feces of infants during acute phase of the disease.

• Constipation,poor feeding,lethargy,weakness, floppiness

Fungal intoxications

• These are caused by consumption of metabolites called as mycotoxins produced by fungi, while growing in food.

• Grains(Poor dry storage), oilseeds, fruits and vegetables are mostly involved.

• Of significance to public health is aflatoxicosis.

Aflatoxicosis• Aflatoxicosis is caused by Aflatoxins produced by the

fungi, e.g. Aspergillus flavus and Aspergillus parasiticus

• Four types of aflatoxins have been described i.e. aflatoxin B1, B2, G1 and G2.

 

Effects of aflatoxins

• large doses are lethal : acute hemorrhagic syndromes.

• Medium doses are sub-lethal : histotoxic changes.

• small doses for long term : liver tumors as these are potent carcinogens.

CHEMICAL FOODBORNE INTOXICATION

• This is a type of food borne intoxication arising from consumption of food containing poisonous chemicals.

• These may be intentionally or unintentionally added to foods as a result of producing, processing, transporting or storage.

Chemical substances involved

Chemical food borne intoxication involve the following substances:

• Heavy metals e.g. antimony, mercury, arsenic, flouride, lead, cadmium, cyanide etc.

• Pesticides and insecticides .• Herbicides and Fungicides.• Radionuclides e.g. radium, barium, iodine

isotopes etc.

Clinical features• very short incubation period(mins to few hrs).• mainly involved are GIT and CNS :

– Nausea– headache– Convulsions– gastrointestinal irritation– abdominal cramps– vomiting and diarrhea– Pallor– Cyanosis– blurred vision

Biotoxications• These are disorders resulting from ingestion of

a poisonous substance (a biotoxin) present in the body of a plant or animal.

• derived from plants or animals as a result of metabolic activities.

Animal biotoxications

• This type of intoxication occurs as a result of consumption of poisonous animals.

• One of the example is puffer fish, a delicacy of China.

Clinical Diagnosis• Specimen collection:

feces/stool left-over food vomitus

• Microscopy: Microscopy of faeces is done to detect motility of the organism ,and ova or cyst of parasite.

Wet mount hanging drop staining.

• Culture: Selective & non-selective medias are used according to the suspected organism.

• Salmonella & Shigella- – XLD(xylose lysine deoxycholate )– HEA(hekton enteric agar)– SSA(salmonella shigella agar)– WB(wilson blair)– Buffered gycerol saline.

• Vibrio cholerae-– Alkaline peptone water– TCBS(thiosulfate citrate bile sucrose)– Cary blair

• Staphylococcus aureus-– Mannitol salt agar– Milk salt agar

• Bacillus cereus-• MYPA(mannitol egg yolk phenol red polymyxin agar)• PEMBA(polymyxin B egg yolk mannitol bromothymol blue agar).

• Anaerobes-• RCMB(robertson cooked meat broth).• Thioglycollate broth.

• Campylobacter-• Skirrows• Butzler• campy

Microscopy light microscopy

electron microscopy

stool culture Food tissue culture poisoning

toxin assay serology ELISA,LAT,Eletrophoresis

P.C.R. – Specific identification

Parasite(ova,cyst)

Hanging drop

Gram stain

Ziehl-Neelsen stain

virus

Direct

Enrichment

Selective

Virus

Mac Conkey

Selenite FB, Tetrathionate Alkaline peptone water

Wilson blair, TCBs, XLD, DCA

Identification

Serotyping

Antibiotic sensitivity &Biochemical reaction

• Serological Diagnosis: detection of toxin ELISA LAT Electrophoresis

• Molecular techniques: Polymerase chain reaction

Preventive Measures

• Regular hand-washing• Sanitary improvements.• Health Education: Food handler should be educated in

matter of the clean habits, and personal hygiene.• fast cooling of food so that the remaining spores might

not germinate.• Thorough washing and sanitation of containers while

handling food items.

Bibliography

• Textbook of Microbiology by Ananthnarayan and Paniker’s:9th edition.

• Essentials of medical microbiology by Apurba Sankar Sastry.

• Principles and practice of infectious diseases by John E. Bennet, Raphael Dolin and Martin J.Blaser :8th edition.

• Diagnostic Microbiology by Bailey and Scott’s :12th edition.

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