Prevention Of Food Contamination By Pathogenic

Microorganisms

Dr: Dina Ramadan LithyMicrobiology specialist central health laboratory

Cairo . Egypt

Pathogenic Microorganisms Very small ,Single cell organisms, seen by Very small ,Single cell organisms, seen by

microscope only.microscope only.

Eating or drinking food that contains harmful Eating or drinking food that contains harmful microbes can cause food poisoning.microbes can cause food poisoning.

NotNot all food all food APPEARINGAPPEARING normal normal is safeis safe to eat, it to eat, it may be contaminated by harmful bacteria which may be contaminated by harmful bacteria which cause food borne illness cause food borne illness

Apr 10, 20232

Microbiological pathogens

Food poisoning

Infective food poisoning Toxic food poisoning

Some bacteria produce toxins ,these toxins cannot be removed or inactivated by cooking.

Examples Staphylococcus aureus, Clostridium perfringens

Occurs as a result of eating food contaminated with bacteria itselfExamples; Salmonella, Listeria and Escherichia

coli .

Common Food borne Bacteria

Salmonella

one of the most common causes of food poisoning. Symptoms last 4-7 days without treatment. Salmonella is killed by cooking and pasteurization, But it can contaminate the food processing area

and transmitted to another food item.

Source Raw poultry and eggs Undercooked poultry and meat

Apr 10, 20235

Staphylococcus aureus

It is commonly found on the skin , hair ,

noses and throats of people and animals. It can multiply quickly at room

temperature and produce a toxin

that causes Food poisoning

Source ; Salads, macaroni Bakery products, cream pies,

and chocolate éclairs Milk and dairy products, Apr 10, 20236

EHEC (Enterohemorrhagic E. coli)

E. coli (0157:H7)Lives in intestines of healthy cattle It produce enterotoxin causes hemolytic

inflammation of the intestines results in bloody diarrhea hemorrhagic uremic syndrome (HUS)

• Source :– Undercooked hamburger , salami– Unpasteurized milk, Well water– Fruits and Vegetables

Apr 10, 20237

Shigella It causes diarrhea in human which called bacillary

dysentery,, Shigellosis is a cause of traveler’s diarrhea from food and water contaminated in developing countries.

Source : Salads and sandwiches Raw vegetables

Apr 10, 20238

Listeria

It is widespread in nature, in soil and water . It grows at low temperature and in refrigerator. It is very dangerous pathogens for pregnant

women; it can transmit from mother to baby through placenta results in abortion.

Source Ice-cream ,unpasteurized milk,

soft cheeses

Ready-to-Eat foods, salads Apr 10, 20239

Vibrio

this bacteria found in warm coastal areas and in the summer months when water gets wormer

V. parahaemolyticus typically causes non-bloody diarrhea V. cholerae cause watery diarrhea (called "rice water stools" It cause electrolyte imbalance by Losing body fluids Severe cases, 12 - 20 liters of liquid lost in a day Untreated cases - Mortality Rate about 50% By treatment with electrolytes mortality 1%Source : Raw or undercooked fish and shellfish Drinking contaminated water Eating food washed or made with contaminated water Apr 10, 202310

Clostridium perfringens

One of the most common spore forming bacteria causing food poisoning.

Cooking kills  Bacterial  cells, but the spores grow into new cells.

When food prepared in large quantities and kept long time before serving it cause infection

Outbreaks usually linked to institutions (hospitals, school cafeterias, and prisons).

Sources such as Beef and Poultry

Apr 10, 202311

Clostridium botulinum

This is one toxin producing bacteria producing neurotoxin

Leads to flaccid paralysis. (Botulism) is rare but fatal caused by eating

food contamination as it end by death .

Sources: Honey, home-canned vegetables and fruits, and

salted fish .

Apr 10, 202312

Bacillus cereus

It is type of bacteria that produces toxins. These toxins can cause two types of illness:

diarrheal toxin, emetic toxin, It presents in food and can multiply quickly at

room temperature

Source : Rice , sauces, soups Food that have stayed too long at room

temperature Apr 10, 202313

Symptoms of food poisoning

General symptomsFever, chills, malaise , aches, swollen lymph nodes• Salmonella typhi,• Listeria monocytogenes,• Campylobacter. Jejuni

Upper GIT signsNausea, vomiting, abdominal pain, diarrhea &• S. aureus and its toxins• B. cereus and its toxin

Apr 10, 202315

Lower GIT signsLower abdominal cramps & diarrhea :• Clostridium perfringens,• Bacillus cereus• Salmonella, Shigella,

Neurological signsVisual disturbances, vertigo

& paralysis

Clostridium botulinumApr 10, 202316

The main cause for food poisoning is eating food contaminated by Bactria

The bacteria need suitable condition to multiply as temperature, moisture, oxygen and have some protein,

In suitable condition

One bacteria multiply to more than four million bacteria in eight hours, and make food unsafe to eat within few hours.

controlling bacteria

Controlling bacteria, make food safe . and Prevent food poisoning begin from kitchen

by:

controlling bacteria Cooking at proper temperature destroys harmful

bacteria that may be present in food

Chilling By following Cooling , Freezing rules control bacterial growth can be controled

Cleaning surface , products , wash hands and

good hygiene.

Separation to prevent cross-contamination via hands, utensils, surfaces

Temperatures control Most types of pathogenic

bacteria can grow in temperature from 41ºF to 140ºF (5ºC to 60ºC) which called temperatures danger zone (TDZ),

To prevent bacteria from growing, we must set the refrigerator temperature not higher than 39ºF (4ºC).

Refrigerator must not be too full, as Cold air must circulate to keep food safe.

cooking Heating the food for enough time and at high

temperature, kill harmful microorganisms Always stir while heating and rotate food to

distribute heat. Avoid :

Interrupted cooking. Never refrigerate partially cooked products to be later cooking in the oven.

Traditional recipes for limited cooking: as eating Raw oysters, raw ground beef, and soft boiled eggs.

Microwave cooking

Microwaved food may have cold spots which are ideal for bacterial growth.

When use it for reheating food it must be leftovers to minimum of 165ºF (74ºC) and serve immediately.

Freezer temperatures it Slow bacterial growth but do not necessarily kill

bacteria. If food has been temperature-abused before

freezing it will be unsafe upon thawing Food must be stored properly to be safe.

The Thawing law Never defrost food at room temperature. Thawing food in the refrigerator. For a quick thawing, thawing in the microwave if

cooking immediately.

leftoversRemember Refrigerate food within 2 hours. Keep leftovers in small containers for quick

cooling. Use a cooler or ice pack to keep perishable

food cold, especially on hot summer days. When in doubt, throw it out!

Keep Clean

Wash hands, utensils, and surfaces, in hot, soapy water before and after food preparation

For protection against bacteria use disinfectants cleaners or a mixture of bleach and water on surfaces.

27

Keep Clean

All cutting boards Cutting boards (including plastic, acrylic, and

wooden boards) Should be run through the dishwasher or

washed in hot, soapy water after each use

Produce: Wash raw produce under running water. Use vegetable brush to remove surface

dirt. Cut away any damaged or bruised areas .

Keep Clean

Wipe up spills in the refrigerator,

microwave immediately.

Towel If using cloth towels, wash them in the

boiling water Using paper towels to clean up kitchen

surfaces. Then , throw it away

separation

Separation to prevent cross contamination: Safely Separate

Separate raw meat and seafood

from other food in refrigerator

to avoid cross-contamination

Clean up Wash hands, cutting boards, dishes

after contact with raw meat,

or unwashed products.

Take two separate

USE one cutting board , Knife etc ,for raw meat, and another one for salads and ready-to-eat foods.

Never place cooked food on the same plate or cutting board which previously held raw food.

Handling dairy products , raw meat, then prepare salads, sandwiches can create “Cross-contamination”.

Restaurants staff personal hygiene

Clean hands and clothing. Minimize jewellery on hands. Tie-back or cover hair. Wearing gloves. Clean and short fingernails. Sick personal not prepare

food Avoid :

touching face and hair. cough or sneeze over food. taste food with your fingers.

They must have Basic food safety education and correct personal hygiene:

Pest Control Food must Stored in tightly closed containers to

keep out pests.

Flies: Windows and doors must properly closed. Use fly proof mesh if possible.

After applying pesticide spray, always maintain a time gap before reusing kitchen to prepare food , also wash utensils before reuse

Ants: Always keep kitchen countertops clean

Rodents: Use food traps. If using rat poisons, don’t keep it for extended period.

Hazard Analysis and Critical Control Point

(HACCP)

The HACCP It is the system that is required for any food

business or organisation in most countries.

The joint FAO / WHO Codex Alimentarius Commission recommends the HACCP approach to enhance Food Safety in all process of food production.

The HACCP Advantages

Gives insight in the critical control points of the product process

Gives trust for the consumer that products are produced safely and hygienically

Reduces the costs of food borne illness.

The HACCP disadvantages:

Need to train supervisors, managerial and

production staff

Reduced Staff time available for other tasks

Increased production , implementation and supervisory costs

Reduced flexibility in production process and introduction of new products.

Food pathogens enter food chain at multiple points.

Fight bacteria by cook , clean , chill and separate.

Maintain a clean and sanitary environment for all areas of food production.

Apply good personal hygiene.

Prevent cross contamination in the kitchen.

All organization dealing with food production must enforced by governments to applying HACCP system

Remember to make food safe