Foodborne Pathogen and Disease Foodborne Pathogens a biological

Foodborne Pathogen and Disease

Foodborne Pathogens a biological infectious agent (Microorganism) that causes Foodborne illness to host (referred to as food poisoning) is any illness resulting from the consumption of contaminated food.

Foodborne Pathogens: • Foodborne pathogens are the leading causes of illness and death in less developed countries killing approximately 1. 8 million people annually. • In developed countries foodborne pathogens are responsible for millions of cases of infectious gastrointestinal diseases each year, costing billions of dollars in medical care and lost productivity.

• New foodborne pathogens and foodborne diseases are likely to emerge driven by factors such as pathogen evolution, changes in agricultural and food manufacturing practices, and changes to the human host status. • There are growing concerns that terrorists could use pathogens to contaminate food and water supplies in attempts to incapacitate thousands of people and disrupt economic growth.

Pathogenic microorganisms 1. Intoxication : - Staphylococcus aureus - Clostridium botulinum - Bacillus cereus 2. Infection : - Salmonella - Clostridium perfringens - Vibrio - Phathogenic E. coli

Staphylococcus aureus TAXONOMY • Gram positive coccus (producing an exotoxin) Source of contamination of food - nose and skin of humans and animals - high level in people with - skin infection - heavily colonised skin disease

• Contamination by food handler • Eliminated by pasteurization • Microwave decreases counts • Fat/ sugar/ salt protects the organism • Usually about 106 / g needed to produce sufficient toxin • Generally low numbers are allowed in food

GROWTH REQUIREMENTS * Temperature range 7 - 48 o C (optimum 37 o. C) * p. H range 4 - 9. 8 (optimum 6 - 7) * Facultative anaerobe

REQUIREMENTS FOR TOXIN PRODUCTION • Range is more limited than growth range optimum temperature 40 – 45 o C Aw above 0. 85

Staphylococcal Exotoxin (Enterotoxin / Neurotoxin) * Resistant to proteolytic enzymes e. g. trypsin in the gut * Resistant to heat

Mechanism of Activity • Toxin (exotoxin) is performed and ingested in food • Stimulates neural receptors in the gastrointestinal tract • Vomiting within approx 4 hours (1 -6 hours) after ingestion of toxin • The toxin can also induce diarrhea, nausea, headache

Examples of foods implicated in outbreaks • • • Salted meats Cold cooked meats Poultry Custard Cream filled bakery products (whipped cream) • Mayonnaise • egg

PREVENTION MOST OUTBREAK ASSOCIATED WITH ONE OR MORE OF : • Inadequate in refrigeration • Food prepared in advance • Poor personal hygiene • Moderate cooking or heat processing • Holding food in warmer SO… * Control post-process contamination * Control temperature abuse (cooking/ holding/ refrigeration) * Handle food correctly * Good quality raw material

Salmonella TAXONOMY • • Enterobacteriaceae Gram Negative, Short Rod Non spore forming Peritrichous flagella RESERVIOR • Intestinal of domestic and wild animal • Water, Sewage, Environment

GROWTH REQUIREMENTS * Temperature range optimum 37 o. C 42 o. C used for selective enrichment * p. H range 4 -9 * Facultative anaerobe

Found in many foods : • Contamination directly or indirectly with animal or human feaces - Raw/Undercooked eggs - Uncooked meat - Raw milk and milk products - Poultry and poultry products - Skim milk powder - Ice-cream - Mayonnaise - Chocolate - Cantaloupes

Clinical • • • Diarrhoea Vomiting Antibiotics minimal effect Organism may be excreted for weeks Some outbrakes have shown very low infective dose causing death in infants, elderly and immunosuppressed.

PREVENTION • Correct food hygiene – direct or indirect feacal contamination • Correct food processing – heating / cooling / storing. • Correct personal hygiene to control secondary spread • Food handlers should have consecutive negative feacal cultures before returning to work with food.

Indicator Microorganisms

Coliform • is the name of a test for the Enterobacteriaceae family. • commonly-used bacterial indicator of sanitary quality of foods and water. • They are defined as rod-shaped Gram-negative non-spore forming organisms. • Some genus can ferment lactose with the production of acid and gas when incubated at 35 -37°C. • abundant in the feces of warm-blooded animals, but can also be found in the aquatic environment, in soil and on vegetation. • they are easy to culture and their presence is used to indicate that other pathogenic organisms of fecal origin may be present. Fecal pathogens include bacteria, viruses, or protozoa and many multicellular parasites

Escherichia coli • • Member of the coliform group Gram Negative, rod and Non-sporulating Facultative anaerobic ferment lactose at 44°C in the fecal coliform test • When cultured on an EMB plate, a positive result for E. coli is Metallic sheen colonies on a dark purple media.

Reference Adams, M. R. and Moss, M. O. , Food Microbiology, 2008