Foodborne and Waterborne Pathogens Flashcards
What is the main cause of foodborne illness?
Intrinsic natural toxins
- Legume toxins
- Algal toxins
- Mycotoxins
What are the factors affecting growth of microbes in food?
Nutrients
Antimicrobial barriers
Antimicrobial agents
pH
Why do microbes grow well on human food?
Because the nutrients microbes require for survival and growth are the same as those we require
What is the main antimicrobial barrier in food?
Skin
- Low water activity
- Low nutrient content
- Resistant to decay
What antimicrobial does garlic produce and why?
Allicin
- In response to physical damage
- Limits microbial intrusion
What features of food do microbes prefer?
Moist
Neutral pH
Why might animal commensal organisms which are harmful to humans accumulate during slaughter?
If removal of internal organs and the guts of animals is not performed correctly or hygienically
What are the defences against infection found in the intestinal tract?
Acidic environment
Bile salts
Rapid flow of material
Proteolytic enzymes
Why does infectious dose vary between individuals?
Because different host have different health and immunity
What microbe causes campylobacteriosis?
Campylobacter jejuni
What is campylobacteriosis?
The most common cause of food poisoning
What is the major source of campylobacteriosis?
Raw chicken
How do campylobacteriosis pathogens cause infection?
Disrupt the membrane of the cells lining the gut so they cannot regulate fluid and chemical balance
What is the bodies response to infection by campylobacteriosis?
Inflammation and bleeding in local damaged tissue
What microbes cause salmonellosis?
Salmonella species
How do salmonellosis pathogens cause infection?
Invade cells in the epithelium of the small intestine and produce toxins
In what patients can secondary infection occur as a result of salmonellosis?
Vulnerable patients - those with compromised immune systems
What is vero-cytotoxic E.Coli associated with?
Beef or contamination within cattle faeces
What are the symptoms of vero-cytotoxic E.Coli?
Toxins produced cause severe stomach cramps, diarrhoea, vomiting and significant bleeding from the gut
What microbes cause Listeriosis?
Listeria monocytogenes
In what foods is listeriosis common?
Soft cheese
Vacuum packed food
Unwashed vegetables
What symptoms does listeriosis cause in healthy people?
Flu like symptoms
What symptoms does listeriosis cause in pregnant people?
Abortion
Septicaemia in baby
Meningitis in baby
What are the two main preformed toxins in food?
Bacillus cereus
Staphylococcus aureus
What does bacillus cereus result from?
Poor food storage
What does bacillus cereus do on food?
Germinates and multiplies
Produces heat stable spores which cannot be eliminated by heating
What does staphylococcus aureus result from?
Poor hand hygiene
What does staphylococcus aureus do on food?
Multiples and produces enterotoxins which are heat stable and result in rapid onset vomiting
What types of microbes are foodborne diseases often a result of?
Viruses and fungi
Why do protozoa not tend to cause foodborne disease?
They are affected by heat and are therefore eliminated during cooking
What are the three entry routes of waterborne disease agents?
Gastrointestinal
Respiratory
Through the skin
What microbe is cholera caused by?
Vibrio cholerae
What are the symptoms of cholera?
Diarrhoea
Severe dehydration
Potentially death
How do cholera pathogens cause infection?
Act on mucosal epithelium of the digestive tract
Prevent regulation of sodium and chloride resulting in massive loss of water from cells
What microbe causes cryptosporidiosis?
Cryptosporidium parvum = protozoa
What are the symptoms of cryptosporidiosis?
Abdominal pain
Diarrhoea
Weight loss
Apetite loss
Why does cryptosporidiosis cause disease through water and not food?
Water = oocysts are resistant to chlorine and disinfectants Food = killed by heating
What microbe is legionnaires disease caused by?
Legionella pneumophila
What are the sources of legionnaires diseases?
Inhaling contaminated air
On shower heads
What are the symptoms of legionnaires disease?
Severe pneumonia
What group of people are more at risk from legionnaires disease?
Elderly
What microbe causes leptospirosis?
Leptospira interrogans
How do leptospirosis bacteria enter the body?
Through breaks in the skin
What are the symptoms of leptospirosis?
Influenza like illness
What complications can leptospirosis cause?
Jaundice Hepatitis Kidney damage Damaged blood vessels Meningitis
