Foodborne pathogens Flashcards
E. coli Pathogens
- Enterotoxigenic, produces toxin E. coli (ETEC)
- Enteroinvasive, invades cells E. coli (EIEC)
- Enteroaggregative, forms clumps E. coli (EAEC)
- Enteropathogenic, causes inflammatory response E. coli (EPEC)
- Enterohemorrhagic, produces toxins E. coli (EHEC)
- Shiga toxin producing E. coli E. coli (STEC)
- An organism that has changed the U.S. food safety system 1992- hamburger fast food chain, new laws, HACCP
- An emerging pathogen
- Zero tolerance in raw ground beef
E. coli O157:H7
Important Characteristics of E. coli O157:H7
- Low infectious dose: 10 cells
- Unusual acid tolerance
- Resistance to environmental stress
- Severe disease consequences: bloody diarrhea, HUS, TTP, death
- Diseases affecting all age groups, more severe in young children
HUS is
Hemolytic uremic syndrome, causes Kidney failure
TTP is
Thrombotic thrombocytopenic purpura, causes blood clotting Fatality rate 90%
Reservoirs of E. coli O157:H7
• Ruminants (cattle, sheep, deer) and other animals
- Undercooked ground beef
- Fresh produce and sprouts
- Unpasteurized fruit juices
- Manure
- Unpasteurized milk
- Swimming water
Transmission vehicles of E. coli O157:H7
Mode of Transmission of E. coli O157:H7
- Ingestion of contaminated food • Contaminated water
- Animal-to-person, Zoonotic Disease
- Person-to-person
Disease Symptoms of E. coli O157:H7
part 2#
-Non-bloody diarrhea, asymptomatic infection
-Hemorrhagic colitis (HC)
Bloody diarrhea, produces shiga toxin in intestine
- Death
Treatment of E. coli O157:H7
Do not administer antibiotics!
Some antibiotics increase Shiga toxin production, thus progress to HUS . ✅❌
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Control Methods Outbreak of E. coli O157:H7
- Improve hygiene at farm level
- Pasteurize milk and juice
- Meat irradiation
- Proper cooking
Poor countries, poor sanitation, infantile diarrhea, non-toxic
Enteropathogenic E. coli (EPEC)
Invade mucous cells will have blood and mucous in stool
Enteroinvasive E. coli (EIEC)
Produces toxin –does not invade mucous cells – common with
travelers to foreign countries
Enterotoxigenic E. coli (ETEC)
Produces toxins, physical alteration of intestine
Enterohemorrhagic E. coli (EHEC)
Forms clumps in intestinal tract, produces toxins
Enteroaggregative E. coli (EAggEC)
is main symptom in newborns
Diarrhea
What is the Invasive.
the bacteria invades the epithelial cells of the
colon via an Outer membrane protein that is plasmid
associated
Symptoms are like dysentery caused by Shigella.
• Fever • Cramps
• Bloody diarrhea
Enteroinvasive E. coli (EIEC)
Enterotoxigenic E. coli (ETEC)
Travelers diarrhea
Profuse watery diarrhea
Does not invade or destroy cells lining the intestine
can produce LT, ST or both
Enterotoxigenic produce ST after is
colonizes the intestinal tract
Labile Toxin (LT) is destroyed at
60°C for 30 min
LT is similar to
cholera toxin
Thrombotic thrombocytopenic purpura – Similar to HUS, occurs in
the elderly with brain damage
- Persistent diarrhea in infants
- Long thin structures –adhesions- causes aggregative clumping
- Produces shiga - like toxin
Enteroaggregative E. coli (EAggEC)
What is the Microbiology of Campylobacter?
- Thermophilic 42°C
- Minimum growth temperature 30°C
- Microaerophilic 85% N2, 10% CO2, 5% O2
- Slow growth • Fragile bacteria
Family Campylobacteraceae is a
Gram-negative
Responsible for one of the most frequently occurring forms of gastroenteritis in humans
Campylobacter
Campylobacter classified as
vibrio
causing spontaneous abortion in cattle and sheep
Campylobacter
Epidemiology of Campylobacter
Campylobacter jejuni and Campylobacter coli
Campylobacter Low infectious dose -
<500 cells
Reservoirs of Campylobacter
Poultry, cows, pigs, birds, rodents, sheep, horse, pets
Vehicles of Campylobacter
- Poultry (50-70% of outbreaks)
* Raw milk, untreated water, beef, pork pet contact
Campylobacteriosis
Watery diarrhea,
fever,
abdominal pain
Complications of Campylobacteriosis
arthritis, HUS, septicemia, meningitis and Guillain-
Barre Syndrome
Treatment of Campylobacteriosis
antibiotics of choice are: Ciprofloxacin and erythromycin
Campylobacteriosis have Growing resistance to antibiotics
Especially to Ciprofloxacin.
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Controls of Campylobacteriosis:
-Organism is very heat sensitive, so adequate cooking is all that is needed. • Use chlorinated water • Pasteurize milk • Cook chicken to proper temperature • Use food thermometer • Prevent cross-contamination
Warm blood animals are reservoirs of
Campylobacter jejuni
Poultry 80 % of broilers contaminated with………… turkeys
and ducks also involved
• Red meat 5%
• Raw milk
• Poultry and raw milk are the main sources
Campylobacter jejuni and Campylobacter coli
Risk factors:
• Untreated water
• Unpasteurized milk – leading cause of foodborne outbreaks (from feces
of cows, 60% of cows are carriers)
• Having a cat in the house – Organism directly transmitted to humans
• Pet; cats and dogs account for 6% of human cases
• Eating undercooked chicken – sporadic cases
Campylobacter jejuni and Campylobacter coli
Salmonella Occurs widely in natural environment found in
humans,reptiles, turtles, dogs, cats, animals, and eggs.
Salmonella Most common species implicated in foodborne outbreaks
S. Typhimurium, S. enteridtidis
Salmonella are mesophile, What’s means?
it grows best in moderate temperature, neither too hot nor too cold.
Characteristics of Salmonella
Gram negative non-spore forming rod facultative Mesophilic Spread of infection is by zoonosis Can survive in sweeper dust for 10 months Is destroyed by cooking
Salmonella is ingested and goes to
intestine
Salmonella causes Membrane ruffling that allows it entry into the
mucosal cells
Salmonella remain and multiply in the
phagosome
Salmonella Symptoms
gastroenteritis
Factors that have influenced development of antibiotic – resistance
- Overprescribing antibiotics
- Over counter public access to Ab 3. Incomplete use of Ab
- Storage of unused Ab for future use.
- Parental pressure to treat children with Ab.
- Prophylactic use of Ab in animals to promote growth
Staphylococcus aureus
• Greek term Staphy means a
a bunch of grapes, grain or berries
Competes with Salmonella as the most prevalent cause of food related illness
Staphylococcus aureus
Leading causes of Staphylococcus foodborne outbreaks
- Inadequate refrigeration
- Preparing foods far in advance
- Infected person practicing poor personal hygiene
- Inadequate cooking processing
- Holding food in a warming devices that promote growth
time required to destroy 90% of the organisms) is
dependent on the composition of the food
D-value
Staphylococcus is
Mesophilic
Organism produces seven Staphylococcus enterotoxins (SE), that affect enteric
nervous system – intestines
conditions increase toxin production
Aerobic
conditions little toxin is produced (only need 1
ug / 100 g of food)
Anaerobic
Foods commonly associated with Staphylococcal food poisoning fall into general categories
- Meat, meat products (cured meats)
- Mayo salads
- Creamed filled bakery products
- Dairy products
Symptoms Staphylococcal food poisoning
cramps, chills, diarrhea, sweating
Dehydration
Contamination of processed foods can be due to:
- Humans 50%
- Animals
- Environmental sources
