Microbiology of Foodborne Pathogens: Staphylococcus, Clostridium, Salmonella, and E. coli

staphylococcus aureus morphology

gram + coccus, facultative aerobe

where does staphylococcus aureus thrive?

high salt and low water content habitats

what are the 3 sources of staphylococcus aureus?

human nasal cavity, skin, skin sores

Staphylococcus aureus virulence factor

enterotoxin producer. it produces toxins that are heat stable and resistant to digestive proteases and stomach acid.

what foods are staphylococcus aureus found in?

cream-filled baked goods, poultry, meat, gravies, egg and meat salads, puddings, vegetables

how many cases of staphylococcal food infection in the US per year?

250,000

how are foods that cause staphylococcal food intoxification usually contaminated?

foods are usually contaminated during food preparation. contaminated foods are kept for several hours in the "danger zone"

onset time of symptoms for staphylococcal food intoxication

rapid onset: 1-8 hrs

what are the symptoms of staphylococcal food intoxication?

nausea, explosive vomiting, abdominal pain, diarrhea, headache, weakness

what symptom does NOT belong to staphylococcal food intoxication?

fever

duration of staphylococcal food intoxication

1-2 days

Clostridium botulinum morphology

gram + bacillus, spore former, strict anaerobe

sources of Clostridium botulinum

soil and water

what is Clostridium botulinum implicated in?

wound, infant, and food-borne botulism

what is the virulence factor of Clostridium botulinum?

it produces a heat labile (sensitive to heat), proteinaceous (made of protein), neurotoxin (exotoxin)

what foods is the Clostridium botulinum neurotoxin produced best in? and how are they destroyed

the toxin is produced best in high protein, low acid foods. the toxins are destroyed by high heat.

what are the food sources of Clostridium botulinum? (2)

nonacid home-canned vegetables like corn and beans, smoked an fresh fish

What kind of toxin is botulinum toxin?

neurotoxin

how are foods contaminated with botulinum toxin?

endospores may contaminate raw foods before harvest or slaughter. most foodborne cases occur from eating foods that are not cooked after processing.

when does infant botulism occur?

usually occurs in infants up to 2 months from raw honey

symptom onset of botulism

18-24 hours

what are the symptoms of botulism?

blurred vision, dizziness, cramps, sometimes vomiting, nausea, constipation, heart paralysis, difficulty in swallowing, speaking, and breathing

what is NOT a symptom of botulism?

fever

duration of botulism?

1-10 days to life

mortality rate of botulism

3-5%

what is the treatment of botulism?

antitoxin

how many cases of clostridium perfringens per year in the US?

1 million

how does clostridium perfringens occur in food?

spores are activated by cooking and germinate under anoxic conditions

what does clostridium perfringens do in the intestines?

large numbers of cells must be ingested. sporulation of vegetative cells occurs in the intestine triggering the production of the enterotoxin. l

how are vegetative clostridium perfringens cells killed?

cooking, extended refrigeration, and freezing

symptom onset of clostridium perfringens food infection

7-15 hours

symptoms of clostridium perfringens food infection

cramps, diarrhea, nausea

what symptoms are RARE in clostridium perfringens food infection

fever and vomiting

duration of clostridium perfringens food infection

12-24 hours

what foods can cause clostridium perfringens food infection?

meat, poultry, fish, dehydrated soups, sauces, foods cooked in bulk and then left at 20-40°C for short time periods

salmonella enterica morphology

gram - bacillus, facultative aerobe

sources of salmonella enterica

sewage (G.I. of birds and other animals)

foods that can have salmonella enterica

poultry, beef, pork, fruits, vegetables, eggs (custards, cakes, pies, eggnog), dairy products

how many cases of salmonellosis food infection per year?

1 million

what are the two classifications of salmonellosis food infection?

typhimurium and enteritidis

what happens with the cells in salmonellosis food infection

cells multiply and colonize in the small and large intestine, then invade and grow in phagocytic cells

infectious dose of salmonellosis food infection

usually 10^7-10^9 viable cells

what are the 3 virulence factors of salmonellosis food infection?

endotoxin, enterotoxins, and cytotoxins

what causes salmonellosis food infection?

fecal contamination of food via food handler or livestock. contaminated foods not heated before consumption.

symptom onset of salmonellosis food infection

8-48 hours

symptoms of salmonellosis food infection

headache, chills, vomiting, diarrhea, fever, enterocolitis (damage of GI tract)

duration of salmonellosis food infection

usually 2-5 days

what percentage of salmonellosis food infection victims become carriers for 4-8 weeks?

10-20%

morphology of pathogenic escherichia coli

gram -, facultative aerobe, coccobacillus

sources of pathogenic escherichia coli

sewage (GI tract of animals)

strains of pathogenic escherichia coli

ETEC, EPEC, EIEC, EHEC or STEC (bloody diarrhea)

foods that carry ETEC strain of pathogenic escherichia coli

contaminated drinking water

foods that carry EHEC strain of pathogenic escherichia coli

undercooked ground beef, unpasteruized dairy products and fruit juices, spinach, water

what is enterohemmorrhagic E. coli O157:H7 the leading cause of in children?

kidney failure

what is an infectious dose of enterohemmorrhagic E. coli O157:H7?

it is unknown

what kind of toxin does enterohemmorrhagic E. coli O157:H7 produce?

verotoxin

what two things can the verotoxin that enterohemmorrhagic E. coli O157:H7 produce lead to?

hemorrhagic colitis, hemolytic uremic syndrome

what is the enterohemmorrhagic E. coli O157:H7 bacteria destroyed by?

proper heat treatment

symptoms onset of enterohemmorrhagic E. coli O157:H7 food infection?

3-5 days

symptoms of enterohemmorrhagic E. coli O157:H7 food infection

bloody stools, intense abdominal pain, kidney failure, brain damage, death

what symptoms are RARE in enterohemmorrhagic E. coli O157:H7 food infection?

fever and vomiting

duration of enterohemmorrhagic E. coli O157:H7 food infection?

5-10 days

campylobacter morphology

gram -, motile, microaerophilic spiral shaped rods

sources of campylobacter

GI of animals (chickens, turkeys, hot dogs)

how is campylobacter destroyed?

pasteurizaiton, sensitive to air, freezing, and gastric acid

what are campylobacters termed as?

heat-tolerant campylobacters because they grow at 42°C, not at 25°C

how many cases of campylobacter food infection per year in the US?

>2 million

what two strains of campylobacter are most commonly linked to foodborne illness?

C. jejuni and C. fetus

what foods are involved in campylobacter food infection?

poultry, pork, raw clams, dairy

what does campylobacter do in the body?

multiplies in the small intestine and invades the epithelium

what does campylobacter food infection produce?

enterotoxin and cytoxin

what is an infectious dose of campylobacter?

500-10^4 bacteria (low)

symptom onset of campylobacter food infection

2-10 days

symptoms of campylobacter food infection

severe diarrhea, malaise, headaches, abdominal cramps, occasionally ulceration of ileum

what symptom of campylobacter food infection is RARE

vomiting

duration of campylobacter food infection?

1-10 days

Listeria monocytogenes morphology

gram +, faculatative aerobe, cocobacillus, psychrotolerant, acid-tolerant, salt-tolerant

sources of Listeria monocytogenes

soil, water, fecal material, vegetation, silage

food sources of Listeria monocytogenes

uncooked meat and vegetables, fruits, processed foods, unpasteurized milk and milk products

infectious dose of Listeria monocytogenes

<1000 in susceptible individuals

how many cases per year of listeriosis food infection?

less than 100, but it causes an estimated 20% of deaths from foodborne illness

symptoms onset of listeriosis food infection

few days to 2 months

symptoms of. listeriosis food infection

fever, muscle aches, nausea, diarrhea, headache, bacteremia, ,meningitis, confusion, loss of balance, miscarriage

duration of listeriosis food infection

5-10 days

who is most vulnerable for listeriosis food infection

pregnant women, the young and old, immuno-compromised individuals

what should people at risk for listeriosis food infection not eat?

soft cheeses, refrigerated smoked meats, deli meats, and undercooked hot dogs

what are most foodborn infections thought to be caused by?

viruses

incubation for other foodborne illnesses

12-48 hrs

what are responsible for the most mild foodborne infections in the US?

norovirus