EXAM 3 LECTURE 1: FOOD MICROBIOLOGY

salmonella

shigella

e. coli

camplyobacter

Common gram negative food borne bacteria

salmonella

- MEATS (POULTRY), EGGS, fish, shrimp, cream-filled deserts and unpasteurized milk

- symptoms occur within 24-72 hours

- nausea, vomiting, fever, diarrhea, abdominal cramps

- infective dose: as few as 15-20 cells

infants, elders, and people with impaired immune system

Severe cases of salmonella is more likely to affect what groups of people?

- bacteria travels to small intestines

- adhere to lining

- begins life cycle

(in severe cases)

- breaks down lining/wall

- get into bloodstream (can be deadly if not properly treated)

How does salmonella progress?

shigella

- daycare centers and/or nursing homes

- symptoms occur 1 - 2 days after exposure

- diarrhea (sometimes bloody), fever, abdominal pain

- tenesmus (painful sensation of needing to poop but bowels are empty)

e. coli

- cause of EHEC

- found in feces and can be picked up and grinded into hamburgers

- common in under cooked ground beef, unpasteurized milk, apple cider, sandwich meats, and contaminated water

camplobacter

- C. jejuni

- sensitive to oxygen, drying, freezing, salting and acid

- heat labile toxin (broken down)

- common in most animals, shellfish, and unpasteurized milk (ex: raw chicken)

- gram NEGATIVE microareophilic s-shaped rod

Camplyobacter

Which bacteria is common in cross contamination?

Cutting raw chicken on a cutting board and then using same cutting board/knife to cut vegetables

Explain cross contamination.

Invasive gastroenteritis

What can lead to Guillain-Barre syndrome?

camplyobacter

- abdominal cramps, diarrhea, headache, watery and sometimes bloody stools, fever

- onset: 2-3 days

- dose: 400-500 cells

- can become antibiotic resistant due to antibiotics in animal food (mass production of cows given antibiotics when not needed)

listeria

staphylococcus

clostridium

bacillus

Common gram positive food borne bacteria

listeria

- gram positive rods

- facultative anaerobes

- incubation between 3-70 days (challenge to track down)

Listeria monocytogenes

The most virulent foodborne pathogens

- 1,600 illnesses and 250 deaths in US alone annually

- soil

- dairy products (past. and unpast.)

- hot dogs and deli meats

- ready to eat foods can be contaminated through handling

Where is Listeria found?

slicing meats and not changing or cleaning the blade

How are deli meats contaminated with Listeria?

- gram positive

- beta hemolysis

- motile at 30 C

- catalase positive

- oxidase negative

Describe biochemical activity of Listeria monocytogenes.

- septicemia

- meningitis

- encephalitis

- cervical infections

- nausea, vomiting, diarrhea

What is the pathogenicity of Listeriosis?

staphlyococcus aureus

- gram positive

- caused by staph enterotoxin

- meat mixes (meat/chicken salads with mayo), milk, creams, puddings

- bacteria from wound or mouth/nose

- vomiting more than diarrhea

- 2-8 hours after eating

Clostridium perfringes and botulinum

What are two main types of Clostridium?

- forms spores

- gram positive rods

What are characteristics of Clostridium?

Clostridium perfringens

- common in nature

- rapid regeneration: 6.3 mins

- heat liable toxin

- has sub terminal spores to survive cooking

- abdominal cramps, watery diarrhea, nausea

- large dose: 10 to the 8th cells

- found in cooked meat and poultry AND GRAVY

Clostridium botulinum

- MOST DANGEROUS clostridium

- spores, widespread in soil

- contaminate vegetables/meats

- in canned foods that didn't have adequate sterilization

- spores survive and germinate in the anaerobic environment

honey because babies below 1 year cannot break down botulism

What causes infant botulism?

absorbed in gut

carried via blood to peripheral nerve synapses, blocks release of acetylcholine

Pathogenesis of clostridium botulism

bacillus cereus

- gram positive rod

- spore forming

- facultative anaerobe

- very widespread in nature

- found in rice, potatoes, casseroles

Columbus, Indiana

2 foodborne outbreaks at once

- bacillus cereus

- clostridium perfringes

buffet - improper temperature

sink - only 1 in the restroom

What is special about the Tex-Mex restaurant outbreak?

1. diarrheal illness (diarrheal)

2. vomiting illness (emetic)

What are the 2 distinct illnesses of B. cereus?

Lecithin

mannitol egg plates for B. cereus

what does it ferment?

Norovirus

most common in long-term care facility

- very easily passed on to others

- 1/15 Americans contract this

- more than 70,000 Americans are hospitalized

- 800 Americans die yearly

- come into contact via food, people, surfaces

- get sick 12-48 hours later (sick for 1-3 days) HIGHLY CONTAGIOUS

- 2 weeks later, still shedding viral particles

- temporarily immune but there are many strands

General timeline of Novovirus

dehydration, cramping, fever, nausea, vomiting, diarrhea

symptoms of Novovirus infection

Length of time between ingestion and symptoms first appearing

bacteria may be in weakened condition in the lab compared to initial outbreak

What are the challenges of food microbiology?

staph enterotoxin

symptoms occur 2-8 hours later

shigella

symptoms occur in 1-2 days

listeria

symptoms occur in 3-70days