animal 4-5

What are the two topics in Lectures 4–5?

Food-borne diseases and water-borne diseases

What is the main route of food-borne pathogen transmission?

Oral route

What affects food contamination?

Organism, reservoir, handling/processing, and cross-contamination

Which pathogens can have humans as a reservoir?

Norwalk-like virus, Rotavirus, Campylobacter, Shigella

Which pathogens can have animals as a reservoir?

Campylobacter, Salmonella, E. coli O157:H7, Listeria, Toxoplasma

Where can food become contaminated?

Farm/field, slaughter plant, processing, point of sale, home

What are the major Gram-negative groups listed?

Pseudomonads, Acetic Acid Bacteria, Neisseria/relatives, Enteric Bacteria, Vibrio/relatives, Rickettsias

What are Enteric bacteria?

A phylogenetic group within Gammaproteobacteria

What type of oxygen metabolism do Enteric bacteria have?

Facultative aerobic

What shape are Enteric bacteria?

Rods

Do Enteric bacteria form spores?

No

Can Enteric bacteria be motile or nonmotile?

Yes

What do Enteric bacteria ferment?

Sugars

What are Escherichia?

Universal inhabitants of the intestinal tract of humans and warm-blooded animals

What do Escherichia synthesize for the host?

Vitamins

Are some Escherichia strains pathogenic?

Yes

Which bacteria are closely related to Escherichia?

Salmonella and Shigella

What characterizes Salmonella immunologically?

Surface antigens

What are Salmonella serovars?

Serogroups/subtypes based on surface antigens

What is Proteus known for?

Rapid motility and swarming

What is Proteus a frequent cause of?

UTIs in humans

What are Vibrio group bacteria like?

Motile, straight or curved rods

Are Vibrio group bacteria facultative aerobes?

Yes

What do Vibrio group bacteria use for metabolism?

Fermentation

What are the best-known Vibrio group genera?

Vibrio, Aliivibrio, Photobacterium

Where are most Vibrio group bacteria found?

Aquatic environments

What are the major Gram-positive groups listed?

Firmicutes, Mollicutes, Actinobacteria

What are Firmicutes?

Nonsporulating and endospore-forming groups

What are Mollicutes?

Mycoplasmas

What are Actinobacteria examples?

Coryneform/Propionic Acid Bacteria, Mycobacterium, Streptomyces and relatives

What determines microbial growth and food spoilage largely?

Moisture

Which foods are more perishable?

Higher-moisture foods

What organisms spoil fresh foods?

Bacteria and fungi

How do spoilage organisms cause spoilage?

They access food and use its nutrients

Why does E. coli often contaminate meat?

It is found in animal digestive tracts

How does microbial food growth occur?

Normal exponential growth

When is food spoilage usually observable?

During the last few population doublings

What are food preservation methods?

Cold, pickling/acidity, drying/dehydration, heating, aseptic processing, chemical preservation, irradiation

What is food poisoning/intoxication?

Disease from eating food containing preformed microbial toxins

Do toxin-producing microbes have to grow in the host?

No

What is a food infection?

Eating pathogen-contaminated food followed by pathogen growth in the host

Can pathogenic microbes be present in fresh foods?

Yes

How can some pathogens be rapidly detected?

Molecular or immunological tests

What is an example of a rapidly detected food pathogen?

E. coli O157:H7

Where are U.S. foodborne outbreaks reported?

CDC

What can indicate a foodborne outbreak?

A cluster from one food source

What can cause widespread foodborne outbreaks?

A processing plant or distribution center

What food was associated with an E. coli O157:H7 outbreak?

Spinach

Why is E. coli O157:H7 well studied?

It can be quickly traced

What does CDC do for food safety?

Surveillance

What are FoodNet and PulseNet?

Foodborne disease surveillance systems

What does FDA regulate?

Domestic and imported food

What does USDA FSIS regulate?

Meat, eggs, and poultry

What agency is involved with marine food safety?

National Marine Fisheries Service

What is Whole Genome Sequencing used for in foodborne disease?

Tracking/identifying related pathogens

What are the major steps of microbial pathogenesis?

Entry/adherence, colonization/infection, invasion, exotoxins, endotoxins

What happens first in pathogenesis?

Exposure

What happens after exposure?

Adherence to skin or mucosa

What happens after adherence?

Invasion of epithelium

What happens after invasion?

Colonization and growth

What can virulence factors cause?

Toxicity or invasiveness

What can toxicity cause?

Local or systemic effects

What can invasiveness cause?

Spread to original or distant sites

What ultimately results from tissue damage?

Disease

What do invasion enzymes do?

Break down/alter host tissue or interfere with host defenses

What does hyaluronidase do?

Helps break/alter host tissue for nutrients

What does coagulase do?

Helps protect the pathogen from host defenses

What is important for pathogen growth during colonization?

Nutrients

Can pathogens grow locally or spread through the body?

Both

What are exotoxins?

Proteins released as a pathogen grows

What are the three categories of exotoxins?

Cytolytic toxins, AB toxins, superantigen toxins

What food poisonings are associated with Staphylococcus and Clostridium?

Staphylococcal and clostridial food poisoning

What causes Staphylococcus aureus food poisoning?

Heat-stable enterotoxins

Where can S. aureus grow?

Common foods

How quickly can S. aureus food poisoning cause gastroenteritis?

Within hours

How do S. aureus enterotoxins act?

As superantigens

What do S. aureus superantigens cause?

Large T-cell and inflammatory responses

What does Staphylococcus alpha toxin do?

Forms pores in membranes

What happens when alpha toxin forms pores?

Extracellular influx and cytoplasmic efflux

What are cytolytic toxins?

Toxins that degrade membranes and cause lysis/death

What do hemolysins lyse?

Red blood cells

What cells can alpha toxin kill?

Nucleated cells and erythrocytes

What is SEB?

Staphylococcal enterotoxin B

What is SEB's solubility?

Soluble in water

What type of toxin is SEB?

Superantigen

How temperature-resistant is SEB?

Very temperature resistant

Can SEB survive boiling?

Yes, for minutes

How long can freeze-dried SEB remain active?

One year

What is the incubation period for inhaled SEB?

1–6 hours

What symptoms can inhaled SEB cause?

Fever, chills, and myalgia

How high can fever from inhaled SEB reach?

103–106°F

How long can fever persist?

5 or more days

What severe respiratory symptoms can inhaled SEB cause?

Nonproductive cough, retrosternal pain, and shortness of breath

How long can severe cough last?

Up to 4 weeks

What can very high SEB exposure cause?

Shock and death

What is the incubation period for ingested SEB?

1–8 hours

What symptoms follow ingested SEB?

Nausea, vomiting, cramping, abdominal pain, diarrhea

How long does most ingested SEB illness last?

8–24 hours

How is SEB diagnosed?

Serum antibody response after exposure

When does a significant SEB antibody response occur?

2–4 weeks after exposure