Gram - pathogens matthews lecture 1

Question 1

what’s the difference between gram + and gram - bacteria?

Answer 1

Gram - bacteria produce spores

Question 2

What is a target spoilage number?

Answer 2

Amount of CFU/cm2 which causes spoilage of the food

Question 3

Number of food bourne pathogen cases are most prevalent in which time of year? Why?

Answer 3

Summer months because food bourne pathogens can survive longer outside of their animal hosts.

Question 4

Difference between gram - bac. and gram + bacteria structurally?

Answer 4

Gram - bacteria contain capsules, flagella, lipolysaccaride layers and pilli.

Question 5

When you think about ecoli O157 H7 what do these numbers represent? How are they used to diffrentiate between ecoli? Antibody assays?

Answer 5

O antigen-lipopolysaccaride
H antigen-flagella
Prevalance of attack of antibodies to a specific antigen lets you know which type of bacteria is present.

Question 6

Function of capsules (k antigen) in pathogenic bacteria?

Answer 6

Protects bacteria from dessication, sanitizer penetration and makes it sticky to adhere to surfaces.

Question 7

infection vs. intoxication and incubation period?

Answer 7

Intoxication-shorter

Infection-longer

Question 8

what are the char. of gram - bacteria

Answer 8

• .94 aw to grow
• Facultive anaerobes
• no 02
• O2

Question 9

Campylobacter jejuni
Resovoir-
Infects whom
symptoms
Prevention
outbreaks associated with
Infectious dose-
spread through

Answer 9

Resovoir-poultry
Infects- children under two (developing countries), older children and adults (developed countries)
prevention
Symptoms-paralysis
-improve hygiene
-competitive exclusion (what is this?)
-animal vaccines
-1000 or more cells

Question 10

Ecoli Shiga toxin

• resovior
• infects whom
• symptoms
• prevention
• mechanism of infection
• infectious dose-
• Spread through-

Answer 10

-found mainly on vegetables and lettuce etc.
-infects-can infect anyone?
-symptoms-bloody diareah and in some cases brain injury and kidney faliure
-prevention
-animal vaccination
-handle food properly when purchasing or preparing foods
-probiotics/competitive exclusion
-sanitation programs
-invades epilitheal cells and causes lesions»>bloody diareah
infectious dose- 100 or more cells

Question 11

Salmonella
-resovoir 
-infects whom 
-symptoms 
-prevention
outbreaks are associated with
How is it spread

Answer 11

Salmonella:

• resovoirs-amphibians, reptitles, cattle feces
• infects whom-older adults, children, cases are rare
• symptoms
• prevention-sanitation programs, scientific processes, wash hands etc.
• outbreaks-
• comingling of eggs and cross contamination between poultry
• infectious dose: varies based on the types of foods

Question 12

Why do we refrigerate salmonella and why does washing the outside surface not work?

Answer 12

-salmonella colonizes the ovaries of hens and are found inside the egg and can only be stopped through refrigeration. No antimicrobial added to the egg surface will help disinfect it.

Question 13

How does the FDA and USDA create plans to deal with foodbourne illness outbreaks resulting from pathogenic food microbes?

Answer 13

The FDA and USDA collect epidmeiological data that on out breaks that occur and use them to formulate plans on how to enforce regulations to control specific microbes in food. So far they have been successful as there are very few outbreaks that occur in foods.

Question 14

Species of Ecoli

Answer 14

1. Diareagenic
   - six subtypes
2. Pathogenic

Serotypes-Ecoli O157 is most popular in the use while in other countries other serotypes may be dominant.