Lecture 3: Sources of Bacterial Pathogens

Question 1

T or F: Internal Tissues of healthy and fresh plants and animals are essentially sterile

Answer 1

True

Question 2

What are some sources pf pathogen contamination?

Answer 2

natural: surface of cut fruit, damaged tissues skin, feathers and gastrointestinal tract
external: air, soil, sewage, water, feed, human, ingredients, equipment, packages and insects

Question 3

sources of pathogen contamination in plants like fruits ang veg

Answer 3

Harbour microbes on their surface
This varies with growth conditions
Molds, yeasts, and non-pathogenic bacteria are present from the environment
Pathogens (particularly enterics) can be present if the soil was contaminated with raw sewage
Mexican harvester policy.

Question 4

How can the bacterial load be reduced in plants like fruits and veg?

Answer 4

Proper methods like using treated sewage, quick washing with clean water, and storage at low temperature can be used to reduce bacterial load
Workers must also follow good hygiene practices

Question 5

how can the microbial load be reduced for animals, birds, fish and shellfish?

Answer 5

Can minimize contamination using effective husbandry
Avoid overcrowding, use clean food and water
Test flocks for the presence of pathogens prior to slaughter
Careful removal of the GI tract
Harvest fish/ shellfish from clean water, and store in clean water

Question 6

Is air a source of pathogen contamination? why or why not

Answer 6

• yes
• microbes are present in dust and moisture droplets in the air.
• mostly air microbes are bacterial or mold spores, yeast, or some select gram-positive bacteria
• air surrounding highly contaminated areas such as sewage plants may contain pathogens.

Question 7

how can air contamination be reduced?

Answer 7

by removing potential sources, controlling dust particles in the air (using filtered air), using positive air pressure, reducing humidity, and installing UV lights

Question 8

why is sewage a source of pathogen contamination?

Answer 8

• used as fertilizer in crops and can contaminate food with microbes, particularly enteropathogenic bacteria and viruses.
• it is better not to use sewage as a fertilizer
• aqua culture operations can be contaminated by effluent if the harvest cities or waste water treatments plants. –> current BC oyster norovirus outbreak

Question 9

how can humans be a source of contamination for food?

Answer 9

can be a source of contamination by carrying environmental contamination into processing plants
-in addition sick workers can contaminate food products

Question 10

how did the japanese reduce their V parahaemolyticus problem? (4)

Answer 10

Regulation 1: Hygienic seawater. Seafood handlers were advised to use disinfected or artificial seawater, or potable water to wash and process shellfish and finfish
Regulation 2: Temperature control. The temperature for seafood during distribution and storage was recommended to be <4 °C, but was ultimately set at <10 °C
Regulation 3: V. parahaemolyticus levels in seafood. The microbiological standards of V. parahaemolyticus levels in seafood were set at <100 most probable number (MPN)/g for raw consumption, and non- detectable (ND) levels/25g for ready-to-eat boiled seafood
Regulation 4: Rapid consumption. Consumers were advised to consume seafood within 2 h after removal from the refrigerator. Restaurants were advised to serve seafood to consumers immediately after taking the seafood out of the refrigerator.