Download File

Understanding Bacteria
Bacteria Everywhere
Food Safety and the Battle
with Bacteria
 The United States has one of the most
safest food supplies in world but there is
always room for improvement
 New 2011 statistics for foodbourne illness:
 48 million cases of foodbourne illness in the
U.S. 2011
 128,000 cases of hospitalization
 3,000 U.S. deaths due to foodbourne illness
Where do they come from?
 Bacteria are found everywhere and under
the right conditions they can multiple fast
 Each bacterium contains all the genetic
information needed to copy itself
 Bacteria multiple through binary fission, a
process in which the cells DNA doubles, the
cell splits, and two independent cells are
formed
 1 million bacteria can fit inside 1 square inch
 Single cell can become billions in one day!
Fascinating!!!
 Bacteria can multiply quickly-in fact, one cell
can double within 20 to 30 minutes
 It takes less than 10 E. Coli bacteria to make
you sick
 Electron microscope is used to view
bacteria-because it uses electrons instead of
visible light to produce magnified images-1
million times their normal size
Rapid Growth
 Is not usually a problem with good
bacteria…however, when it comes to
bad bacteria (a.k.a. pathogens) it is
bad news for the victim
 As pathogens multiple, some give off
harmful toxins or become infectious
 When pathogens enter the food and
multiple…we get sick
12 Most Unwanted Bacteria





Campylobacter jejuni
Clostridium
perfringens
Clostridium botulinum
Escherichia coli
0157:H7
Listeria
monocytogenes







Salmonella enteritidis
Salmonella
typhimurium
Shigella
Staphyloccus aureus
Vibrio cholerae
Vibrio vulnificus
Yersinia enterocolittica
Required Conditions for
Bacterial Growth
 Time/Temp
 Nutrients
 PH
 Moisture
Time/Temperature
 Time/Temperature-To minimize
bacterial growth in foods, it’s important
to keep food temperatures below 40ºF
or above 140ºF
 The level in between this temperature
range is known as the danger zone
Nutrients
 Bacteria need many of the same
nutrients as humans in order to thrive
(glucose, amino acids, vitamins,
minerals)
 Bacteria grow rapidly in high-protein
foods like meat, poultry, eggs, dairy,
and seafood
PH
 Microorganisms thrive in a ph range
above 4.6.
 That’s why acidic foods like vinegar
and citrus juices are not favorable for
pathogenic bacteria to grow; however,
they may survive
Moisture
 Most bacteria thrive in moist environments;
they don’t grow on dry foods.
 That’s why dry foods like cereals can safely
sit out at room temperature
 Note:If dry foods like dry cereal or spices
become contaminated from infected hands
or equipment, bacteria can survive on the
food and make people sick but they can’t
grow or multiple until the food is consumed
The 4 C’s of Food Safety
 Cook
 Clean
 Combating cross-contamination
 Chill
Cooking
Kills bacteria by breaking down
the cell walls and destroying
enzymes, which they need to
survive
Chilling
 Slows down the bacteria’s metabolism
thus slowing their growth. Not only can
bacteria grow to large numbers and
make people sick, but they can also
spread everywhere. That’s where
cleaning and combating crosscontamination come in
Cleaning
 Removes bacteria from hands and
surfaces
 Wash hands, surfaces and utensils
before, during and after handling foods
Combating CrossContamination
 Separate raw meat, poultry, and
fish/seafood from ready to eat foods
 Prevents bacteria from spreading from
one item to another
 Wash hands after handling all foods
and keep work surfaces (cut boards),
utensils clean after each use, otherwise
you are at risk of cross-contamination
Emerging Pathogens
 Not only can bacteria multiply fast, but they
can also mutate (adapt and evolve), a
process that results in changes to their
genetic code
 These changes happen very slowly and can
make the bacteria better able to survive
 They can change harmless bacteria into
harmful bacteria
 This fact often possess a new genetic
characteristic like antibiotic resistance
How Scientists Can Tell Good
Bacteria from Harmful Bacteria
 DNA-deoxyribonucleic acid is the
genetic blueprint for all living things
 DNA contains the information that
gives living things their traits or
characteristics
 In bacteria, the DNA molecule encodes
the information that enables bacteria to
grow, reproduce, and cause illness
DNA Fingerprints
 Scientists use DNA fingerprinting to identify
similar groups of bacteria
 DNA is treated so it exhibits its own special
pattern
 When there is an outbreak, scientists try to
determine the source of bacteria in foods by
examining the pathogens DNA fingerprintmatch to other samples in other words