Download Microbiology for Producers

Microbiology for
Producers
Microbial Hazards
Microbial hazards are the most common
cause of foodborne disease linked to fresh
fruits and vegetables.
Microbial contaminates include bacteria,
viruses and protozoan parasites.
Bacteria
Escherichia coli O157:H7 and Salmonella
are the bacteria most common to cause
foodborne illness outbreaks.
Viruses
Noroviruses are the
number one cause of
produce-related
disease.
Parasites
Cryptosporidium parvum
and Cyclospora
cayetanensis are the
protozoans causing
disease clearly linked to
consumption of fresh
produce or freshsqueezed juice.
Microbiology Lingo
Log Reduction
(log10CFU/g)
Percent
Control
1
90%
2
99%
3
99.9%
4
99.99%
5
99.999%
Examples of Harmful Bacteria
pg. 72
Bacteria
Produce
Salmonella species
Fecal
mainly birds and
reptiles
E. coli O157:H7
Fecal
mainly cattle, hogs
deer, sheep, goats
cantaloupe (90,91, 97, 00, 01,02,08), lettuce (06)
watermelon (91), tomatoes (98, 03, 04, 06,08),
bean sprouts(06), peppers (08), green onions (06),
alfalfa sprouts (96,09), carrots (06), cilantro (08)
cantaloupe (93), alfalfa sprouts (97,98),
un-pasteurized apple cider/juice (91,96),
lettuce (95, 96, 98, 99, 01, 06), cabbage-coleslaw (98)
spinach (06), radish sprouts (96)
Shigella species
Fecal – mainly human
parsley (98), cilantro (98), lettuce (83, 86, 94),
green onions (94)
Listeria monocytogenes
Natural in soil
cabbage-coleslaw (81, 83), potatoes (88), radish (88)
Examples of Harmful Viruses and Parasites
Viruses
•Hepatitis A virus
Produce
Fecal, mainly human
Green onions (scallions 03),
raspberries (90), strawberries
(97), lettuce (88)
•Norwalk-like virus
Raspberries (05), lettuce (02)
Fecal, mainly human
Parasites
•Cyclospora
Fecal, mainly human
•Cryptosporidium
Fecal, mainly human and
reptile
Raspberries (96, 97, 98),
basil (97), snow peas (04),
lettuce (97, 02)
Un-pasteurized apple cider (93,
03, 06), green onions (97)
What are the three most common
microbial causes of foodborne illness?
1. Generic E. coli, fecal
coli forms, Enterococci
2. E. coli O157:H7,
Salmonella, Listeria
monocytogenes
3. Bacteria, viruses,
protozoan parasites
4. Viruses, E. coli,
Salmonella
0%
1
0%
0%
2
3
0%
4
Escherichia coli O157:H7
• Frequently associated with leafy green outbreaks
• Found in the intestine of warm blooded animals
• > 200 types; most are harmless
• O157:H7 has the ability to decrease intracellular pH
allowing it to resist acid toxicity
•
•
•
•
•
•
•
•
Sources of E. coli O157:H7
People
Cattle
Goats
Sheep
Pigs
Elk
Deer
Insects
Animals of main concern as outlined
by CDC.
www.cdc.gov/nczved/divisions/dfbmd/diseases/ecoli_o157h7/
index.html
Prevalence of E. coli O157:H7
Prevalence of E. coli O157:H7
from past reports
Cattle
0-33.8%
Goats
0-33%
Sheep
0-31%
Pigs
0-14.9%
Elk
0-3.4%
Deer
0-2.4%
Horses
1 report
Varmints:
Coyotes-1
Possum-1
Rabbits
Raccoons
Skunks
Squirrels
0%, but
a few
examples
have been
reported;
such as
coyotes and
possums.
Survival of E. coli O157:H7
Survival of Pathogens
Animal
Survival
E. coli O157:H7
Bovine
Feces
56 days @ 72°F
49 days @ 99°F
Sheep Feces
21 months @ Ambient conditions
What is one unique characteristic of E.
coli O157:H7 that generic E. coli doesn’t
have?
1.
2.
3.
4.
An ability to resist acid
toxicity by decreasing
intracellular pH
An ability to reproduce
in temperatures over
100 degrees F
A resistance to chlorine
A preference to fresh
produce over other food
products
0%
1
0%
0%
2
3
0%
4
Spinach Outbreak 2006
•204 cases, 102 hospitalizations, 5 deaths, 33 cases
of Hemolytic Uremic Syndrome
•Covered 26 different states
• All animals have Escherichia coli (generic)
•Most animals with a grain diet have E. coli
O157:H7
•Only E. coli O157:H7 toxin causes this
•Hemolytic Uremic Syndrome (kidney failure)
Quickest Response to a Food Safety Problem
•>900 samples were collected
•4 ranches/fields were suspected
•2 state of the art operations were suspect
•7 cow patties positive for same strain
•1 slaughtered wild hog positive for same strain
•1 stream/ditch water positive for same strain
•13 bags of spinach positive for same strain (17 Total)
Source FDA
Quickest Response to a Food Safety Problem
•FDA notified of multi-state investigation on Sept. 13
•California Food Emergency Response Team (CalFERT)
dispatched Sept. 14
•Phone calls between FDA, CDHS, and three firms
began on Sept. 14
•Voluntary recalls began on Sept. 15
•Four ranches/fields provided product on Aug. 15
Source FDA
Salmonella
• Associated with a variety of commodities
• > 2,000 types
• Most recent outbreak was largest in produce
history with 1,442 ill people
• Can survive and even grow in acidic conditions
Sources of Salmonella
People
Rodents
– Rats
– Mice
– Etc.
Fowl
Snakes
Insects
Tend to seek refuge and nest in
trees, out buildings, storage barns,
brush lines etc.
Survival of Salmonella
Survival of Salmonella
in acidic Food Products
Product
pH
Tomato (tissue)
4.16-4.67
Orange (juice)
3.96-4.29
Watermelon (suspension)
5.5
Papaya (slices)
5.69
Jicama (slices)
5.97
In the Retail Food Store Sanitation Code of the U.S. Food and
Drug Administration, foods with a pH value of less than 4.6
are generally regarded as low risk in terms of food safety.
Prevalence and Survival of Salmonella
Prevalence of
Salmonella
on Cantaloupe
from past reports
Location
U.S.
Mexico
Amount
0.5-3.3%
0.3%
Survival of Pathogens
Animal
Survival
Salmonella
Bovine
Feces
184-332 days @
Ambient
conditions
Avian
Feces
28 months @
Ambient
conditions
1442 ill, with 286 hospitalizations and possibly 2 deaths
Produce distributor
positive sample
Mexico Farm
positive irrigation
water sample
Mexico Farm
positive sample
Shigella
• Humans are a natural
reservoir
• 4 Shigella species that
cause shigellosis
• 3rd most common
foodborne illness (2008)
• Fecal-oral transmission
route and low infectious
dose
• More common in
restaurant outbreaks
Cyclospora
• Person to person or direct fecal contamination
are unlikely
• 7-15 days for oocysts to mature and become
infective
• Most likely route of contamination is water
Cryptosporidium
• Person to person contamination is most
common
• Oocysts mature in human host
• 2003 – outbreak on apple cider,
manufacturer followed recommended GMPs,
but didn’t result in 5 log reduction when
using ozone treatment
Hepatitis A Virus (HAV)
• Usually spread when human fecal
matter is ingested from an
infected person
• Viruses can not multiply in food
• Most outbreaks are a result of
direct human contamination,
usually as a result of poor hygiene
• New testing procedures allow
viral sequences to be determined,
which can detect origin or source
- Ex. green onions in Mexico
(2003)
Noroviruses
•Leading cause of all
foodborne illness
•Increase in prevalence is
explained by
improvement in testing
methods
•Transmitted through a
fecal to oral route, but
simple hand washing
after using restrooms
could significantly reduce
outbreaks of this disease
Outbreaks from Produce
1990-2004
Pathogen
# of
Outbreaks
%
Norovirus
251
39%
Salmonella
120
19%
E. coli
48
8%
All other
220
34%
Total
639
100%
Leon, J.S., Jaykus, L.A., Moe, C.L. (2007)
Microbiology of fruits and vegetables.
Microbiologically Safe Foods (SantosGarcia J. ed.). John Wiley & Sons. New Jersey.
Data Source CSPI.
Fecal Pathogens
Pathogens of fecal origin tend to appear most
frequently in food borne illness outbreaks.
Common fecal pathogens that cause foodborne
illness:
•Cryptosporidium
•E. Coli O157:H7
•Hepatitis A virus
•Salmonella
•Norovirus
•Shigella
•Cyclospora
Recent studies have found which type
of virus to be a leading cause of
foodborne illness?
1.
2.
3.
4.
HAV
Salmonella
Norovirus
E. coli
0%
1
0%
0%
2
3
0%
4
Environmental Pathogens
•Listeria is found naturally in the soil
while E.coli and Salmonella are shed
from feces.
•E. coli O157:H7, Salmonella and Listeria
monocytogenes are the pathogens that
cause the most deaths.
•Once in the field these pathogens survive
and multiply under favorable conditions.
Importance of Listeria
• 20% of infected people die
Annual Food Related
Illness and Death (1999)
Source
Illness
Death
Salmonella
1.34
million
550
E. coli O157:H7
62,000
50
Listeria
monocytogenes
2,500
500
Listeria Survivability
Survival of
Pathogens
Listeria
monocytogenes
Surface
Soil
Pond
Water
8.7% to
51.4%
63 days
Soil does not seem to
support extensive Listeria
multiplication, but it’s
presence is probably due
to contamination by
decaying plant and fecal
matter.
Survivability of all Pathogens
A pathogens survivability depends on:
• Predation
• Competition
• Temperature
• UV radiation
•Inorganic ammonia
•Organic nutrients
•pH
•Water stress/osmotic potential
Where is Listeria naturally found?
1. Gastrointestinal
tract of ruminants
2. Water
3. Soil
4. Feral hog feces
0%
1
0%
0%
2
3
0%
4
Preharvest Aspects
• Prevention of contamination is paramount to
GAPs
 Log of signs or presence of animals of concern
 Log of preventative measures
 Log of corrective action
 Intervention is more costly than prevention
Postharvest Aspects
• Postharvest operations present greater
opportunities for contamination
• Good hygiene and hand washing are good lines
of defense in the field and packing shed
• Adequately designed tools, equipment and
surfaces are very important
• Outbreaks have an economic impact on not
only that company, but all companies
producing that commodity