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Foodborne pathogens It can be classified into three forms: foodborne intoxication

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Foodborne pathogens It can be classified into three forms: foodborne intoxication foodborne infection foodborne toxicoinfection. E.coli. Botulinum. Salmonella. Campylobacter. Listeria. Staphylococci. Food Pathogens www.textbookofbacteriology.net Todar's Online Textbook of Bacteriology. - PowerPoint PPT Presentation
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Page 1: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Foodborne pathogens

It can be classified into three forms:

foodborne intoxication

foodborne infection

foodborne toxicoinfection

Page 2: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Food Pathogens www.textbookofbacteriology.net Todar's Online Textbook of Bacteriology

Microrganisms that cause food borne infection or intoxication:

Salmonella

BotulinumE.coli

ListeriaCampylobacter

Staphylococci

Page 3: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 4: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Foodborne Intoxication

illness from microbial exotoxin microorganism does not cause the illness,

the toxin released by the microorganism does common exotoxin producing

microorganisms

Staphylococcus aureus

Clostridium botulinum

Page 5: Foodborne pathogens It can be classified into three forms: foodborne intoxication

INTOXICATION Ingestion of FOOD CONTAINING

TOXIN causes illness Microbes produce toxin while

growing in food Ingestion of the microbes themselves may be harmless

Page 6: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Food borne intoxication

some bacteria grow in food and produce a toxin within the food which is then consumed e.g. Bacillus cereus and Staphylococcus aureus. When the food is consumed viable cells of the bacteria do not need to be present.

Page 7: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Following ingestion, Toxins are absorbed through the gastrointestinal epithelial lining and cause local tissue damage and may induce inflammation resulting in diarrhea or vomiting.

In some cases, toxins are translocated to distant organs or tissues such as liver, kidney, peripheral, or central nervous system where they can cause damage.

Page 8: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Food Poisoning/intoxication

Page 9: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Staphylococcal Toxin-Mediated Diseases: Food Poisoning

Page 10: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Exotoxins

most exotoxins are grouped according to the tissues they adversely impact neurotoxins damage the nervous system entereotoxins upset the intestinal

system cytotoxins afflict their damage on many

different types of cells by disrupting cellular function of by lysing the cell

Page 11: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Staphylococcus aureus Intoxication by consumption of heat

stable, preformed toxin in food Symptoms

vomiting (“projectile”) nausea abdominal cramps and diarrhea 1-6 hours after eating

food contaminated with toxin

Bacteria killed by mild heat. Toxins are very heat stable.

Will grow with or without air; toxin not usually produced in acid food; bacteria are resistant to high salt (up to 15%)

Page 12: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria Causing Intoxications Staphylococcus aureus (“Staph”)

Reservoir: Common on human skin and in nasal cavity--therefore commonly a problem in foods that are handled a lot

Transmission: Must multiply in food to produce enough toxin to cause illness

Disease: Primarily causes vomiting Incubation period: Short; usually 2 - 4 hours The bacteria is killed by cooking, however the

toxin is not destroyed by normal cooking!

Page 13: Foodborne pathogens It can be classified into three forms: foodborne intoxication

St. aureus and food

Staph grows and divides in food and produces an enterotoxin

The Staph doesn’t cause food poisoning, the enterotoxin does

Enterotoxin is stable to heating at 100oC for 30 minutes.

Enterotoxin is resistant to degradation by stomach gastric acids

Page 14: Foodborne pathogens It can be classified into three forms: foodborne intoxication

St. aureus and food poisoning St. aureus causes gastro-enteritis Food poisoning is not caused by the

organism but by the toxin that the organism secretes

St. aureus food poisoning is the most common form of food poisoning in the US

Page 15: Foodborne pathogens It can be classified into three forms: foodborne intoxication

How did the chef get a staph infection?

Staph is often found on skin surfaces because they can tolerate the low moisture and high salt content of skin

Staph can easily spread from person to person via hand to hand contact

Staph can penetrate the deep tissues of skin damaged by

burnscutsinsect bitesskin diseases—acne, eczema

Page 16: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Normal Flora

the presence of normal flora cover potential adherence sites for

invading microorganism

Normal microflora : produce compounds toxic to other microorganisms

bacteria found on skin

Page 17: Foodborne pathogens It can be classified into three forms: foodborne intoxication

What happens when Staph enters a wound and how does this relate to food poisoning ? Localized staph infection leading to an

abscess boils=abscesses in the skincarbuncle=interconnected abscesses

Rupture of the abscess leads to the release of live bacteria and associated toxin

Page 18: Foodborne pathogens It can be classified into three forms: foodborne intoxication

How do abscesses and boils form? Chef cuts arm and Staph enters deeper

skin layer St. aureus is surrounded by a capsule

thick slime layer that prevents an immediate immune response

Bacteria multiply at the site surrounded by the capsule

St. aureus establishes intimate contact with skin cells via bacterial techoic acids and fibronectin skin cell receptors

Page 19: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Staph enterotoxin causes gastro-enteritis in two ways VOMITINGtoxin works on the vomiting

control center of the brain this leads to reversal of peristalsis and vomiting

DIARRHEAenterotoxin is a superantigen and elicits a strong immune response in the region where the toxin is most concentrated. Immune response causes a loss of brush borders in intestinal epithelial cells; these cells cannot absorb water from the gut.

Page 20: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Folliculitis manifests as superficial pustules or inflammatory nodules surrounding hair follicles.

Page 21: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Furuncles (boils) are tender nodules or pustules caused by staphylococcal infection. Carbuncles are clusters of furuncles that are subcutaneously connected.

Page 23: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Cutaneous Abscess

A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface.

Page 24: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Erysipelas is characterized by shiny, raised, indurated, and tender plaque-like lesions with distinct margins. It is most often caused by β-hemolytic streptococci and occurs most frequently on the legs and face.

Page 25: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Non-bullous impetigo is a superficial skin infection that manifests as clusters of vesicles or pustules that rupture and develop a honey-colored crust.

Bullous impetigo is a superficial skin infection that manifests as clusters of vesicles or pustules that enlarge rapidly to form bullae. The bullae burst and expose larger bases, which become covered with honey-colored varnish or crust.

Impetigo (Bullous)Impetigo (Non-Bullous)

Page 26: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Ecthyma gangrenosum is a bacterial skin infection (caused by Pseudomonas aeruginosa) that usually occurs in people with a compromised immune system.

Ecthyma is a skin infection similar to impetigo, but more deeply invasive. Usually caused by a streptococcus infection, ecthyma goes through the outer layer (epidermis) to the deeper layer (dermis) of skin, possibly causing scars.

Page 27: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Necrotising fasciitis

Page 28: Foodborne pathogens It can be classified into three forms: foodborne intoxication

• The action of cholera enterotoxin is shown in Figure 21.22.

Page 29: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 30: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 31: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clostridium botulinum

(anaerobic, intoxication) Potent, Heat labile Neurotoxin

A few nanograms of toxin can cause illness

180F for 10 minutes Spores are heat resistant High mortality rate Associated with inadequately

processed home canned food Widely distributed in nature

Page 32: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clostridium botulinum Associated foods

Low acid canned foods Sausages Meat products Canned vegetables Seafood

Almost any type of food that is not very acidic (pH > 4.6) can support growth and toxin production

Page 33: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Exotoxins exotoxins are highly specific exotoxins are among the most lethal

substances known to man 1 gram of the exotoxin produced from

Clostridium botulinum is capable of killing the entire population of the United States, close to 300 million people

the danger with exotoxins is not the ingestion of the bacterium, but the ingestion of the toxin

Clostricium botulinum

Page 34: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clostridium botulinum (“botulism”) Reservoir: Spores found in soil and water

(ocean/lakes) Transmission: Associated with improperly

canned foods and ground-harvested foods such as onions and garlic

Disease: Toxin causes paralysis Incubation period: ½ day to 3 days Spore is difficult to destroy, but botulinum

toxin CAN be destroyed by cooking (e.g., 176F for 10 min)

Page 35: Foodborne pathogens It can be classified into three forms: foodborne intoxication

• Botulinum toxin consists of seven related toxins that are the most potent biological toxins known (Figure 21.20).

Page 36: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Botulism (C. botulinum):

The most potent toxin known; few cases but high mortality (25%); destroyed by 10 min in 80 oC

paralysis of muscles Common in soil and water How? Improper canning

spore germination toxin production canned food used without cooking disease

Page 37: Foodborne pathogens It can be classified into three forms: foodborne intoxication

All four types of botulism result in symmetric descending flaccid paralysis of motor and autonomic nerves always beginning with the cranial nerves. These symptoms are preceded by constipation in cases of infant botulism.

Symptoms include: Double or blurred vision Drooping eyelids Dry mouth Difficulty Swallowing Muscle weakness

Page 38: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Prevention

Proper food preparation is one of the most effective ways to limit the risk of exposure to botulism toxin.

Boiling food or water for ten minutes can eliminate some strains of Clostridium botulinum as well as neutralize the toxin as well. However, this will not assure 100% elimination.

Limiting growth of Clostridium botulinum and the production of botulism toxin is an alternative to their outright destruction.

Page 39: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Temperature, pH, food preservatives, and competing microorganisms are among the factors that influence the rate and degree of Clostridium botulinum growth.

Growth of most strains of Clostridium botulinum will not occur below 10 or above 50 degrees Celsius.

Page 40: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clostridium botulinum will not grow in media with pH values lower than about 5.

Food preservatives such as nitrite, sorbic acid, parabens, phenolic antioxidants, polyphosphates, and ascorbates inhibit the growth of the microorganism.

Page 41: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clostridium botulinum will not grow in media with pH values lower than about 5.

Food preservatives such as nitrite, sorbic acid, parabens, phenolic antioxidants, polyphosphates, and ascorbates inhibit the growth of the microorganism.

Page 42: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Lactic acid bacteria including Lactobacillus, Pediococcus, and Pactococcus can inhibit the growth of Clostridium botulinum by increasing the acidity of the medium.

While the cause of roughly 85% of infant botulism cases is unknown, in up to 15% of infant botulism cases the causes was ingestion of honey. Infants younger than one year old should not be fed honey.

Page 43: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Avoiding Exposure

Avoid home-processed foods if at all possible, especially those with a low salt and acid content.

Botulism toxin is destroyed at a temperature of 176 F, thus if you must eat home-processed foods, boil them for 10 minutes before eating if at all possible.

If canning vegetables, use a pressure cooker, as it will kill any spores because it can reach temperatures above boiling.

Page 44: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Foodborne Infection

requires consumption of microorganism symptomatic about 1 day following

ingestion of contaminated food common foodborne infecting

microorganisms Salmonella

poultry product infections Escherichia coli 0157:H7

undercooked hamburger

Campylobacter Salmonella

Page 45: Foodborne pathogens It can be classified into three forms: foodborne intoxication

food borne infectionInfections occur when pathogens are ingested via contaminated food and the bacteria is established in the body

usually growing inside the intestinal tract and irritating intestines.

The infection may involve subsequent growth in other tissues

Page 46: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Direct contacte.g., coughing, sneezing, body contact

Indirect contactvehicles (e.g., soil, water, food)

Page 47: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Adherence structures:Structures such as such as pili and fimbriae

and specialized adhesion molecules on bacterium’s cell surface bind to

complementary receptor sites on host cell surface

Colonization:

Colonization is the establishment of a site of microbial reproduction on or within host

does not necessarily result in tissue invasion or damage

Page 48: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Principles of Infectious Disease

virulence factors are substances or features of a microorganism that help it infect and cause disease

they may include ability to adhere ability to overcome host defense ability to evade host defense

Page 49: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Factors:number of organisms presentthe degree of virulence of pathogen

virulence factorse.g., capsules, pili, toxins

host’s defenses or degree of resistance

Page 50: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 51: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Attachment

Page 52: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Penetration into the Host Cell

Figure 15.2

Page 53: Foodborne pathogens It can be classified into three forms: foodborne intoxication

• Pathogen growth on the surface of a host, often on the mucous membranes, may result in infection and disease

Page 54: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 55: Foodborne pathogens It can be classified into three forms: foodborne intoxication

E. coli in Small Intestine

Page 56: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 57: Foodborne pathogens It can be classified into three forms: foodborne intoxication

• A pathogen must gain access to nutrients and appropriate growth conditions before colonization and growth in substantial numbers in host tissue can occur. Organisms may grow locally at the site of invasion or may spread through the body.

Page 58: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Shigellosis Pathogenesis S. dysenteriae

Rarely encountered in United States

Produces potent A-B toxin Shiga Toxin Acts much like

cholera toxin Toxin associated

with fatal hemolytic uremic syndrome

Page 59: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Helicobacter pylori Gastritis Pathogenesis

Bacteria survive extreme acidity of the stomach Able to neutralize

environment

Organism uses flagella to corkscrew through mucosal lining

Inflammatory response begins

– Mucus production decreases

• Without mucus stomach lining not protected from acidic environment

– Infection persists for years

• Possibly for a life time

Page 60: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Mechanisms of Pathogenesis

colonization of host surface, then toxin production invading pathogen is able to grow to high

numbers on host surfaces such as the respiratory and intestinal tract

they then produce a toxin that is damaging to the cells

organisms that use this mechanism include Vibrio cholerae, which causes cholera or Corynebacterium diphtheriae, which causes diphtheria

Page 61: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Mechanisms of Pathogenesis

invasion of host tissue breaching body’s barriers then multiplies in

the body’s tissues these organisms have mechanisms that

allow them to avoid macrophage destruction some are also capable of avoiding detection

by antibodies organisms that use this mechanism include

Mycobacterium tuberculosis, causative agent for tuberculosis, and Yersinia pestis, causative agent for plaque

Page 62: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Mechanisms of Pathogenesis

invasion of tissue, then toxin production breach the body’s barriers, then make toxins in addition to invasion, these organisms also

make toxins organisms that use this mechanism include

Shigella dysenteriae and Streptococcus pyogenes

Page 63: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Mechanisms of Pathogenesis in order to cause disease

microorganisms need to be able to adhere and colonize host tissue avoid the innate defenses avoid the adapted defenses cause damage related to the disease

Page 64: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Adherence

to establish disease the causative agent needs to Adhere

many bacteria have adhesions, generally found on the pili

Page 65: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Colonization

causative agent needs to multiply in order to colonize

to multiply, they must compete successfully with the normal flora for space and nutrients toxins that may be produced by the normal

flora must be overcome

Page 66: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 67: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Following ingestion, Toxins are absorbed through the gastrointestinal epithelial lining and cause local tissue damage and may induce inflammation resulting in diarrhea or vomiting.

In some cases, toxins are translocated to distant organs or tissues such as liver, kidney, peripheral, or central nervous system where they can cause damage.

Page 68: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Adhesions/ligands bind to receptors on host cells so won’t get flushed off.

Mechanisms to adhere and avoid host defenses: Glycocalyx Streptococcus mutans

Dextran (plaque) Waxes Mycobacteria Fimbriae Escherichia coli M protein Streptococcus

pyogenes Tapered end w/ hooks Treponema pallidum

Adherence

Page 69: Foodborne pathogens It can be classified into three forms: foodborne intoxication

CapsulesPrevent phagocytosis and help with attachment

(adherence) Streptococcus

pneumoniae Klebsiella pneumoniae Haemophilus influenzae Bacillus anthracis Streptococcus mutans Yersinia pestis

Page 70: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Many pathogens secrete enzymes that contribute to their pathogenicity: Increase virulence by use of enzymes And avoid phagocytosis

Coagulase Coagulate blood - wall off from host make boil

Kinases Digest fibrin clot - allow spreading

streptokinase and staphylolinase

Hyaluronidase Hydrolyses hyaluronic acid connective tissue

Collagenase Hydrolyzes collagen IgA proteases Destroy IgA antibodies Hemolysins lyse RBC’s

Enzymes to help penetration

Page 71: Foodborne pathogens It can be classified into three forms: foodborne intoxication

HemolysinsAlpha Hemolytic Streptococci

- secrete hemolysins that cause the incomplete lysis or RBC’s

Beta Hemolytic Streptococci

- secrete hemolysins that cause the complete lysis of RBC’s

Page 72: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Leukocidins

1. Kills WBC’s which prevents phagocytosis 2. Releases & ruptures lysosomes

lysosomes - contain powerful hydrolytic enzymes which then cause more tissue damage

Page 73: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Mechanisms of Pathogenicity

Figure 15.9

Page 74: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria Causing Infections

Salmonella spp. (non-typhoid) Most common cause of bacterial foodborne

disease using passive surveillance Reservoir: many food-producing animals Transmission: Associated with undercooked

meats (especially poultry) eggs, raw milk, and contaminated produce

Disease: Diarrhea and systemic infections Incubation period: ½ day - 1½ days

Page 75: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis

Causative Agent– Salmonella species

Motile Gram negative Enterobacteria

– Salmonella subdivided into over 2,400 serotypes

• Salmonella typhimurium and Salmonella enteritidis most common serotypes in United States

Page 76: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - mode of transmission

ingestion of raw, undercooked, or contaminated food meat, milk, eggs, produce

fecal-oral transmission contact with pets (especially infants) foods contaminated by infected food handler

outbreaks usually traced to food items

Page 77: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - disease frequency

incidence highest in infants and young children

estimated 5 million cases annually (US) up to 80% are sporadic cases large outbreaks in hospitals, restaurants,

institutions are common

largest outbreak in US (25,000 cases) resulted from a nonchlorinated municipal water supply

Page 78: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - disease frequency

proportion of reported cases due to S. enteriditis has increased from 5% in 1976 to 26% in 1994

report in J of Infectious Diseases (1994) - 82% of outbreaks due to S. enteriditis between 1985-1991 were traced to contaminated shell eggs

Page 79: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - disease frequency

case fatality rate <1% for most forms of salmonellosis 15% with S. dublin reported in elderly up to 4% with S. enteriditis (nursing homes,

hospital associated outbreaks with most being elderly)

Page 80: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonella Epidemiology

Etiologic Agent: Gram-negative bacteria in the family

Enterobacteriaciae. Currently, there are more than 2,460

serotypes.

Reservoir: Domesticated and wild animals, including

poultry, swine, cattle, rodents, dogs, cats, birds (including pet ducks and chicks), reptiles (including iguanas, snakes, and turtles).

Page 81: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis:

Gram negative enteric bacterium; all strains are pathogenic; transmission is from sources (eggs, meats) and by food handlers

Colonization of of intestinal epithelium

• Two diseases:

– Enterocolitis (most commonly by S. typhimurium): 105 - 108 viable cells; disease onset within 8 - 48 hrs; headaches, chills, vomiting, diarrhea and fever (2-3 days); continuous shading of organism for months/years (Typhoid Mary);

– Typhoid fever (S. typhi): Septicemia leading to high fever that can last for several weeks; mortality is 15% if untreated; antibiotics

• Prevention: Cooked food (70 oC for 10 min); monitor for carrier state among food handlers

Page 82: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Host-Parasite Relationships Fecal-oral transmission via

contaminated food or water Sources - milk & other dairy products,

raw eggs, dried or frozen eggs, meats, meat products, poultry, roast beef, corned beef, shellfish and undercooked whitefish, animal dyes, dried cocoanut

Origin - many animals are naturally infected with various Salmonellae (especially poultry)

Page 83: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Cont.

These can be found in tissues, eggs, and excreta

Household pets - turtles, dogs, & cats can also transmit these bacteria

Human carriers, especially food handlers Typhoid Mary

Page 84: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis

Pathogenesis Bacteria sensitive to

stomach acid Large number

required for infection Bacteria adhere to

receptors on epithelial cells of lower small intestine Cells take up bacteria

through phagocytosis Bacteria multiply

within phagosome discharged through exocytosis

Inflammatory response increases fluid secretion resulting in diarrhea

• Pathogenesis– Some strains of Salmonella typhi

are not easily eliminated• Organisms cross membrane and resist

killing by macrophages– Bacteria multiply within macrophages then

carried to bloodstream

• Organisms are released when macrophages die and invade tissues

– Can result in abscess, septicemia, and shock

Page 85: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis

Epidemiology Bacteria can survive

long periods in the environment

Children are commonly infected Generally by household

pets such as turtles, iguanas, and baby chicks

Most cases have an animal source

Enteric fevers, such as those caused by Salmonella typhi are generally the exception

“Typhoid Mary” notorious carrier Caused at least 53

cases over 15 years

• Prevention and Treatment

– Control depends on reporting cases and tracing source of outbreak

– Adequate cooking kills bacterium

– Vaccine available for prevention of typhoid fever

• Vaccine 50% to 75% effective

– Surgical removal of gallbladder eliminates carrier state

Mary Mallon

Page 86: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Typhoid Mary

Human carrier (and reservoir) of Salmonella typhi

Page 87: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonella enterica serovars Infect domestic animals Eggs and contaminated

meat One of the most

prevalent causes of food-borne illnesses

Transmission dose as few as 10 organisms

Attachment is key virulence factor

Page 88: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonella enterica serovars. Gram negative bacillus

Classification based on serology and phage susceptibility assays

Page 89: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Host Factors

Very important in intestinal infections Gastric pH, luminar wall sheath,

intestinal mobility Local immune factors, normal flora Intrinsic characteristics of pathogens Salmonellae = 105 organisms to cause

infect. Shigellae = 180 – 200 orgs. to cause

infect. ETEC = 106 - 107 orgs. to cause infect. Vibrios = 108 orgs.

Page 90: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis Sources

Raw poultry and eggs Raw milk Raw beef Unwashed fruit, alfalfa sprouts Reptile pets: Snakes, turtles, lizards

Signs Onset: 12-72 hours Diarrhea, fever, cramps Duration: 4-7 days

Page 91: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Clinical description of non-typhoidal Salmonella Other Symptoms May Include:

Fever Abdominal cramping Nausea Vomiting Chills Systemic symptoms – headache, myalgias,

etc.

Diarrhea usually lasts 3 to 7 days Mean carriage of Salmonella strains in

the stool can last 4 - 5 weeks after resolution of acute symptoms.

Page 92: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonella Epidemiology

Incubation Period: 6 - 72 hours, usually 12 - 36 hours

Infectious Period: As long as bacilli appear in the stool during

illness and usually several days to several weeks thereafter.

Prolonged shedding is more prominent in children <5 years of age.

Approximately 1% of patients become chronic carriers and continue to excrete organisms for more than 1 year.

Page 93: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonella Epidemiology

Mode of Transmission Transmitted through the ingestion of

food and water contaminated with human or animal waste.

Contaminated raw vegetables or fruits have also been implicated.

Fecal-oral route is important, especially from persons who have diarrhea or who are incontinent.

Page 94: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 95: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli

gram-negative rod-shaped bacteria hundreds of strains most strains are harmless, normal

intestinal flora of healthy humans and animals

occurrence: ubiquitous, worldwide distribution

Page 96: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Categories of Escherichia coli causing diarrhea

enterohemorrhagic (EHEC - hemorrhagic colitis; O157:H7)

enterotoxigenic (ETEC- traveler’s diarrhea)

enteroinvasive (EIEC - dysentery-like) enteropathogenic (EPEC - infant

diarrhea) enteroaggregative (infant d. in

underdeveloped countries) diffuse-adherence (pediatric diarrhea)

Page 97: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

first recognized in 1982 outbreak of hemorrhagic diarrhea traced to hamburgers (fast food chain)

estimated 10,000 to 20,000 cases/yr in the US

outbreaks have been associated with other foods such as leaf lettuce, cider, contaminated water

Page 98: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

“O” and “H” designation refer to cell surface antigen markers that are used to distinguish serotypes

Other serotypes of enterohemorrhagic strains may also be implicated (O26:H11; O111:H8; O104:H21)

does not grow well or at all at 44-45ºC

Page 99: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

syndrome caused by potent cytotoxins: verotoxins 1 and 2 (Shiga-like toxins I and II because resemble toxins of Shigella dysenteriae)

may also produce hemolytic-uremic syndrome

although recognized and intensively studied for 15 years, still do not know best method of treatment nor how animals become infected

Page 100: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Epidemiological features

Reservoir:

cattle especially young dairy cattle

wild ruminants - deer (?)

humans

Page 101: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Epidemiological features

Transmission: ingestion of contaminated foods

usually inadequately cooked beef (especially ground beef) raw milk other foods by cross-contamination--lettuce, apple cider,

apple juice

person-person (families, child care facilities, institutions)

waterborne (swimming in crowded areas, drinking water)

Page 102: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Epidemiological features

Incubation period: relatively long, ranging from 3-8 days

Period of communicability: <1 week in adults may be up to three weeks in children prolonged carriers uncommon

Page 103: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Epidemiological features

Susceptibility and resistance

very low infectious dose

old-age appears to be a risk factor

children < 5 years of age are at greatest risk of developing hemolytic-uremic syndrome

Page 104: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Clinical features

diarrhea ranging from mild, non-bloody to virtually

straight bloody stool, abdominal cramping

fever is infrequent

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Escherichia coli O157:H7

Clinical features

Hemolytic-uremia syndrome

more common in children may occur in up to 10% of cases characterized by:

hemolytic anemia thrombocytopenia renal failure (common cause of renal failure in

children)

Page 106: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Clinical features

Thrombotic thrombocytopenic purpura (TTP) in elderly

Case fatality rate: 3-5% (up to 50% in elderly with TTP)

Page 107: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Control methods

Preventive measures to reduce incidence

slaughterhouse management to minimize contamination of meat by intestinal contents

pasteurization of milk and dairy products irradiate beef, especially ground beef

Page 108: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Control methods

preventive measures to reduce incidence adequately cook meat to a temp of 155°F

(68°C) ‘pink all gone’ does not mean necessarily safe -

cooking with meat thermometer is recommended protect, purify, chlorinate public water

supplies for drinking chlorination of swimming pools adequate hygiene in day-care facilities

Page 109: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Control methods

control of patient and immediate environment report to health department (mandatory in many

states) isolation: because of extremely small infective

dose, patients should not be allowed to handle food or provide child/patient care until 2 negative samples are obtained

disinfection contacts with diarrhea should be handled as if

infected (no food handling, no patient care or child contact) until two negative fecal samples are obtained

Page 110: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Escherichia coli O157:H7

Control methods treatment

fluid/electrolyte replacement

antibiotic treatment uncertain; TMP-SMX may lead to hemolytic-uremia syndrome

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Page 112: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Causative organisms: primarily S. enteriditis, typhimurium in U.S.

numerous serotypes, many are pathogenic to both animals and man

of the ~2,000 serotypes known, only ~200 recognized in the U.S.

discovered in 1880, genus named for American scientist Salmon in honor of his extensive work

Page 113: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Microbiological features and identification gram-negative rod-shaped bacteria motile (non-motile forms are S. gallinarium,

pullorum) heat labile growth prevented at <7º C for most serotypes non-spore forming, but can survive for long

periods in foods and other substrates can survive for long periods in foods with low

aw (water activity) such as chocolate, peanut butter, black pepper)

Page 114: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - reservoir

ubiquitous found in a wide range of animals, particularly

poultry, swine, cattle, pets (iguanas, turtles, terrapins, tortoises, chicks, dogs, cats), humans

chronic carriers common in animals and birds, less so in humans

S. enteriditis infects ovaries of healthy appearing hens, thereby contaminating eggs in oviduct before shell is formed

Page 115: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Epidemiology - reservoir

S. typhi, paratyphi - man only S. typhimurium - animals, particularly food

animals S. enteriditis - animals, particularly food

animals S. dublin - cattle S. choleraesuis - swine S. gallinarum, pullorum - poultry S. arizonae - animals, reptiles

Page 116: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Salmonellosis

Symptoms Generally characterized by

Diarrhea Abdominal pain Nausea Vomiting Fever

Symptoms vary depending on virulence of strain and number of infecting organisms

Symptoms are generally short-lived and mild

Page 117: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Selected outbreaks in US

1985 - 16,000 cases in 6 states low fat and whole milk from a Chicago dairy pasteurization process changed, resulting in

contamination of pasteurized milk with raw milk persons on antibiotic therapy more likely to be

affected

1984 - ~2700 passengers affected on 29 flights caused by S. enteriditis strongly associated with food in First Class

section only

Page 118: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Clinical features

generally, salmonellosis is a milder disease than typhoid/paratyphoid

acute disease nausea, vomiting, cramping, diarrhea,

fever, headache more severe, even life-threatening

disease can occur in infants, elderly, immunocompromised

Page 119: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Clinical features

chronic disease small percentage of cases develop Reiter’s

syndrome arthritic pain, irritation of eyes, painful

urination can last for months to years, leading to chronic

arthritis refractive to treatment antibiotic therapy does not seem to prevent

development of this serious sequela to acute salmonella infection

Page 120: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Clinical features incubation period: variable - 12 to 72

hours illness generally lasts 4-7 days disease is caused by penetration and

passage of organisms from gut lumen into epithelium; enterotoxin production (?)

infective dose: as few as 15-20 cells depending on strain (4

serotypes ingested in vehicles that buffer gastric acids)

normally >102-3

Page 121: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Diagnosis serological identification of culture isolated

from stool

Food analysis developed for many foods conventional methods - 5 days for

presumptive results rapid methods require only 2 days

Page 122: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Prevention and control

FDA: ‘farm-to-table’ actions to reduce food safety risks associated with shell eggsfarm

slaughter processing

retail

consumer

1 in 20,000 eggs produced annually contain S. enteriditis

Page 123: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Prevention and control

FDA/FSIS pending proposals 38 states require refrigeration at retail level voluntary quality assurance programs for egg

producers cleaning/disinfecting hen houses rodent control proper egg washing refrigeration between transport and storage biosecurity measures monitoring chick mortality use of SE free chicks and pullets

Page 124: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Control processing - control of factors such as pH,

moisture, presence of preservatives should me assessed at all stages using systematic approach (HACCP)through transit, storage, foodservice, and retail levels

storage at low temperatures - most serotypes fail to grow below 7ºC

retail handwashing avoid food preparation by workers with

diarrhea thoroughly cook all poulty, pork, meat, egg

dishes strict sanitation practices in kitchen, including

rodent and insect control

Page 125: Foodborne pathogens It can be classified into three forms: foodborne intoxication

SALMONELLOSIS

Control consumer control

FDA Recommendations avoid consumption of raw eggs avoid cross-contamination - clean utensils,

disinfect surfaces, proper hygiene, separate cutting surfaces for raw and cooked meats and vegetables

thoroughly cooking meat, poultry, eggs (71ºC) do not freeze eggs in shell store cooked eggs in refrigerator, discard after 1

week recognize risk in pets (chicks, ducklings, and

reptiles)--not recommended for small children

Page 126: Foodborne pathogens It can be classified into three forms: foodborne intoxication

LISTERIOSIS

Causative organism: Listeria monocytogenes

common inhabitant of intestine, soil, silage, other environmental sources

most are pathogenic to some degree not recognized as a food-borne pathogen

until the 1980’s

Page 127: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Microbiological features and identification

gram-positive rod-shaped motile, flagellated non spore-forming will grow at pH 4.4 - 9.6 will grow in high salt concentrations

(>10%)

Page 128: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Microbiological features and identification

resistant to heat, freezing, drying able to grow at temperatures as high

as 50ºC and as low as 3ºC (psychotrophic - able to grow at refrigerator temperatures)

freezing has little detrimental effect on the organism

Page 129: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Microbiological features and identification

aerobic, microaerophillic growth on simple media (blood, trypticase

soy agar) or selective media (McBride’s agar)

cold-enrichment techniques - too time consuming once recognized as a food pathogen now have faster methods - FDA (dairy

products); USDA (meat products)

Page 130: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Reservoir ubiquitous primary reservoir is soil, silage,

environment also present in intestinal tract of animals

and humans; asymptomatic carriers common (up to 10%)

seasonal use of silage followed by increase in number of listeriosis cases in livestock

Page 131: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Susceptibility and resistance fetuses, newborns are highly

susceptible older aged, immunocompromised

individuals acquired immunity unlikely

Page 132: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Mode of transmission foodborne - outbreaks associated with

ingestion of raw or contaminated food milk (raw and supposedly

pasteurized), cheeses (particularly soft-ripened), ice cream, raw vegetables, fermented raw-meat sausage, raw and cooked poultry, raw meat, raw and smoked fish

Page 133: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Mode of transmission direct contact neonatal

transmitted in utero during passage through infected

birth canal contaminated equipment in

nurseries

Page 134: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Frequency of disease in US - ~1,850 cases annually case fatality rate: 425 deaths annually

30% in newborn infants up to 50% when onset within first 4

days nonpregnant - recent epidemic 35%

(63% in >60 yrs of age)

Page 135: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features

Risk factors pregnancy (20 times more likely to

get listeriosis); 33% of cases occur during pregnancy

newborns - more likely to suffer serious effects

immunocompromised (AIDS, CA, diabetes, renal disease, elderly)

Page 136: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Epidemiological features source of infection in selected outbreaks

Maritime Provinces (Canada) - coleslaw made from cabbage fertilized with sheep manure; 28% CFR

California (1985) - Mexican-style cheese, numerous stillbirths; 142 cases, 33% CFR; FDA now monitors all domestic and imported cheeses

many cases are sporadic, now thought to be foodborne, associated with soft cheese (Brie, Camembert, etc.)

jellied pork tongue - cause of 279 cases, 63 deaths, 22 abortions in France in 1992

Page 137: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Clinical features Target population

pregnant women/fetus Cancer patients immunocompromised (AIDS, steroid therapy,

graft suppression therapy) elderly healthy individuals - low risk

antacids and H2 blockers may predispose to infection

outbreak among healthy individuals in Switzerland involving heavily contaminated cheese

Page 138: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Clinical features incubation period: variable - 3 to 70 days signs and symptoms:

flu-like symptoms septicemia meningitis or meningoencephalitis encephalitis intrauterine or cervical infections spontaneous abortion (2nd or 3rd trimester) gastrointestinal symptoms (nausea, vomiting,

diarrhea) onset time varies: few days to 3 weeks in

serious disease, > 12 hours in more mild forms

Page 139: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Clinical features infective dose varies with strain; foodborne

disease occurs with less than 1,000 organisms in susceptible individuals (immunocompromised, elderly)

invades monocytes, macrophages, PMN leukocytes, hence name and pathogenesis (transplacental and access to brain tissue)

“circling disease” and abortions in cattle, sheep, and goats

Page 140: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Diagnosis isolation from CSF, blood, amniotic fluid,

placenta, gastric washings growth on routine media serology unreliable

Food analysis FDA method (1990) requires 5-7 days for

identification use of specific DNA probes should afford faster

and less complicated confirmation of isolates

Page 141: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control Prevention of listeriosis begins on the farm

and continues through processing and handling by the consumer

On the farm: silage production controlled to achieve

rapid acidification (pH <4.0) storage of milk at low temperatures

(<5ºC) until shipping

Page 142: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control

Processing control of factors such as pH, moisture,

presence of preservatives should me assessed at all stages using systematic approach (HACCP)

measures to prevent contamination through transit, storage, foodservice, and retail levels

Page 143: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control

Three major objectives of processing control minimize growth and multiplication of

organism in raw foods, particularly before and during processing

use of appropriate products to assure destruction of organism

minimize risk of recontamination of ready-to-eat products

Page 144: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control

Storage temperature is a major factor affecting

the risk of multiplication; <5ºC will retard, but not prevent, multiplication

storage times of food should be kept to a minimum

Page 145: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control Consumer control

potentially unsafe foods should not be kept between 4ºC - 60ºC more than 4 hours between buying and eating

thoroughly cooking meat (71ºC), poultry (85ºC), seafood

thorough scrubbing of vegetables, do not cook too far in advance since this increase likelihood of bacterial growth

Page 146: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Control Consumer control

avoid cross-contamination - clean utensils, disinfect surfaces, proper hygiene, separate cutting surfaces for raw and cooked meats and vegetables

thaw food in the refrigerator, then keep refrigerated but only for short period, then discard

serve foods hot (>60ºC) or cold (<4ºC)

Page 147: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Listeria monocytogenes

Recent multistate outbreak, 1998-1999 at least 50 cases caused by a rare strain of

Listeria monocytogenes (serotype 4b) reported to CDC by 11 states onset August 2 - December 13, 1998 vehicle for transmission: hot dogs and

possibly deli meats under several brands but all by same manufacturer: Bil Mar Foods

massive product recall in OH, NY, TN, MI, MA, VT, GA, MN, WI, MO, AK, AL, CT, OR

Page 148: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 149: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food-borne disease

Fight BAC! Partnership for Food Safety Education

program aimed at educating food handlers and food preparers Clean Separate Cook Chill

Page 150: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food-borne disease

HACCP Hazard Analysis and Critical Control

Point USDA/FSIS program implemented in all plants

processing meat and poulty Pathogen reduction standards for Salmonella

and E coli Implementation began in 1997, to be completed

as of Jan 2000

Page 151: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food-borne disease

Food Compliance Programs FDA/CFSAN (Center for Food Safety Applied

Nutrition) Issued for 3 years; re-issued every three years or

more frequently as needed Guidance for inspection, investigation,

administration Apply to imported and domestic products

Acidified/low-acid canned foods Milk and cheese products Drug residue in milk Milk safety Mycotoxins Medical foods Infant formulas

Page 152: Foodborne pathogens It can be classified into three forms: foodborne intoxication
Page 153: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing Cross-Contamination

Separate raw animal foods during storing, preparing, holding, and display from raw ready-to-eat food and cooked ready-to-eat food.

Separate types of raw animal foods from each other.

Clean and sanitizing equipment and utensils. Store food in packages, covered containers,

or wrappers.

153(continued)

Page 154: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing Cross-Contamination

Clean hermetically sealed containers of food of visible soil before opening.

Protect food containers that are received packaged together in a case or overwrap from cuts when the case or overwrap is opened.

Store damaged, spoiled, or recalled food separately.

Separate fruits and vegetables before they are washed.

154

(continued)

Page 155: Foodborne pathogens It can be classified into three forms: foodborne intoxication

HandwashingBefore:

Handling foodHandling clean utensilsHandling clean equipment

After:EatingDrinkingSmokingTouching the face or hairUsing the toiletHandling raw meat, poultry, or seafoodHandling soiled utensils or equipment

155

Page 156: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Handling a Foodborne Illness Complaint

1. One person responsible for the investigation

2. Listen to complaint3. Get the facts4. Evaluate guest complaint5. Notify health officials if complaint

appears valid6. Isolate suspected food

156(continued)

Page 157: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Handling a Foodborne Illness Complaint

7. Cooperate with heath officials8. Take corrective action9. Close the complaint with the

guest10.Index complaint11.Follow up

157

(continued)

Page 158: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Common Causes of Food Spoilage

Improper storage temperatures Incorrect storage times Improper ventilation Failure to separate foods Excessive delays between receiving

and storing Inadequate food safety standards

158

Page 159: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Low-Temperature Food Preservation

Chilled storage: 50˚F (10˚C) to 59˚F (15˚C)

Refrigerated storage: 32˚F (0˚C) to 45˚F (7˚C)

Freezer storage: 0˚F (–18˚C) or below

159

Page 160: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Pasteurization

High-temperature food preservationFood product heated to 145˚F (63˚C) for 30 minutes or to 161˚F (72˚C) for 15 seconds then immediately cooled to 50˚F (10˚C) or less.

160

Page 161: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Sterilization

High-temperature food preservationVirtually kills all microorganisms and their spores.Heating usually takes place in a large container which is pressurized according to the food product, its ability to withstand heat, and packaging.

161

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Page 163: Foodborne pathogens It can be classified into three forms: foodborne intoxication

High risk foods

Some foods are high-risk, as they provide the ideal conditions needed for micro-organisms to grow.

These include:

• meat and meat products;

• milk and dairy products;

• fruit.

If these foods become contaminated with food-poisoning micro-organisms and conditions allow them to multiply, the risk of food-poisoning increases.

Page 164: Foodborne pathogens It can be classified into three forms: foodborne intoxication

People at high risk

Elderly people, babies and anyone who is ill or pregnant needs to be extra careful about the food they eat.

For example, pregnant women or anyone with low resistance to infection should avoid high risk foods such as unpasteurised soft cheese.

Page 165: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Factors affecting food poisoning

Some common factors leading to food poisoning include:

• preparation of food too far in advance;

• storage at ambient temperature;

• inadequate cooling;

• inadequate reheating;

• under cooking;

• inadequate thawing.

Page 166: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Factors affecting food poisoning

More common factors leading to food poisoning include:

• consuming raw food;

• improper warm holding (i.e. holding ‘hot’ food below 63ºC);

• infected food handlers;

• contaminated processed food;

• poor hygiene.

Page 167: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Symptoms of food poisoning

Food poisoning can be mild or severe.

The symptoms will be different depending on what type of bacteria is responsible.

Common symptoms include:• severe vomiting;• diarrhoea;• exhaustion;• headache;• fever;• abdominal pain;• tiredness.

Page 168: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food spoilage, contamination and poisoning

Tips for buying food include:

• it is illegal to sell food that has passed its ‘use by’

date;

• dented, blown or rusted cans of food should not be

purchased;

• frozen food which has frozen together in the pack

should not be purchased;

• do not buy food where the packaging has been

damaged;

• only shop in clean and hygienic stores.

Page 169: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food spoilage, contamination and poisoning

Tips for transporting food back home:

• buy chilled and frozen foods at the end of the

shopping trip;

• keep frozen and chilled foods cold, by using cool

boxes/bags and packing these types of foods together;

• cooked and uncooked foods

should be kept separate;

• dry and moist foods

should be packed separately;

• household chemicals

should be packed separately.

Page 170: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Preventing food spoilage, contamination and poisoning

Tips for storing food in the home:

• food should be unpacked as soon as possible;

• old stocks of food should be used before buying

new ones (first in, first out theory);

• store food in the correct place, i.e. dry food, in cool,

dry clean places and chilled food in the refrigerator.

Page 171: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Clostridium botulinum

High risk foods

Inadequately processed canned meat, vegetables and fish (faulty canning)

Signs and symptoms

Onset 24 – 72 hours. Voice change, double vision, drooping eyelids, severe constipation.

Death within a week or a slow recovery over months.

Page 172: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Campylobacter

High risk foods

Meat and poultry.

Signs and symptoms

Onset 2 – 11 days. Fever, headache and dizziness for a few hours, followed by abdominal pain. This usually lasts 2 – 7 days and can recur over a number of weeks.

Page 173: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Clostridium perfringens

High risk foods

Raw meat, cooked meat dishes and poultry.

Signs and symptoms

Onset 8 – 22 hours. Abdominal pain, diarrhoea and nausea. This usually lasts 12 – 48 hours.

Page 174: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - E Coli 0157

High risk foods

Raw meat and dairy products.

Signs and symptoms

Diarrhoea, which may contain blood, can lead to kidney failure or death.

Page 175: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Salmonella

High risk foods

Raw meat, poultry and eggs, and raw unwashed vegetables.

Signs and symptoms

Onset 12 – 36 hours. Headache, general aching of limbs, abdominal pain and diarrhoea, vomiting and fever. This usually lasts 1 – 7 days, and rarely is fatal.

Page 176: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Staphylococcus aureus

High risk foods

Meat, dairy products and poultry.

Signs and symptoms

Onset 1 – 6 hours. Severe vomiting, abdominal pain, weakness and lower than normal temperature. This usually lasts 6 – 24 hours.

Page 177: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Listeria Monocytogenes

High risk foodsUnpasteurised milk and dairy products, cook-chill foods, pate, meat, poultry and salad vegetables.

Signs and symptomsRanges from mild, flu-like illness to meningitis, septicaemia, pneumonia. During pregnancy may lead to miscarriage or birth of an infected baby.

Page 178: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Bacteria - Bacillus cereus

High risk foodsRice, meat, seafood, salads, potatoes, and noodles.

Signs and symptomsRanges nausea and vomiting and abdominal cramps and has an incubation period of 1 to 6 hours . This usually lasts less than 24 hours after onset.

Page 179: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Review of the learning objectives

To recognise the seriousness of food poisoning.

To identify high risk foods To identify people at risk of food poisoning. To identify factors affecting food poisoning. To identify methods of shopping safely to

prevent food poisoning. To recognise common bacteria involved in

food poisoning.

Page 180: Foodborne pathogens It can be classified into three forms: foodborne intoxication

Food-Borne Diseases

People get sick with a food-borne disease when they consume foods or beverages contaminated with disease-causing microbes, chemicals, insects or other harmful substances


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