4_FOODBORNE DISEASE AND EPIDEMIOLOGY

FOODBORNE PATHOGENS

May grow if food is not decontaminated or preserved, causing foodborne diseases with significant morbidity and mortality.

outbreaks

Most ___are due to improper food handling and preparation by consumers and affect small numbers of individuals.

improper food handling and preparation by consumers

Most outbreaks are due to______ and affect small numbers of individuals.

Occasional outbreaks

____affect large numbers of individuals caused by breakdowns in safe food handling and preparation at food processing

morbidity and mortality

Foodborne Pathogens may grow if food is not decontaminated or preserved, causing foodborne diseases with significant ___

Food Poisoning or Food Intoxification

A disease that results from ingestion of foods containing preformed microbial toxins

Food infection

• is the ingestion of food containing sufficient numbers of viable pathogens to cause infection and diseases in the host

• Results from ingestion of food containing sufficient numbers of viable pathogens to cause infection and diseases in the host.

Staphylococcal Food Poisoning

Caused by staphylococcal enterotoxin (SE) produced by S. aureus

staphylococcal enterotoxin (SE)

Staphylococcal Food Poisoning is Caused by ____produced by S. aureus

Staphylococcus aureus

• Small, G-positive cocci

• Normal members of the skin flora and upper respiratory tracts

• Opportunistic pathogens

• produces gastroenteritis characterized by nausea, vomiting, and diarrhea within 1-6 hours.

• Responsible foods: cream-filled baked goods, poultry, eggs, raw and processed meat, puddings, and salad dressing.

one or two toxins

Most strains of S. aureus produce ___ while some are nonproducers.

nonproducers

Most strains of S. aureus produce one or two toxins while some are ___

Staphylococcus enterotoxin

• Classified as superantigens (stimulate large numbers of T cells, which in turn release intercellular mediators called cytokines)

• In the intestine, superantigens activate a general inflammatory response that causes gastroenteritis and significant fluid loss ue to diarrhea and vomiting.

cytokines

Staphylococcal Enterotoxins is classified as superantigens stimulate large numbers of T cells, which in turn release intercellular mediators called ___

superantigens

• Staphylococcal Enterotoxins is classified as __ (stimulate large numbers of T cells, which in turn release intercellular mediators called cytokines)

• In the intestine, ___activate a general inflammatory response that causes gastroenteritis and significant fluid loss due to diarrhea and vomiting

general inflammatory response

In the intestine, superantigens activate a ____that causes gastroenteritis and significant fluid loss due to diarrhea and vomiting

gastroenteritis and significant fluid loss

In the intestine, superantigens activate a general inflammatory response that causes ____ due to diarrhea and vomiting.

high salt content and low water activity

Staphylococci thrive in habitats with a

Bacterial plate count

Diagnosis, Treatment and Prevention of Staphyloccocal infection:

• to obtain quantitative data and determine the extent of contamination

Detection of exonuclease

Diagnosis, Treatment and Prevention of Staphyloccocal infection:

• to obtain qualitative data

not effective

Diagnosis, Treatment and Prevention of Staphyloccocal infection:

• Antibiotics is ___ since food poisoning is caused by the toxins not the active bacteria.

Clostridium perfringes

• Anaerobic, G-positive, endospore-forming rods

• Endospores in food can germinate and produce toxins under favorable anaerobic conditions.

• A large dose must be ingested (>108 cells) in contaminated cooked or uncooked foods (e.g., meat, poultry, and fish)

• The ___enterotoxin alters the permeability of the intestinal epithelium leading to nausea, diarrhea, and intestinal cramps, with no fever.

• Onset begins 7-15 hours after consumption but resolves within 24 hours. Fatality is rare.

>10^8 cells

in Clostridium perfringes,  A large dose must be ingested (___) in contaminated cooked or uncooked foods (e.g., meat, poultry, and fish)

permeability of the intestinal epithelium

in Clostridium perfringes, The perfringens enterotoxin alters the ____leading to nausea, diarrhea, and intestinal cramps, with no fever.

7-15 hours

in Clostridium perfringes, Onset begins ___after consumption but resolves within 24 hours. Fatality is rare.

within 24 hours

in Clostridium perfringes, Onset begins 7-15 hours after consumption but resolves ____. Fatality is rare.

Clostridium botulinum

• Anaerobic, G-positive, endospore-forming rods

• If viable endospores remain in food, they may germinate and produce botulinum toxin.

• Ingesting even a small amount of this neurotoxin is dangerous.

• The toxin causes flaccid paralysis, affecting the autonomic nerves that control body functions (i.e., respiration and heartbeat)

• The neurotoxin is destroyed by heat; cooking can eliminate them

• Botulism is caused by eating processed food without cooking after processing.

• Spores can infect infants and germinate in its intestine

Botulism

is caused by eating processed food without cooking after processing.

flaccid paralysis

In Clostridium botulinum, The toxin causes ____, affecting the autonomic nerves that control body functions (i.e., respiration and heartbeat)

• Salmonellosis

• Pathogenic Escherichia coli

• Campylobacter

• Listeriosis

• Others (Bacteria, viruses, protists, acellular agents)

Examples of Food Infection:

Salmonellosis

Gastrointestinal disease typically caused by foodborne Salmonella infections.

• It colonizes the intestinal epithelium

• Gram-negative, facultatively aerobic, motile rods

• Salmonella enterica has 7 evolutionary subspecies (may be divided into serovars or serotypes)

• E.g., Salmonella enterica subspecies enterica serovar Typhi

• Cause thyphoid fever and some cause gastroenteritis

• Onset of disease occurs 8-48h after ingestion

• Symptoms: headache, chills, vomiting, and diarrhea, followed by a fever

• Mortality can reach 15% in untreated typhoid fever

intestinal epithelium

Salmonellosis colonizes the ____

thyphoid fever

Salmonellosis Cause ____ and some cause gastroenteritis

8-48h after ingestion

Onset of Salmonellosis occurs ____

intestinal tracts

Ultimate sources of the foodborne salmonellas are the ___of humans and other warm-blooded animals

• fecal contamination from food handlers

• food production animals harbored with Salmonella serovars

• finished fresh foods (eggs, meat and dairy products)

Bacteria can reach food supply through

• Start with uptake of the organisms

• Invades phagocytes and grows as an intracellular pathogen

• Spread to adjacent cells as host cells die

• Pathogenic Salmonella uses a combination of endotoxins, enterotoxins, and cytotoxins to damage and kill host cells

• Leading to salmonellosis

Pathogenesis of Salmonellosis:

Escherichia coli

Most ____ is part of the enteric microflora in human colon and not pathogenic but a few strains are potential foodborne pathogens.

Shiga toxin-producing Escherichia coli (STEC)

Pathogenic strains are divided based on the type of toxins the produce and specific disease they cause:

• produce verotoxin (an enterotoxin) that cause hemorrhagic diarrhea and kidney failure.

• E. coli O157:H7 caused 90% of all _____ infections

Enterotoxigenic E. coli (ETEC)

Pathogenic strains are divided based on the type of toxins the produce and specific disease they cause:

• produce heat-labile, diarrhea-producing enterotoxins

• cause “traveler’s diarrhea”

Enteropathogenic E. coli (EPEC)

Pathogenic strains are divided based on the type of toxins the produce and specific disease they cause:

• Not cause invasie disease or produce toxins

• cause diarrheal disease in infants and children

Enteroinvasive E. coli (EIEC)

Pathogenic strains are divided based on the type of toxins the produce and specific disease they cause:

• cause invasive disease in the colon, producing watery and sometimes bloody diarrhea

E. coli O157:H7

caused 90% of all STEC infections

verotoxin

Shiga toxin-producing Escherichia coli (STEC) produce ___  (an enterotoxin) that cause hemorrhagic diarrhea and kidney failure.

“traveler’s diarrhea”

Enterotoxigenic E. coli (ETEC) cause ____

Campylobacter

Most common reported cause of bacteria foodborne infections

• Gram-negative, motile, curved rods to spiral-shaped

• Grow in microaerophilic conditions

• Campylobacter jejuni and C. coli cause bacterial diarrhea

• C. fetus cause of sterility and spontaneous abortion in cattle and sheep

C. fetus

cause of sterility and spontaneous abortion in cattle and sheep

C. jejuni

• is a normal resident in the intestinal tract of poultry

• is sensitive to gastric acid, thus as high as 104 cells are required to initiate infection

Erythromycin and quinolone

Treatment for Campylobacter requires ____ for sever diarrhea

Listeria monocytogenes

is an intracellular pathogen that causes listeriosis, a gastrointestinal food infection that may lead to bacteremia and meningitis,

• Short, Gram - positive, nonsporulating coccobacillus

• Acid-, salt- and cold-tolerant

• Facultatively aerobic

bacteremia and meningitis

Listeria monocytogenes Causes listeriosis, a gastrointestinal food infection that may lead to ____

listeriolysin O

Pathogenesis of Listeria monocytogenes:

• Phagocytes take up the pathogen in a phagolysosome

• Cells release ___that lyses the phagolysosome and release L. monocytogenes in the cytoplasm

• Cells multiply and produce ActA (a protein that induces host Cell actin polymerization)

• Cytoplasmic complex forms filopods (a protrusion), which will be ingested by surrounding cells to start the cycle again.

• This allows cells to move from cell to cell without exposure to antibodies, complement, or neutrophils.

ActA

Pathogenesis of Listeria monocytogenes:

• Phagocytes take up the pathogen in a phagolysosome

• Cells release listeriolysin O that lyses the phagolysosome and release L. monocytogenes in the cytoplasm

• Cells multiply and produce ____(a protein that induces host Cell actin polymerization)

• Cytoplasmic complex forms filopods (a protrusion), which will be ingested by surrounding cells to start the cycle again.

• This allows cells to move from cell to cell without exposure to antibodies, complement, or neutrophils.

filopods

Pathogenesis of Listeria monocytogenes:

• Phagocytes take up the pathogen in a phagolysosome

• Cells release listeriolysin O that lyses the phagolysosome and release L. monocytogenes in the cytoplasm

• Cells multiply and produce ActA (a protein that induces host Cell actin polymerization)

• Cytoplasmic complex forms ___(a protrusion), which will be ingested by surrounding cells to start the cycle again.

• This allows cells to move from cell to cell without exposure to antibodies, complement, or neutrophils.

• without exposure to antibodies, complement, or neutrophils.

Pathogenesis of Listeria monocytogenes:

• Phagocytes take up the pathogen in a phagolysosome

• Cells release listeriolysin O that lyses the phagolysosome and release L. monocytogenes in the cytoplasm

• Cells multiply and produce ActA (a protein that induces host Cell actin polymerization)

• Cytoplasmic complex forms filopods (a protrusion), which will be ingested by surrounding cells to start the cycle again.

• This allows cells to move from cell to cell ____

phagolysosome

Pathogenesis of Listeria monocytogenes:

• Phagocytes take up the pathogen in a ___

• Cells release listeriolysin O that lyses the phagolysosome and release L. monocytogenes in the cytoplasm

• Cells multiply and produce ActA (a protein that induces host Cell actin polymerization)

• Cytoplasmic complex forms filopods (a protrusion), which will be ingested by surrounding cells to start the cycle again.

• This allows cells to move from cell to cell without exposure to antibodies, complement, or neutrophils.

penicillin, ampicillin, or trimethoprim plus sulfamethoxazole

Treatment of Listeria monocytogenes involves Intravenous treatment with

Yersinia enterocolitica

Found in the intestines of domestic animals and causes foodborne infections due to contaminated meat and dairy products.

• Gram-negative, rod-shaped bacterium that causes the infection yersiniosis

• Cause gastrointestinal issues and systemic infections

• Cause enteric fever and sepsis (a severe life-threatening infection)

yersiniosis

Yersinia enterocolitica causes the infection ___

enteric fever and sepsis

Yersinia enterocolitica causes ___ (a severe life-threatening infection)

Bacillus cereus

Produces toxins that cause food poisoning and non-gastrointestinal infections.

Emetic (vomiting) syndrome and Diarrheal syndrome

Distinct types of food poisoning:

Emetic (vomiting) syndrome

Distinct types of food poisoning:

• Ingestion of a pre-formed toxin called cereulide, which is heat-stable and cannot be destroyed by reheating.

Diarrheal syndrome

Distinct types of food poisoning:

• Ingestion of a large number of B. cereus spores, which then produce enterotoxins in the small intestine.

• Endophthalmitis

• Bacteremia and sepsis

• Meningitis

• Pneumonia

Invasive infections:

cereulide

Emetic (vomiting) syndrome is the ingestion of a pre-formed toxin called ___, which is heat-stable and cannot be destroyed by reheating.

Shigella species

Causes severe invasive gastrointeritis called shigellosis, a result of fecal-oral contamination.

• Gram-negative rod-shaped bacterium

• Produce Shiga toxins

• Shigellosis is extremely contagious, as it takes only a small number of germs to make someone sick. It is transmitted through the fecal-oral route.

• Symptoms: Diarrhea, fever, stomach pain, cramping, and tenderness, nausea and vomiting, tenesmus

• Treatment may vary depending on the seversity of the infection

shigellosis

• Shigella sp. causes severe invasive gastrointeritis called ___, a result of fecal-oral contamination.

• is extremely contagious, as it takes only a small number of germs to make someone sick. It is transmitted through the fecal-oral route.

Vibrio species

Cause food poisoning who consume contaminated seafoods.

• A comma-shaped, gram-negative bacterium, and motile

• Species: Vibrio cholerae, V. parahaemolyticus, V. vulnificus, and V. alginolyticus

• Route of infection: wound exposure and consumption of raw food

• Infection can lead to:

  • Gastrointestinal infection

  • Wound infection

  • Bloodstream infection (septicemia)

Viruses

Viral food borne illness consists of gastroenteritis characterized by diarrhea, often accompanied by nausea and vomiting.

• Acquired through oral-fecal route

• Examples:

  • Noroviruses cause acute gastroenteritis and “stomach flu”

  • Rotavirus and astrovirus cause gastroenteritis

  • Hepatitis A causes liver disease

• They inhabit the gut and are often transmitted to food or water with fecal matter.

• Proper food handling, hand-washing, and a source of clean water to prepare fresh foods are essential to prevent infection

Noroviruses

viruses that cause acute gastroenteritis and “stomach flu”

Rotavirus and astrovirus

viruses that cause gastroenteritis

Hepatitis A

viruses that causes liver disease

Protists

Can contaminate food and water, leading to gastrointestinal illness

• Example pathogens

  • Giardia duodenalis cause Giardiasis

  • Cryptosporidium parvum causes Cryptosporidiosis

  • Cyclospora cayetanensis causes Cyclosporiasis

  • Toxoplasma gondii causes Toxoplasmosis

    • prenatal infection of the fetus can lead to complication such as myocarditis, blindness, and stillbirth.

• Sources:

  • Foods contaminated with fecal matter in untreated water used to wash, irrigate or spray crops.

  • Fresh fruits as the common source

Giardiasis

Giardia duodenalis cause

Giardia duodenalis

cause Giardiasis

Cryptosporidiosis

Cryptosporidium parvum causes

Cryptosporidium parvum

causes Cryptosporidiosis

Cyclosporiasis

Cyclospora cayetanensis causes

Cyclospora cayetanensis

causes Cyclosporiasis

Toxoplasmosis

Toxoplasma gondii causes

Toxoplasma gondii

causes Toxoplasmosis

myocarditis, blindness, and stillbirth

prenatal infection of the fetus can lead to complication such as

Prions

are proteins that adopt novel conformations, inhibiting normal protein function and causing degeneration of neural tissue.

bovine spongiform encephalopathy (BSE)

• Prions are linked to consumtion of meat products from cattle afflicted with ____

• is a prion disease called “madcow disease”

• The brain of the infected patient appears “spongy” and characterized by large vacuoles in brain tissue.