Advanced Certificate in Nutrition - Foodborne Illness PDF

Advanced Certificate in Nutrition Foodborne illness: Bacteria Dr. Rachel Ching [email protected] 1 Learning outcome • Understand the difference between foodborne infection and intoxication • Explain the main causes of foodborne illness • Recognize the characteristics, reservoir, mode of trans...

Advanced Certificate in Nutrition Foodborne illness: Bacteria Dr. Rachel Ching [email protected] 1 Learning outcome • Understand the difference between foodborne infection and intoxication • Explain the main causes of foodborne illness • Recognize the characteristics, reservoir, mode of transmission, associated illness of the microorganisms that commonly cause foodborne illness Foodborne illness • Also known as Food poisoning • An illness caused by the ingestion of food/water containing substances that elicit clinical symptoms after ingestion • Common symptoms § Vomiting § Diarrhea § Abdominal pain § Fever § Chills 4 Foodborne illness 1. Infectious agents (pathogens) § Bacteria § Molds § Viruses § Parasites (Protozoa) 2. A toxin or chemical § Toxins produced by microorganisms § Other chemical contaminants • Pesticides, Heavy metals 5 Types of foodborne illness 1. Foodborne infection § Caused by the consumption of food containing live pathogenic microorganisms which grow and establish themselves in the human intestinal tract § Viable cells, even if present in small numbers, have the potential to multiply and grow to cause illness 2. Foodborne intoxication § Caused by ingesting food containing toxins formed by microorganisms which resulted from the microbial growth in the foods § It occurs even in the absence of viable cells in consumed foods § In this case, it is not the microbe that makes people sick but the toxin it produces § Killing the microbes may not be enough to prevent the cases of food intoxication if the toxin is still present and has not damaged, the person will still become ill 6 Foodborne illness – A common public health problem • In 2015, WHO estimated 600 million (~ 1 in 10) people in the world have suffered from a foodborne disease every year § Resulting in 420 000 death, including 125 000 children under the age of 5 years § Most of these illnesses are due to microorganisms § Salmonella and Campylobacter account for over 90% of all reported cases of bacteria related to food poisoning worldwide § As most cases of foodborne diseases are not reported, the true situation is unknown 7 Foodborne illness – A common public health problem • In HK, 229 cases of foodborne disease reported in 2020, affecting 632 persons § Contaminated by raw food, contamination by food handlers and improper holding temperature were the three most frequently identified contributing factors § Bacterial foodborne agents remained the leading causes (90%) § Top TWO bacterial pathogens 1. 2. Salmonella 沙⾨⽒菌 Vibrio parahaemolyticus 副溶⾎性弧菌 Figure 1: Number of food poisoning outbreaks related to food premises and 8 food business and the corresponding number of persons affected from 2010 to 2020. Common foodborne illness 1. Gastroenteritis 腸胃炎 • Also known as “Stomach flu” • Most common • Pathogens colonize intestines § Inflammation of epithelial cells of intestines § Production of enterotoxin • Interfere with nutrient/water absorbing function • Symptoms § Watery diarrhea § Vomiting § Abdominal pain 9 Common foodborne illness 2. Dysentery 痢疾 • Pathogens colonize large intestine § Cellular damaged to the lining of large intestine § Production of cytotoxin • Cell-damaging toxin • Symptoms § Bloody diarrhea - severe diarrhea with the presence of blood and mucus in the feces 10 Common foodborne illness 3. Emetic disease 催吐病 • Vomiting • Stimulation to the stomach 4. Septicemia 敗⾎症 • Blood infection (blood poisoning) • It sometimes has no symptoms • When there are symptoms, they can include: § Sudden high fever with chills § Rapid heart rate § Gastrointestinal symptoms 11 Common foodborne illness 5. Liver infection • Liver colonization • Infective microbes absorbed by intestines à blood à liver 6. Neural disease • Infective microbes or toxins • Act on central nervous system 7. Kidney disease • Microbial toxin transported to kidney à kidney damage 12 Sources of pathogenic microorganism • Raw food § E.g. raw meats, poultry, fish and shellfish • Soil § E.g. unwashed vegetables and salads • Human § Poor worker hygiene § E.g. Hands, hair, clothing and infected cuts • Untreated water • Poor sanitation practices during production process • Improper treated animal wastes (animal feces) 14 Main causes of foodborne illness • Poor sanitation § Contamination by food handlers / contaminated cooking utensils § Cross contamination of ready-to-eat food by raw food • Prolonged storage and inappropriate storage temperatures (E.g. 5 – 60°C) • Raw and undercooked foods 15 16 Pathogens in food Bacteria Viruses A pathogen is a microorganism capable of causing a disease Molds Parasites (Protozoa) 17 Pathogenic bacteria in food • Pathogenic bacteria Bacteria § Disease-causing § The living microorganism or a toxin (microbial product) must be consumed to cause symptoms 18 Examples of pathogenic bacteria Foodborne Infection Foodborne Intoxication • Vibrio parahaemolyticus • Vibrio cholerae • Salmonella • Escherichia coli • Shigella • Listeria monocytogenes • Staphylococcus aureus • Bacillus cereus • Clostridium botulinum Bacteria 19 Pathogenic viruses in food • They are smaller than bacteria • Viruses do NOT grow on foods • When consumed in foods, they can grow in the human body à Foodborne illness • Examples § Norovirus § Hepatitis A 20 Pathogenic molds in food • Molds are fungi that live on plant or animal matter • Growth Molds § Mainly on breads, cheese, fruits • Production of mycotoxins § Poisonous substances that can make people sick § Cause foodborne intoxication § E.g. Ergot poisoning, Aflatoxin poisoning 21 Pathogenic parasites in food • A parasite is an organism that lives on or in a host organism and gets its food from its host • Some are small one-celled microorganisms called Protozoa • Protozoa § One-celled aquatic organisms § Free-living or parasitic in nature § Able to grow in human § Some can produce toxins § Examples of protozoa Parasites((Protozoa) Dinoflagellate • Cryptosporidium spp. (also known as "Crypto") • Dinoflagellates Red tides are caused by toxic dinoflagellate blooms 22 Bacteria Bacterial pathogens causing foodborne infection 23 1. Vibrio parahaemolyticus 副溶⾎性弧菌 Characteristics • • • • • Curved, rod-shaped Gram-negative Facultative anaerobic Motile Not spore-former Growth • • • Mesophilic Halophilic (= salt lover) Destroyed by heating 60°C for 15 minutes Types of illness Bacterial infection Reservoir • • Mode of transmission Raw or undercooked seafood Onset time 12-24 hours Symptoms Gastroenteritis • Watery diarrhea • Fever • Headache • Nausea Occasionally dysentery • Diarrhea with occasional blood or mucus in stool Marine coastal fish and shellfish Highest concentration in summer to early autumn 24 2. Vibrio cholerae 霍亂弧菌 Characteristics • • • • • Curved, rod-shaped Gram-negative Facultative anaerobic Motile Not spore-former Growth • • • Mesophilic Halophilic (= salt lover) Organism is resistant to freezing but sensitive to heat and acid Types of illness Toxico-infection - Infect intestinal epithelial cells and produce cholera toxin (enterotoxin) Reservoir • • Intestinal tract of man (present in feces) Untreated sewage and marine environment Mode of transmission • • • Water, ice, fruit or vegetable refreshed with sewage polluted water Raw or undercooked seafood Food and water contaminated through contact with fecal matter or infected food handlers Onset time 1-4 days Symptoms Gastroenteritis (Cholera) • Watery diarrhea with rice water like stool • Vomiting • Dehydration • Muscular cramp • Abdominal pain 25 3. Salmonella spp. 沙⾨⽒菌 Characteristics • • • • • Rod Gram-negative Facultative anaerobic Motile Not spore-former Growth • Mesophilic Types of illness Bacterial infection • Over 2000 types causing illnesses to man • Accounts for over 25% of food poisoning cases • 2 forms of Salmonella infection a. Enteric (typhoid) fever b. Gastroenteritis 26 3a. Salmonella typhi - Typhoidal 傷寒沙⾨⽒菌 Characteristics • • • It causes Enteric (typhoid) fever Must have high dosage in food: 104-106 CFU/ml May cause liver damage (Gastrointestinal tract à blood à the liver) • Human • Contaminated food and water • Water • Shellfish • Fruit • Vegetable • Milk and diary products Flies Growth Types of illness Reservoir Mode of transmission • Onset time 1-2 weeks (It takes long time for the bacteria to reach and colonize the liver) Symptoms • • • • • High fever Abdominal pain Headaches Intestinal bleeding Mortality (10-30% without treatment) 27 28 3b. Salmonella enteritidis – Non typhoidal 腸炎沙⾨⽒菌 Characteristics • • • Gastroenteritis-causing Salmonella spp. Low infective dosage: < 103 CFU/g Invade intestinal mucosa à Gastroenteritis (intestinal salmonellosis) • Poultry, domestic and wild animals • • • Poultry Milk Eggs Growth Types of illness Reservoir Mode of transmission Onset time 6-24 hours Symptoms • • • Diarrhea Abdominal cramps Fever 29 4. Escherichia coli ⼤腸桿菌 Characteristics • • • • • Rod-shaped Gram-negative Facultative anaerobic Non-motile Not spore-former Growth • Mesophilic • • Most strains are harmless, but some cause foodborne illness E. coli pathogens a. Enterotoxigenic (ETEC) – traveler diarrhea b. Enterohemorrhagic O157: H7 (EHEC) – bloody diarrhea Types of illness 30 4a. Enterotoxigenic E. coli (ETEC) 產腸毒素⼤腸桿菌 • • Produce enterotoxin Illness: gastroenteritis Types of illness • Toxico-infection Reservoir • Human • • • • • Consumption of food and water contaminated with fecal matter Time temperature abuse Foods involved include ground (minced) meat, raw milk, and vegetables Up to 25% of infections in infants and young children in developing countries are due to E. coli ETEC is a major cause of traveler's diarrhea in developing countries. • Travelling in underdeveloped counties where sanitation is poor Characteristics Growth Mode of transmission Onset time 16-48 hours Symptoms • • Cause excessive loss of fluid diarrhea Also cause fever and abdominal pain 31 4b. Enterohemorrhagic O157: H7 (EHEC) 腸出⾎性⼤腸桿菌 Characteristics • Produce cytotoxin Types of illness • Toxico-infection Reservoir • Cattle Mode of transmission • Raw or undercooked beef Onset time • 3-4 days Symptoms • • • Dysentery Gastroenteritis Kidney damage Growth 32 4b. Enterohemorrhagic O157: H7 (EHEC) 腸出⾎性⼤腸桿菌 • Famous E. coli O157: H7 outbreak § In 1993, 732 people were affected by one of the most notorious and tragic cases of food poisoning in US history • Jack in the Box, a fast-food hamburger chain, sold hamburgers with under-cooked beef patties that infected many customers with E. coli bacteria • The outbreak involved 73 restaurants across the US § The under-cooked burger patties were responsible for the deaths of 4 children and the serious injury of 178 other victims, including permanent kidney and brain damage 33 5. Shigella spp. 志賀⽒菌 Characteristics • • • • • Rod-shaped Gram-negative Facultative anaerobic Non-motile Not spore-former Growth • Mesophilic Types of illness Bacterial infection • Common species • Shigella dysenteriae (severe symptoms) • Shigella sonnei (most common) • Severely invade intestinal mucosa • Produce cytotoxin (“Shiga” toxin) Reservoir • Intestinal tract of human Mode of transmission • • Food or water contaminated by human feces Flies Onset time • Several days Symptoms • • • • Abdominal cramp Fever Watery diarrhea (Shigella sonnei) Bloody diarrhea (Shigella dysenteriae) 34 6. Listeria monocytogenes 李斯特菌 Characteristics • • • • • Short rod Gram-positive Facultative anaerobic Non-motile Not spore-former Growth • • Psychrophilic (survive through freezing) Salt tolerant (10% salt) Types of illness Bacterial infection • Illness: Listeriosis (gastroenteritis) • Intestinal infection • Mild in healthy adults • Serious infection in high-risk groups • Elderly • Infant • Pregnant woman • People with weakened Immune system 35 6. Listeria monocytogenes 李斯特菌 • • • Domestic and wild animals Soil and vegetation Human • • Dairy products (soft-serve ice cream, cheese), cold cured meats, smoked salmon Infection is transmitted from mother to fetus Onset time • Days to several weeks Symptoms • • • • • Flu-like symptoms such as fever, headache and occasionally gastrointestinal symptoms Abortion in pregnant woman Septicaemia (affects blood stream) Inflammation of the membranes around the brain High mortality rate up to 30% Reservoir Mode of transmission 36 Bacteria Bacterial pathogens causing foodborne intoxication 37 1. Staphylococcus aureus ⾦⿈⾊葡萄球菌 • • • • • Cocci Gram-positive Facultative anaerobic Non-motile Not spore-former Growth • • Mesophilic Halophilic Types of illness Bacterial intoxication • Produce heat-stable enterotoxin in food • Require heating up to 118°C for 20 min to destroy the enterotoxin • It is therefore possible for well-cooked food to cause illness without containing viable organisms Reservoir • • Characteristics Human – major reservoir Present in the skin, nose, throat, nasal and oral secretions , fingernails, wounds of food handlers 38 1. Staphylococcus aureus ⾦⿈⾊葡萄球菌 • • Food which has been handle then consumed without further treatment Food stored at ambient temperature for several hours supporting rapid growth and production of enterotoxin • 2-6 hours • Illness: Staphylococcal food poisoning/intoxication (Gastroenteritis) • Nausea • Vomiting • Diarrhea • Abdominal cramp • Prostration • Subnormal body temperature in minor cases Mode of transmission Onset time Symptoms 39 2. Clostridium botulinum ⾁毒桿菌 Characteristics • • • • • Rod Gram-positive Anaerobic Motile Spore-former (heat resistant spores) • Growth • • Requires heating of over 100°C for 20 min to destroy the spores Mesophilic Cannot survive at pH < 4.6 Bacterial intoxication • Ingestion of toxin pre-formed in food • Produce neurotoxin • Bind to nerve ending, hamper acetylcholine release • Muscle won’t contract Types of illness Reservoir • Commonly found in soil and agricultural products 40 2. Clostridium botulinum ⾁毒桿菌 Mainly found in the cannery industry with the production of low acid food products • E.g. vegetables, fish and fish products, meat and meat products • Owing to the anaerobic condition within the canned foods, cans with inadequate retorting* will allow the spores to germinate and neurotoxins will be produced throughout the storage period of the can *Retort is the main processing chamber where in the packed food is sterilized as well as cooked properly to achieve safety and quality. The thermal processing is done inside the retort chamber • Mode of transmission Onset time Symptoms • 48 hours • Illness: Botulism • Blurring vision • Dizziness • Difficulty speaking • Followed by gradual paralysis and respiratory paralysis • Lethal dosage of the toxin is less than 0.1 ng 41 3. Bacillus cereus 蠟狀芽孢桿菌 Characteristics • • • • • Rod Gram-positive Aerobic Non-motile Spore-former (heat resistant spores) Growth • Mesophilic Types of illness Reservoir Bacterial intoxication • Ingestion of toxin pre-formed in food • Two types of toxins • Enterotoxin or Diarrheal toxin (heat liable) • Emetic toxin (heat stable) • • • Soil Water Vegetation 42 3. Bacillus cereus 蠟狀芽孢桿菌 • • • Mode of transmission • • Onset time • • Symptoms • Storage of cooked foods at ambient temperature • More than 12 hours • Foods involved include starchy products such as boiled or fried rice, spices, dried foods, milk, dairy products, vegetable dishes, and sauces Under improper storage conditions of contaminated foodstuff, spores germinate, and the vegetative cells grow and produce toxin For gastroenteritis • Foods (e.g. meat dish, cream pastry, pudding) with 105 - 108 CFU/g are susceptible For emetic disease • Foods (e.g. boiled or fried rice) with 103 - 1010 CFU/g are susceptible For gastroenteritis • 8-16 hours For emetic disease • 2-6 hours Enterotoxin à Gastroenteritis / Diarrhoeal syndrome • Acute diarrhoea, abdominal pain Emetic toxin à Emetic syndrome • Vomiting 43 Case study question 1 • A 22-year-old male college student had severe vomiting a couple of hours after digesting old fried rice. Which of the following organisms is most likely to be responsible for this patient's symptoms? A. B. C. D. E coli O157:H7 Salmonella Clostridium botulinum Bacillus cereus 45 Case study question 2 • A 30-year-old lady felt muscle paralysis and difficult to breath. She reported she ate canned fish with rice a day before. Which of the following organisms is most likely to be responsible for this patient's symptoms? A. B. C. D. E coli O157:H7 Salmonella Clostridium botulinum Bacillus cereus 46 Case study question 3 • Food poisoning outbreak at ABC Hospital. An outbreak of food poisoning occurred among the 10 children. They had severe bloody diarrhea >3 days after eating dinner in BBQ farm. Which of the following organisms is most likely to be responsible for this patient's symptoms? A. B. C. D. E coli O157:H7 Salmonella Clostridium botulinum Bacillus cereus 47 Self-check exercise 1. What is the difference between foodborne intoxication and infection? 2. Which two foodborne pathogens have caused over 90% of worldwide bacteria-related foodborne illness? 3. In a case of Staphylococcal intoxication, how long does it take after exposure before symptoms are evident? 4. What types of food do Clostridium botulinum grow in? 48