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Gastroenteritis & Food Poisoning Dr . Thamina Sayyed Registrar – Microbiology KKUH 1 Gastroenteritis Syndromes of diaeehea & vomiting that tend to involve non infalmmatory infection in the small bowel or inflammatory infection of large bowel.e.g E.coli.Yersinia campylobacter,clostridium,cryptosporidium,cyclospora.rotavirus etc Foodborne Diseases Apply to illnesses acquired by consumption of contaminated food. Sometimes incorrectly referred to as food poisoning. Includes : foodbornee intoxications foodbornee infections. 2 There are two types of food poisoning : food infection and food intoxication. 1)Food infection you eat microbes and they grow in the gut and produce an infection e.g Campylobacter jejuni, Salmonella spp., Salmonella typhii, Shigella spp., Vibrio cholerae, Vibrio parahemolyticus, Vibrio vulnificus 2) Food intoxication you eat food containing a toxin and that poison makes you sick (Staphylococcus aureus ) including bacterially produced exotoxins, 3 People at risk Food poisoning is more likely to affect people with lowered resistance to disease than healthy people who might show mild symptoms or none at all. The following are particularly vulnerable to food poisoning: - Elderly or sick people - Babies - Young children Pregnant women 4 Factors affecting microbial growth in food • Time Moisture Food Warmth Intrinsic: conditions present in food – Water availability (aw): amount of water in food (pure water is 1.0) • Most food >0.98; most bacteria require >0.90 – pH: most pathogens not grow at pH<4.5 (except Lactic acid bacteria) – Nutrients • Extrinsic: – Storage temperature <0. 0C no growth (water crystallizes) Refrigerator: 4⁰C to 10⁰C (enzyme rxns very slow or non- existent – Atmosphere: availability of O2 5 In ideal conditions where there is Moisture, Food and Warmth (37degrees centigrade is ideal), bacteria can double every 10 to 20 minutes. They do this by dividing in to two. This is called Binary Fission 6 Spore Spore forming inside cell A resting resistant phase of some bacteria (including Clostridium Perfringens and Botulinum and Bacillus Cereus). The bacterium produces a protective coat which helps it to survive high temperatures (up to 120°C) and lack of water. When favourable conditions return, the spores split open and release the bacteria which are then able to grow and multiply 7 What Foods Are Most Likely to be Contaminated? raw meat and poultry raw eggs (even in uncooked brownie, cake, or cookie dough) unpasteurized milk raw shellfish unwashed raw fruits and vegetables unpasteurized fruit juice 8 Sources of microbial contamination of food Food handler : bad personal hygiene, using same cutting board for meat & vegetables, knife contaminated by blood Food processing: equipment ,packaging ,personal contamination during processing Food storage: time & temp Fecal contamination in farms prior to collection 9 Types of bacteria Spoilage: Not particularly harmful bacteria which cause food to go off Beneficial: “Good Bacteria” which are used to make yoghurt and cheese Pathogenic: Illness causing bacteria 10 Symptoms of Microbiological Food Poisoning Infections require an incubation period of generally 2 to 3 days. Typical symptoms: abdominal cramps diarrhea nausea, but…..there can be harsher long-lasting effects. Intoxications are often immediate, (sometimes with 20 minutes) with nausea, abdominal cramps and violent vomiting. Illness is usually rather short-lived. 11 Symptoms of food poisoning Nausea Abdominal pain Vomiting Diarrhea Gastroenteritis Fever Headache Fatigue 12 Causes of foodborne disease 13 What Are the Most Common Causes of foodborne Illness? Those caused by the bacteria: • Campylobacter • Salmonella • E. coli O157:H7 Those caused by a group of viruses: • Norwalk and Norwalk-like viruses 14 Causes of foodborne disease Infectious Bacterial Virus Non-infectious protozoae Biological Nonbiological 15 Infectious causes of food poisoning Bacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing bacilli Shigella species. E.coli Yersinia enterocolitica Vibrio parahaemolyticus, Aeromonas hydrophilia, Streptococcus species Group C, E and G . The other e.g. Listeria monocytogens Viruses: a- Hepatitis A b- Hepatitis E c- Smal lrounded structured viruses (SRSV) e.g. Norovirus Caliciviruse s Astroviruse s Rotaviruses Protozoae 1- Giardiasis. 2- Amoebiasis 3 Cryptosporiosis 4- Isospora 5- Balantidum 6- Blastocytosis hominis 7- Microsporidia 8- Toxoplasmosis (?) 16 Causes Of foodborne Viruses Unlike bacteria viruses do not multiply in Foods. Acquired by: a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables e.g Hepatitis A From Vegetables irrigated by untreated water. b- Secondary contamination. From Food handlers e.g. Hepatitis A 17 Non infective causes of food poisoning Non biological Physical contamination:objects falling in to food – metal, glass, packaging materials etc. Biological Chemical contamination:Bleach, cleaning chemicals getting in to food ,heavy metals Natural contamination: Poisonous plants and berries, undercooked red kidney beans 18 Causes of foodborne Diseases (Continued Biological From: a- Mushrooms b- Harmful algal species c- Fish e.g. Ciguatera Fish poisoning Scombroid Fish poisoning associated with raised Histamine levels. Paralytic shell Fish poisoning 19 20 Some Diseases Which Are Transmitted By Food But Not Considered As Food Poisoning: • • • • • 12345- Bovine tuberculosis (milk) Brucellosis (milk) Toxoplasmosis (meat) Listerosis (milk products) Mad cow diseases virus etc. 21 Exotoxins • Produced inside bacteria and secreted – Enterotoxin, Neurotoxin, Cardiotoxin • Superantigen: Type Iintense immune responsecytokinesfever, nausea, vomitting, shock (Staph aureus) • Membrane disrupting toxin: Type II lysis of cells by disrupting membrane • A-B toxins: Type III has two parts – A is active enzyme toxin that inhibits protein synthesis and kills cell – B binds to surface so toxin is transported across plasma membrane (Clostridium 22 Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens* Pathogen Typical Incubation Period Duration Typical Clinical Presentation Assorted Foods Salmonella species 1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry, produce Campylobacter jejuni 2-5 Days 2-10 Days Undercooked poultry, unpasteurized Bacterial Gastroenteritis dairy products E. coli, 1-3 Days Enterotoxigenic 3-7 Days Gastroenteritis Many foods Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce, egg 23 salad Listeria monocytogenes Variable Gastroenteritis, meningitis abortion Deli meat, hotdogs, unpasteurized dairy products Bacillus cereus 1-6 hour <24 hour Vomiting, Gastroenteritis Fried rice, meats Clostridium botulinum 12-72 hour Days-months Blurred vision, Home-canned paralysis foods, fermented fish Staphylococcu s aureus 1-6 hour 1-2 Days Gastroenteritis, particularly nausea Meats, potato & pork, unpasteurized dairy products. Yersinia enterocolitica 1-2 Days 1-3 weeks Gastroenteritis, appendicitislike syndrome Undercooked pork, unpasteurized dairy products. 24 2-6 weeks Viral Typical Duration Typical incubation clinical period presentation Norovirus 1-2 Days Hepatitis A 15-50 virus Days Assorted foods 12-60 Hr Gastroenteriti Under s cooked shellfish Weeksmonths Hepatitis Produce, undercooked shellfish 25 Parasitic Typical incubation Duration Typical clinical presentation Assorted foods Cryptos poridium parvum 2-10 Days Weeks Gastroenteritis Produce, water Cyclospora cayetanesis 1-11 Days Weeks Gastroenteritis Produce, water Toxoplasma gondii 5-23 Days Months Influenza-like illness, Food contaminated by cat feces, lymphadenopathy undercooked meat Giardia lamblia 1-4 Wk Weeks Gastroenteritis Water Taenia solium Variable Variable Asymptomatic, cysticercosis Raw pork 26 Important Microbial Causes of Food Poisoning Toxin related A. Staphylococcus aureus 24hourFlu? : incubation period < 6 hours An intoxication Not infection Clinical Features: appear 1-6 hours after ingestion and include vomiting (V), diarrhea (D), and intense abdominal pain/cramping (AB), usually no fever -last approximately 24 hours Source: infected human & food handlers Food contaminated -- enterotoxin produced-toxin is heat stable Diagnosis 1-epidemiological 2-isolating organism from suspected food 3- toxin detection in feacesof patient Treatment –none . supportive 27 S.aureus 28 B- Bacillus cereus (from rice meals) Bacillus caereus is an spore forming aerobic bacillus produces two types of enterotoxins. a- Heat stable causing: emetic type of food poisoning incubation period < 6 hours vomiting, nausea b- Heat labile causing: diarrheal type incubation period 6-24 hours “BOTH TOXINS ARE PREFORMED IN FOOD” 29 Clostridium Perfringens Causative agent: type A strains of C. perfringens (C. Welchii) Gram positive anaerobic rod spore forming characterized by sudden: Onset of colic Diarrhea Nausea Pathogenesis Incubation period 10-16 hours Spore-vegetate in food, when swollen they sporulate in the intestine and Produce toxin Diagnosis: Detection of spores in food >105 spores Detection of spore in faeces >106 spores 30 Botulism: Clostridium botulinum •Gram positive anaerobic spore forming It produces a powerful toxin The most lethal (killing toxin) 3 Kg can kill the whole population of the world. Foods associated: home canned “low acid” vegetables, honey Pathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin. Classified into A – G strains they produce the responsible toxins A, B, E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular junction leading to flaccid paralysis. Symptoms:12-72 hours after ingestion neurological blurred vision, and descending muscle weakness-flaccid paralysis • Treatment: antitoxin not antibiotics 31 Campylobacter jejuni General characteristics: gram negative curved rod, microaerophile, one or two polar flagella, no capsule Special culture to grow:, 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk, -undercooked poultry (shwarma)- may be found at a concentration of 109cells/gram of chicken Incubation period: 2-5 days • Symptoms: Person to person D (which may be bloody), AB,fever (1040C), vomiting uncommon – Last 2-10 days – Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis : Gram stain of feaces shows spiral organisms Treatment: none, mostly supportive care -some cases require antibiotics (erythromycin, quinolones) 32 Listeriosis Causative agent Listeria monocytogenes Gram positive rod aerobic . Resembles dipththeroids Can multiply at lower temperature 4°C Sources Wide spread in dust, soil, water, sewage, vegetation, animals feeds, poultry, hot dogs,meat, fish, vegetable Diseases - Infects GI tract (usually few symptoms),penetrates mucosa & enters blood stream - Fourth leading cause of meningitis (perhaps 50% fatality ) -Pregnant women: crosses placenta and causes, febrile illness abscess in fetal tissue miscarriage or stillbirth (60 %) - Neonates – meningitis - Immunocompromised patients – febrile illness 33 Salmonella General characteristics: gram negative rod, facultative anaerobe, peritrichous flagella Caused by No typhoid causing Salmonellas. (Called Food poisoning gastro intestinal Salmonellas.) Causes about 85% of cases of Food poisoning or Food borne diseases (Shawrma) Sources • Raw poultry and eggs • Raw milk • Raw beef • Unwashed fruit, alfalfa sprouts • Reptile pets: Snakes, turtles, lizards Part of the normal flora of poultry, reptiles Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection 34 Salmonella Culture: isolate and identify lactose negative & H2S positive Incubation time: 12-36 hours Symptoms: include D, AB, and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx. 2-4 million cases/year, only 40-50,000 are actually reported Salmonella typhimurium and enteritidis: – Most common serovars in USA – Antibiotics not advised due to increasing resistance (due to widespread addition of antibiotics to animal feed) – Do Not treat gastroenteritis unless invades tissues 35 Shigella General characteristics: gram negativerod facultative anaerobe, lactose negative • Only found in the feces of other humans • Organisms transmitted by the five F’s -food, fingers, feces, flies, and fomites Shigellosis or bacillary dysentery Incubation time: 24-48 hours – Only need 10 cells to cause infection; not affected by stomach acid • Symptoms: F, AB, D (may contain blood and mucus) • See passage of small volume bloodystools (20/day) 36 Shigella • S. sonnei-most common species in US, responsible; relatively mild; may cause some of traveler’s diarrhea • S. dysenteriae-causes more serious infection dysentery -due to the production of a Shiga toxin (A-B toxin) -in tropical areas-death rate up to 20% 37 Dysentery • Shigella dysenteriae – Virulent strains have plasmids to attach to epi cells of intestine; membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue; also has mechanism that allows to spread from cell to cell; sloughed areas of epis leads to intenseinflammation, pus, and bleeding – Rarely invades blood – Toxin strongly associated with hemolytic uremic syndrone; RBCs break in tiny blood vessels leading to anemia and kidney damage 38 Salmonella Shigella 39 Cholera Curved gram negative rod, facultative anaerobe single polar flagella • Can exist in saltwater for extended periods of time; tolerates high pH and high salt concentrations • Killed by stomach acid so need large numbers of organisms to cause infection Incubation time: several hours to days • Symptoms: “rice water stools”, suddenonset of explosive watery diarrhea (up to20 liters/day) with vomiting and pain • Cholera toxin is the key pathogenic feature – A-B toxin causes activation on enzyme that causes cells to continuously secrete chlorideions and electrolytes and H2O watery diarrhea 40 Non-cholera Vibrios • V. parahemolyticus: halophilic (requires sodium); Inhabits coastal salt waters; usually transmitted by raw or undercooked shellfish; less severe gastroenteritis • V. vulnificus: halophilic (requires 1% NaCl); wound infections—minor skin infection in coastal waterrapid sread through tissuespossible amputation – Fatal specticemia in 50% of patients with liver disease 41 Escherichia coli • Normal bowel flora • Strains that cause GI disease have virulence factors (coded by plasmids) – Enterotoxin production – Abiltiy to adhere to small intestin Diarrhea causing E. coli: Classified according to virulence – Entertoxigenic E. coli (ETEC) – Enterpathogenic E. coli (EPEC) – Enterohemorrhagic E. coli (EHEC) – Enteroinvasive E. coli (EIEC) 42 Entertoxigenic E. coli (ETEC)Enterpathogenic E. coli (EPEC) • Also known as traveler’s diarrhea • Attacks the small intestine •Two Enterotoxins promote • In developing countries the pumping of Cl- and accounts for 20%of inhibition of NaCl which diarrhea in bottle-fed results in diarrhea infants – Profuse watery stools • Attaches to mucosa of small intestine and causes cell • No invasion surface changes • Can develop immunity (loss of microvilli) • Prevent with bismuth (Pepto-Bismol) 43 Enteroinvasive E .Coli (EIEC) • Invades lining Of large intestine causing necrosis, inflammation, and ulceration of large bowel Enterohemorrhagic E. coli (EHEC) • Obtain from the consumption of animal products • Small dose (< 100 bacteria) to infect • Attacks the colon Shiga like toxin and • Usually seen in children • Produces lesion; inflammation and inn areas with poor bleeding (hemorrhagic sanitation colitis) • O157:H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome • Sorbitol negative MacConkeys used to isolate; culture all bloody diarrhea 44 Yersinia enterocolitica • Gram negative rod; lactose negative; grows at 4⁰C • Inhabits domestic animals (contaminates meat and milk) • Fever, diarrhea, abdominal pain • Can invade mucosa and spread to lymphatics (may present as appendicitis) • 45 Food Poisoning Outbreaks: 1.Illness in a period of time - few hours, few weeks. 2.In individuals who consumed common food. 3.Many acute cases can happen 4.Proper evaluation of cases and implicated food is essential 5.Single cases are difficult to recognized unless they have a distinctive clinical syndrome e.g. Botulism 46 LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKS 1- Type of Food 2-Incubation period 3-Isolation of the causative agent from a- Patient faeces, Vomit b- From incriminated food and related articles. 4- Investigation of Food Handlers in the same way. 47 LABORATORY INVESTIGATIONS OF FOOD HANDLERS 1-Most Important to explain the procedure 2-Don’t frightened the food handlers 3-Look for Salmonellae, Giardia, Amebae 4-Stop work until three specimens are negative 48 Is it safe to eat? ‘Use by’ dates are used for perishable foods, e.g. cheese, milk ‘Best before’ dates are used for less perishable foods, e.g. canned baked beans, jar of jam and frozen fish fingers. 49 Where should these foods be stored? Different foods are stored in a variety of ways to keep them safe to eat for longer. Dry cupboard Refrigerator Freezer 50 © British Nutrition Foundation 2003 Raw and cooked foods Raw meat and poultry should be stored on the bottom shelf of the fridge to prevent crosscontamination. 51 © British Nutrition Foundation 2003 Fruit and vegetables Always wash fruit and vegetables before you eat or use them to cook. This removes dirt and other and other particles. 52 © British Nutrition Foundation 2003 Prevention Cook: Cook to Proper Temperatures use a food thermometer to check ttemperature of food that you cook Chill: Refrigerate Promptly keepcoldfoods cold! Divide large amounts of food for quick cooling in the refrig Clean: Wash Hands and Surfaces Often - plain soap and plenty of water, scrubbing for 20 seconds Separate: Prevent Cross Contamination – keep raw and readyto-eat foods away from raw meat Store: Store Foods Properly – check package labels for use-by dates 53 54 THANK YOU 55 56 57 58