1. Chapter 11 Foodborne and Waterborne Bacterial Diseases

2. 11.1 The Structure and Indigenous Microbiota of the Digestive System The digestive system is composed of two separate categories of organs. Gastrointestinal (GI) tract Accessory digestive organs Chemical, mechanical, and cellular defenses protect the GI tract from pathogen colonization. Figure 03: The Human Digestive System

3. The human intestinal microbiome has not been well studied. NIH has launched the Human Microbiome Project to learn more about our gut microbiome. Figure 05: Microbiota of the Digestive System

4. The microbiota of mouth and large intestine represent extremely complex communities Oral diseases cause pain and disability for affected individuals. 50-100 million bacterial cells inhabit the human mouth. 11.2 Bacterial Diseases of the Oral Cavity Figure 06A: The Anatomy of a Tooth

5. Plaque is a biofilm, containing salivary proteins, food debris and bacterial cells and products. Dental caries (tooth decay) results from: plaque building. dietary carbohydrates. acidogenic bacteria. Figure 06B: The Anatomy of a Tooth © BSIP/Photo Researchers, Inc.

6. A major cause of dental caries is Streptococcus mutans. They ferment dietary carbohydrates into acids. Fluoride and diet can prevent dental caries. FIGURE 7: Dental caries © Dr. Tony Brain/Photo Researchers, Inc. FIGURE 8a: Dental plaque

7. Periodontal disease can arise from bacteria in dental plaque. Poor oral hygiene leads to increased subgingival plaque, which can be populated by bacteria. It is characterized by: –ulcers and bleeding along the gingival margin. –degradation of periodontal ligaments and bone. –loosened or lost teeth. © SPL/Photo Researchers, Inc. FIGURE 9B: Periodontal disease

8. 11.3 Introduction to Bacterial Diseases of the GI Tract Many foodborne and waterborne diseases have a bacterial cause. Intoxications are illnesses in which bacterial toxins are ingested with food and water. Infections are illnesses in which live bacterial pathogens are ingested and grow in the body. The incubation period is the time between: consumption of contaminated material. appearance of symptoms.

9. Clinical symptoms and duration of illness depend on: the toxin or microbe. the infectious dose. Demographics can make individuals more or less prone to food/waterborne illness. For example, age or sanitary conditions

10. There are several ways foods or water become contaminated. Meat can be infected during improper slaughter procedure. Fruits and vegetables can be washed with contaminated water. Infected humans can contaminate food they handle through the fecal-oral route.

11. Cross-contamination can occur: between foods via knife, cutting board, etc. Water contamination can occur by defecation of infected individuals in public water sources Improperly stored foods can contain large numbers of pathogens because of rapid multiplication FIGURE 10: Source of foodborne illness Data from CDC

12. Food poisoning illnesses are the result of enterotoxins. Staphylococcus aureus causes staphylococcal food poisoning. Toxins are often consumed in protein-rich foods such as: –meat and fish. –dairy products. The enterotoxin causes gastroenteritis for several hours. 11.4 Foodborne Intoxications Caused by Bacteria © Dr. Gary Gaugler/Visuals Unlimited FIGURE 11A: Staphylococcus aureus SEM

13. Food is often contaminated by: boils or abscesses on a handler’s skin. through sneezing. Proper handling, refrigeration, and heating help decrease the risk of contamination. FIGURE 11B: Staphylococcus aureus typing Courtesy of Paul Gulig, Donna Duckworth and Julio Martin, University of Florida

14. Clostridium perfringens causes clostridial food poisoning. C. perfringens commonly contaminated meat, poultry, and fish. Clinical symptoms require a high infectious dose and take 8–24 hours to appear. Bacillus cereus can cause diarrhea or vomiting. Infections usually occur from eating contaminated cooked grains. © CNRI/Photo Researchers, Inc. FIGURE 12: Clostridium perfringens TEM

15. Clostridium botulinum causes the most dangerous foodborne intoxication. Botulism is caused by a neurotoxin that inhibits the release of the neurotransmitter acetylcholine preventing the contraction of muscles causing flaccid paralysis and respiratory arrest. Treated by antitoxins and life-support systems like ventilators. Prevented by heating foods before eating them for at least 10 minutes.

16. Other forms of botulism Wound botulism occurs when toxins are produced in anaerobic tissue of wounds. Infant botulism is the most common form of botulism in the US. It occurs when infants ingest endospores, commonly with honey causing floppy baby syndrome. They are treated by Penicillin. Botulinum toxins are used in Botox. Figure 13: Cosmetic Injection of Botulinum Toxin. © Michael N. Paras/age fotostock

17. 11.5 Foodborne and Waterborne Infections Bacterial GI infections have a longer incubation period than intoxications because bacterial cells must establish themselves in the body after ingestion. Bacterial gastroenteritis often produces an inflammatory condition. Dehydration is a common but serious complication of gastroenteritis. FIGURE MF01: A computer enhanced barium enema X-ray © Scott Camazine/Alamy Images

18. Cholera can involve enormous fluid loss. Cholera is caused by Vibrio cholerae. V. cholerae are often consumed with raw oysters and water. The cells are susceptible to stomach acid. A large infectious dose is needed to colonize the intestines. Figure 14A: Cholera Disease Spread. © SAS/Alamy Images

19. Cholera toxin causes unrelenting loss of fluid and electrolytes through diarrhea (up to 1 L/hour). If untreated, fluid loss thickens the blood, leading to shock and coma. Antibiotics and restoration of water and electrolyte balance are effective in treatment. Vaccines using dead V. cholerae are available. Preventable by clean water and food. FIGURE 14 B: Spread of cholera Figure MM05: Vibrio cholerae.

20. Healthcare-associated infections Clostridium difficile Major cause of pseudomembranous colitis © David M. Martin, M.D./Photo Researchers, Inc. FIGURE 16: Pseudomembranous colitis

21. Listeria monocytogenes causes listeriosis through fecal contaminated food, water and milk. It primarily affects pregnant women, newborns, elderly and the immunocompromised causing a form of meningitis. Brucella sp. cause brucellosis from contaminated animal products through a cut in the skin. This is called undulant fever. Both can be prevented by pasteurization. Vibrio sp. causes seafood borne gastroenteritis.

22. Several bacteria can cause an invasive gastroenteritis. Typhoid Fever involves a blood infection. It is caused by Salmonella enterica serotype Typhi (S. typhi). S. typhi is transmitted by the five Fs: Flies Food Fingers Feces Fomites It is acid resistant. It passes through the stomach to the small intestine. It causes ulcers, bleeding, and pain. Data from CDC, Summary of Notifiable Diseases, 2006. FIGURE 18: The incidence of typhoid fever

23. Salmonella serotypes are often found in unpasteurized milk or poultry products. Transmitted by the fecal oral route or they can also be transmitted by live animals. © Dr. John D. Cunningham/Visuals Unlimited FIGURE 19A: Salmonella enterica SEM

24. Shigellosis (bacterial dysentery) occurs where sanitary conditions are lacking. Shigellosis is primarily caused by Shigella sonnei S. dystenteriae causes epidemics in the developing world Contaminated foods commonly include eggs, vegetables, shellfish, dairy. Shiga toxin production in the intestinal epithelium triggers gastroenteritis. Infection of the large intestine can lead to fatal dysentery. No vaccine is available. Figure MM11: Shigella sonnei.

25. E. coli diarrheas cause various forms of gastroenteritis. Escherichia coli is normally found in the human intestine, but certain serotypes are pathogenic. Transmission occurs through the fecal-oral route. FIGURE 15: E. coli © Stephanie Schuller/Photo Researchers, Inc.

26. Enterotoxigenic E. coli (ETEC) penetrate the intestinal epithelium and produce a toxin that causes gastroenteritis. a.k.a. traveler’s diarrhea Enteropathogenic E. coli (EPEC) cause diarrhea in infants, particularly where sanitation is lacking. Courtesy of CDC FIGURE TC01: E. coli O157:H7 Figure MM06: Escherichia coli.

27. Campylobacteriosis results from consumption of contaminated poultry or dairy products. Campylobacteriosis is the most common cause of bacterial gastroenteritis in the United States Campylobacter jejuni is transmitted through the fecal-oral route, usually by poultry © David Scharf/Peter Arnold, Inc. FIGURE 21: Campylobacter jejuni TEM

28. Gastric ulcer disease can be spread person to person. Helicobacter pylori is involved in gastric ulcers. It is unknown how H. pylori is transmitted, but it likely involves contaminated food or water. © SPL/Photo Researchers, Inc. FIGURE MI11B: H. pylori organisms

29. The bacteria produce urease, which in turn produces ammonia. Ammonia neutralizes acid in that area of the stomach, allowing the bacteria to survive. The ammonia, and an H. pylori cytotoxin destroy mucous- secreting cells. This creates a sore. FIGURE 23: The progression of gastric ulcers © P. Hawtin/Photo Researchers, Inc.