1/26/2016 Structure and Function of the Microbes Digestive System Learning Objective Invisible Invaders Name the structures of the digestive Amazing Allies system that contact food. CASE Chapter 25 Microbial Diseases of the Digestive System Microbial diseases are transmitted via the fecal-oral Structure and Function of the Digestive cycle System -disease results from ingesting food or water contaminated with pathogens Gastrointestinal(GI)tract or alimentary canal Pathogens enter food or water via fecal matter -Mouth Sanitation disrupts this cycle -Pharynx(throat) Need for new tests that reliably detect pathogens in -Esophagus food -Stomach CDC estimates-76 million cases of foodborne -Small and large intestine disease resulting in 5000 deaths annually in the US Accessory structures As more of our fruits and vegetables are grown in -Teeth and tongue itationis Salivary glands sa -Liver Gallbladder -Pancreas 2
1/26/2016 1 Invisible Invaders Amazing Allies Chapter 25 Microbial Diseases of the Digestive System • Microbial diseases are transmitted via the fecal-oral cycle – disease results from ingesting food or water contaminated with pathogens – Pathogens enter food or water via fecal matter • Sanitation disrupts this cycle • Need for new tests that reliably detect pathogens in food • CDC estimates – 76 million cases of foodborne disease resulting in 5000 deaths annually in the US • As more of our fruits and vegetables are grown in countries where sanitation is poor, an increase in foodborne disease is expected. Structure and Function of the Digestive System Learning Objective Name the structures of the digestive system that contact food. Structure and Function of the Digestive System • Gastrointestinal (GI) tract or alimentary canal – M th ou – Pharynx (throat) – Esophagus – Stomach – Small and large intestine • Accessory structures – Teeth and tongue – Salivary glands – Liver – Gallbladder – Pancreas
1/26/2016 The human digestive system Normal Microbiota of the Digestive Parotid (salivary) Oral cavity System gland Pharynx Learning Objective Esophagus Identify parts of the gastrointestinal tract that normally have microbiota. Liver Gallbladder ach Duodenum Pancrea Small intestine Large intestine Rectu Anus Structure and Function of the Digestive Normal Microbiota of the Digestive System System Millions of bacteria per ml of saliva Main function:breakdown of food into small Few microorganisms in the stomach molecules that are taken up -Due to HCl production ·Absorption of foods Small intestine also has few bacterio -25 tons of food pass through the GI tract in a lifetime -Rapid movement of food -Intestinal gas:swallowed N2 and microbial produced H2, -Paneth cells COz,and CHa Granule-filled phagocytic cells 80%of the immune system is located in the Produce defensins and lysozyme intestinal tract Large numbers of bacteria in the large -Gut-associated lymphoid tissue(GALT) intestine ·Lymph rodes -Anaerobes and facultative anaerobes ·Peyer's patches -Assist in enzymatic breakdown of food 100 billion (101)bacteria per gram of feces 2
1/26/2016 2 Parotid (salivary) gland Pharynx Oral cavity Tongue Teeth The human digestive system Esophagus Liver Gallbladder Stomach Duodenum Pancreas Small intestine Large intestine Anus Rectum Structure and Function of the Digestive System • Main function: breakdown of food into small molecules that are taken up • Absorption of foods – 25 tons of food pass through the GI tract in a lifetime – Intestinal gas: swallowed N2 and microbial produced H2, CO2, and CH4 • 80% of the immune system is located in the i t sti l t t intestinal tract – Gut-associated lymphoid tissue (GALT) • Lymph nodes • Peyer's patches Normal Microbiota of the Digestive System Learning Objective Identify parts of the gastrointestinal tract that normally have microbiota. Normal Microbiota of the Digestive System • Millions of bacteria per ml of saliva • Few microorganisms in the stomach – Due to HCl production • Small intestine also has few bacteria – Rapid movement of food – Paneth cells • Granule-filled phagocytic cells • Produce defensins and lysozyme • Large numbers of bacteria in the large intestine – Anaerobes and facultative anaerobes – Assist in enzymatic breakdown of food • 100 billion (1011) bacteria per gram of feces
1/26/2016 Bacterial Diseases of the Mouth Dental Caries(Tooth Decay) ·Dental plaque Learning Objective -Biofilms involved in the formation of dental caries Describe the events that lead to dental 700 species of bacteria in the oral cavity caries and periodontal disease. -Streptococcus mutans is the most important cariogenic organism Gram-positive coccus;falcultative anoerobe Converts sucrose to lactic acid which attacks the tooth enamel Produces dextran,a polysaccharide that forms plaque Plagues attract other cariogenic bacteria -Mainly,Streptococci:filamentous Actinomyces -But may harbor over 400 bacterial species A healthy human tooth Streptococcus mutans -Enamel Crowr -Dentin -Pulp cavity Gingival crevice Gum (gingiva) Periodontal ligament Bone Root Cementum Root canal Blood vessels and nerves in pulp Glucose broth Sucrose broth cavity
1/26/2016 3 Bacterial Diseases of the Mouth Learning Objective Describe the events that lead to dental caries and periodontal disease. A healthy human tooth Crown Enamel Dentin Pulp cavity Neck Root Gingival crevice Gum (gingiva) Periodontal ligament Bone Cementum Root canal Blood vessels and nerves in pulp cavity Dental Caries (Tooth Decay) • Dental plaque – Biofilms involved in the formation of dental caries • 700 species of bacteria in the oral cavity – Streptococcus mutans is the most important cariogenic organism • Gram-positive coccus; falcultative anaerobe • Converts sucrose to lactic acid which attacks the tooth enamel • Produces dextran, a polysaccharide that forms plaque • Plaques attract other cariogenic bacteria – Mainly, Streptococci; filamentous Actinomyces – But may harbor over 400 bacterial species Streptococcus mutans Glucose broth Sucrose broth
1/26/2016 Dental Caries (Tooth Decay) Periodontal Disease Caries penetrate from enamel into the Gingivitis dentin -Inflammation and infection of the gums -Half of the adult population has experienced this Appears in a few weeks if brushing is stopped -Caused by streptococci,actinomycetes,and anaerobic Decay can reach pulp,which contains the gram-negative bacteria blood supply and nerve cells ·Periodontitis -May advance to the soft tissues,leading to ahscesses Introduction of table sugar in the diet is -Caused by Porphyromonas correlated with the level of dental caries Acute necrotizing ulcerative gingivitis (trench mouth) -Coused by Prevotella intermedia The stages of tooth decay The stages of periodontal disease Advanced decay Plague is not permeable to saliva and lactic acid produced is not diluted or neutralized. Acid production results in softening of the eramel,which is low in fluoride and is more susceptible to the acid
1/26/2016 4 Dental Caries (Tooth Decay) • Caries penetrate from enamel into the dentin – Caused by gram-positive rods and filamentous bacteria • Decay can reach pulp, which contains the blood supply and nerve cells – May advance to the soft tissues, leading to a c bs esses • Introduction of table sugar in the diet is correlated with the level of dental caries The stages of tooth decay Enamel Dentin P l Plaque Decay Root canal therapy Healthy tooth with plaque Decay in enamel Advanced decay Decay in dentin Decay in pulp Pulp Bone Root plaque • Plaque is not permeable to saliva and lactic acid produced is not diluted or neutralized. • Acid production results in softening of the enamel, which is low in fluoride and is more susceptible to the acid Periodontal Disease • Gingivitis – Inflammation and infection of the gums – Half of the adult population has experienced this – Appears in a few weeks if brushing is stopped – Caused by streptococci, actinomycetes, and anaerobic gram-negative bacteria • Periodontitis – Bone and tissue supporting the teeth are destroyed – Caused by Porphyromonas • Acute necrotizing ulcerative gingivitis (trench mouth) – Caused by Prevotella intermedia The stages of periodontal disease Plaque Tooth Gum (gingiva) Bone Cementum Periodontal ligament Healthy Gingivitis Periodontal Periodontitis q ligament Healthy gingivae Gingivitis Periodontal pockets Periodontitis
1/26/2016 Bacterial Diseases of the Lower Digestive System Dysentery-diarrhea accompanied with blood or mucus Learning Objective Gastroenteritis -inflammation of the List the causative agents,suspect foods, stomach and intestinal mucosa signs and symptoms,and treatments for .In developing countries,diarrhea is a staphylococcal food poisoning. shigellosis,salmonellosis,typhoid fever. major factor in infant mortality(1 out of cholera,gastroenteritis,and peptic 4 children die) ulcer disease. Disease of the digestive system are often related to food ingestion. Staphylococcal Food Poisoning Disease of the digestive system are of 2 types -infection (Staphylococcal Enterotoxicosis) -intoxication Enterotoxin produced by Staphylococcus aureus Infection occurs when a pathogen enters the GI -Serological type A tract and multiplies Coagulates blood plasma -grow in the mucosa or penetrate to other organs -Toxin is not killed by boiling -GIdisturbance is delayed while bacteria multiply fever usually occur S.aureus inhabits nasal passages Intoxication is due to ingestion of a toxin Toxins produced when the organism -sudden appearance:no fever is allowed to incubate in food (temperature Both type es are associated with abdominal cramps, abuse) nausea,diarrhea,and vomiting -s aureus outo Diarrhea and vomiting are designed to rid the body of the harmful substance. Phage typing traces sources of contamination
1/26/2016 5 Bacterial Diseases of the Lower Digestive System Learning Objective List the causative agents, suspect foods, signs and symptoms, and treatments for staphylococcal food poisoning, shigellosis, salmonellosis, typhoid fever, ch l st t itis d ti h olera, gastroen teritis, and pepti c ulcer disease. • Disease of the digestive system are of 2 types – infection – intoxication • Infection occurs when a pathogen enters the GI tract d l i li and multiplies – grow in the mucosa or penetrate to other organs – GI disturbance is delayed while bacteria multiply; fever usually occurs • Intoxication is due to ingestion of a toxin – sudden app ; f earance; no fever • Both types are associated with abdominal cramps, nausea, diarrhea, and vomiting • Diarrhea and vomiting are designed to rid the body of the harmful substance. • Dysentery – diarrhea accompanied with blood or mucus • Gastroenteritis – inflammation of the stomach and intestinal mucosa • In developing countries, diarrhea is a major factor in infant mortality (1 out of 4 children die) • Disease of the digestive system are often related to food ingestion. Staphylococcal Food Poisoning (Staphylococcal Enterotoxicosis) • Enterotoxin produced by Staphylococcus aureus – Serological type A • C l t bl d l Coagulates blood plasma – Toxin is not killed by boiling • S. aureus inhabits nasal passages • Toxins produced when the organism is allowed to incubate in food (tem perature abuse) – S. aureus outgrows most bacteria in high osmotic pressure and high temperature (600C for 30 mins) • Phage typing traces sources of contamination
1/26/2016 Sequence of events in Shigellosis a typical outbreak of staphylococcal food poisoning Refrigeration is oge6 e恤cd best preventive methods okhaanga cells.thus avoiding immune defenses. nlegtosaoen rarely hrs.eaon Mucosal abscess Shigellosis(Bacillary Dysentery) Salmonellosis (Salmonella Gastroenteritis) Infection caused by the genus Shigella -Facultatively anaerabic:gram-negative:four species ·Salmonella enterica -Up to 20 bowel movements in one day -Gram-negative,facultative anaerobe, -12 h to 2 weeks incubation time nonendospore-forming rods Only spread from person to person:no animal -Normal inhabitant of the human intestinal tract reservoir -2000 serotypes .Produces the Shiga toxin (inhibits protein synthesis) Small infectious dose Invades intestinal mucosa and multiplies -Attaches to M cells,irvades,and spreads to other cells -Passes through M cells and enters the lymphatics Damage to the intestinal wall -Replicates in macrophages Can invade the bloodstream Incubation of 12 to 36 hours:fever,nausea, CDC estimates 450,000 cases annually:no vaccine yet pain and cramps,diarrhea Treated with fluoroguinolones and oral rehydration 6
1/26/2016 6 Sequence of events in a typical outbreak of staphylococcal food poisoning Refrigeration is best preventive methods Shigellosis (Bacillary Dysentery) • Infection caused by the genus Shigella – Facultatively anaerobic; gram-negative; four species – Up to 20 bowel movements in one day – 12 h to 2 weeks incubation time • Only spread from person to person; no animal reservoir • Produces the Shiga toxin (inhibits protein synthesis) • Small infectious dose – A h M ll i d d d h ll Attaches to M cells, invades, and spreads to other cells • Damage to the intestinal wall • Can invade the bloodstream • CDC estimates 450,000 cases annually; no vaccine yet • Treated with fluoroquinolones and oral rehydration Shigella Shigellosis M cell Epithelial cell lining intestinal tract Membrane ruffle Shigella enters an epithelial cell. Shigella multiplies inside the cell. Shigella invades neig gp hboring epithelial cells, thus avoiding immune defenses. An abscess forms as epithelial cells are killed by the infection. The bacteria rarely spread in the bloodstream. Mucosal abscess Salmonellosis (Salmonella Gastroenteritis) • Salmonella enterica – Gram-neg, , ative, facultative anaerobe, nonendospore-forming rods – Normal inhabitant of the human intestinal tract – 2000 serotypes • Invades intestinal mucosa and multiplies – Passes through M cells and enters the lymphatics – Replicates in macrophages • Incubation of 12 to 36 hours; fever, nausea, pain and cramps, diarrhea
1/26/2016 M cell Salmonellosis Typhoid Fever _Epithelial cell lining the Caused by Salmonella typhi intestinal tract Membrane ruffle 一Most virulent serotype ofmn恤 650 -Spread only by human feces Sa/monella enters an epithelial cell. -Rare in the United States today due to sanitation -Globally,21 million cases annually leading to tens of thousands of deaths Bacteria spread throughout the body in phagocytes -Releases organism into the bloodstream(spleen and liver) 68 the i High fever,headache,intestinal wall ulceration 1-3%of patients become chronic carriers -Harbor the organism in the gallbladder(Typhoid Mary) Lymph node Treated with chloramphenicol,quinolones,or Bloodstream cephalosporins Salmonellosis (Sa/mone/la Gastroenteritis) The incidence of salmonellosis and typhoid fever 30 1.4 million cases:shed from feces for 6 months ·4o0 deaths annually Associated with commercial chicken and egg 20 production -Hens are susceptible to infection -Bacteria survive in the albumin,which contains Typhoid fever -Caution for raw egg consumption -1 in 20,000 eggs are contaminated Bacterial source:intestines of many animals 440465258847076828940006“12 Diagnosed directly from the stool or by PCR Treatment with oral rehydration therapy
1/26/2016 7 Salmonella Salmonellosis Epithelial cell lining the intestinal tract M cell Membrane ruffle Salmonella enters an epithelial cell. Salmonella multiplies within a vesicle inside the cell. Salmonella multiplies in mucosal cells; th h fl here the inflammatory response l resu ts in diarrhea. Occasionally, the bacteria cross the epithelial cell membrane and enter the lymphatic system and bloodstream. Lymph node Bloodstream Salmonellosis (Salmonella Gastroenteritis) • 1.4 million cases; shed from feces for 6 months • 400 deaths annually • Associated with commercial chicken and egg production – Hens are susceptible to infection – Bacteria survive in the albumin, which contains antibacterials such as lysozyme and lactoferrin – Caution for raw egg p consumption – 1 in 20,000 eggs are contaminated • Bacterial source: intestines of many animals • Diagnosed directly from the stool or by PCR • Treatment with oral rehydration therapy Typhoid Fever • Caused by Salmonella typhi – Most virulent serotype of Salmonella – Spread only by human feces – R iare n th U it d St t the United States t d d t it ti today due to sanitation – Globally, 21 million cases annually leading to tens of thousands of deaths • Bacteria spread throughout the body in phagocytes – Releases organism into the bloodstream (spleen and liver) • Hi h f h d h i t ti l ll l ti High fever, headache, intestinal wall ulceration • 1–3% of patients become chronic carriers – Harbor the organism in the gallbladder (Typhoid Mary) • Treated with chloramphenicol, quinolones, or cephalosporins The incidence of salmonellosis and typhoid fever
1/26/2016 Cholera Caused by Vibrio cholerae -Slightly curved,gram-negative rod with single polar flagellum -Associated with salty waters -Produces the cholera toxin Toxin causes the host cells to secrete electrolytes and water Lysogenic bacteriophage carries the toxin .(mucus epithelial cell) Can lose 12 to 20 liters of fluid per day -Causes shock,collapse,organ failure,and death Treatment includes IV fluid replacement Cholera after Natural Disasters Cholera after Natural Disasters Cholera increases when sanitation and sewage disposal systems are Strategies for disaster preparedness compromised -Oral rehydration solutions ·Sat,sugar,and water 。 Outbreak in Haiti after earthquake due -Stockpiling vaccines to deficient septic system at the Nepalese base The ultimate solution -Nepalese soldiers were part of the United -Proper sanitation,water storage Nations peacekeeping force handwashing
1/26/2016 8 Cholera • Caused by Vibrio cholerae – Slightly curved, gram-negative rod with single polar flagellum – Associated with salty waters – Produces the cholera toxin • Toxin causes the host cells to secrete electrolytes and water • Lysogenic bacteriophage carries the toxin • Causes rice water stools (mucus "rice water stools“ (mucus-epithelial cells) • Can lose 12 to 20 liters of fluid per day – Causes shock, collapse, organ failure, and death • Treatment includes IV fluid replacement Cholera after Natural Disasters • Cholera increases when sanitation and sewag p ym e disposal systems are compromised • Outbreak in Haiti after earthquake due to deficient septic system at the Nepalese base – Nepalese soldiers were part of the United Nations peacekeeping force Cholera after Natural Disasters • Strategies for disaster preparedness – O l h d l Oral rehydration solutions • Salt, sugar, and water – Stockpiling vaccines • The ultimate solution – Proper sanitation water storage Proper sanitation, water storage, handwashing
1/26/2016 Noncholera Vibrios Enterohemorrhagic E.coli(EHEC) -Produces Shiga-like toxin Released upon the cell's lysis 11 other Vibrio species cause disease in -Most outbreaks are due to serotype 0157:H7 humans -Cattle are the main reservoir and unaffected Mostly adapted to salty coastal waters -Vibrio parahaemolyticus -Ingested food and petting zoos Found in saltwater estuaries -Infective dose is fewer than 100 bacteria Common cause of gastroenteritis ‘8GiRegrcadncnrmcmaorntodusth -Diagnosed by the inability to ferment sorbitol and pulsed-field gel electrophoresis Escherichia coli Gastroenteritis Enterotoxigenic E.coli(ETEC) Enteropathogenic E.coli(EPEC) -Secretes enterotoxins that cause diarrhea -Diarrhea in developing countries -Often fatal for children under 5 -One toxin resembles cholera toxin in function Enteroinvasive E.coli(EIEC) Causes Shige/la-like dysentery -Same pathogenic mechanism as Shigell Enteroaggregative E.coli(EAEC) -Only in humans -Produce an enterotoxin causing watery diarrhea
1/26/2016 9 Noncholera Vibrios • 11 other Vibrio species cause disease in humans • Mostly adapted to salty coastal waters – Vibrio parahaemolyticus • Found in saltwater estuaries • Common cause of gastroenteritis • Raw oysters and crustaceans are associated with outbreaks • Require early antibiotic therapy as these infections may be life-threatening Escherichia coli Gastroenteritis • Enteropathogenic E. coli (EPEC) – Diarrhea in developing countries – Secret effector proteins that are translocated into host cells – Causes the host cells to form pedestals where the bacteria attach • Enteroinvasive E. coli (EIEC) – Causes Shigella-like dysentery – Same pathogenic mechanism as Shigella • Enteroaggregative E. coli (EAEC) – Only in humans – Produce an enterotoxin causing watery diarrhea • Enterohemorrhagic E. coli (EHEC) – Produces Shiga-like toxin • Released upon the cell's lysis – Most outbreaks are due to serotype O157:H7 – Cattle are the main reservoir and unaffected – Ingested food and petting zoos – Infective dose is fewer than 100 bacteria – Causes hemorrhagic colitis (inflammation of the colon with bleeding) and hemolytic uremic syndrome (blood in the urine) – 5% mortality in children; kidney transplants may be needed – Diagnosed by the inability to ferment sorbitol and pulsed-field gel electrophoresis • Enterotoxigenic E. coli (ETEC) – Secretes enterotoxins that cause diarrhea – Often fatal for children under 5 – One toxin resembles cholera toxin in function
1/26/2016 Traveler's Diarrhea Helicobacter Peptic Ulcer Disease Caused by Helicobacter pylori Most common cause is ETEC -Infects 30-50%of the population in the developed world Second most common cause is EAEC -Grows in the stomach acid by producing urease Can also be caused by Salmone/la, Converts urea to alkaline ammonia Shigella,and Campylobacter -Disrupts stomach mucosa,causing inflammation Oral rehydration therapy and bismuth- Treated with antimicrobial drugs and containing preparations bismuth subsalicylate Diagnostic test requires a biopsy,culture, antigen detection in stools,and urea breath test Campylobacter Gastroenteritis Helicobacter pylori leads to ulcers in the stomach wall Urease pr ea.The Caused by Campylobacter jejuni neutralizes hydrochloric acid of stomach.(NH,+HClNH,CI) -Gram-negative,microaerophilic,spirally curv Leading cause of foodborne illness in US Helicobacter pylori -Common in the intestines of poultry -Contaminates almost all chicken 60%of cattle excrete organism in feces and milk -Do not replicate in food Fever.cramping,abdominal pain,diarrhea dysentery 2 million cases annually in the US 1 in 1000 cases leads to a neurological disorder Guillain-Barre syndrome,a temporary paralysis cells 0
1/26/2016 10 Traveler's Diarrhea • Most common cause is ETEC • Second most common cause is EAEC • Can also be caused by Salmonella, Shigella, and Campylobacter • Oral rehydration therapy and bismuthcontaining preparations Campylobacter Gastroenteritis • Caused by Campylobacter jejuni – Gram-negative, microaerophilic, spirally curved • Leading cause of foodborne illness in US – Common in the intestines of poultry – Contaminates almost all chicken – 60% of cattle excrete organism in feces and milk – Do not replicate in food • Fever cramping abdominal pain diarrhea Fever, cramping, abdominal pain, diarrhea, dysentery • 2 million cases annually in the US • 1 in 1000 cases leads to a neurological disorder Guillain-Barré syndrome, a temporary paralysis Helicobacter Peptic Ulcer Disease • Caused by Helicobacter pylori – Infects 30–50% of the population in the developed world – Grows in the stomach acid by producing urease • Converts urea to alkaline ammonia – Disrupts stomach mucosa, causing inflammation • Treated with antimicrobial drugs and bismuth subsalicylate • Diagnostic test requires a biopsy, culture, antigen detection in stools, and urea breath test Helicobacter pylori leads to ulcers in the stomach wall Mucus l r pr t cts Helicobacter pylori Urease produces alkaline ammonia from urea. The ammonia neutralizes hydrochloric acid of stomach. (NH3 + HCl ➝ NH4Cl) Mucus layer protects stomach from activity of gastric acid (HCl). Mucus layer Hydrochloric acid Mucus-secreting pith li l ll Plasma cell Lymphocyte Neutrophil Blood capillary (cross section) Submucosal cells Connective tissue epithelial cells lining stomach