GI System Diseases.pdf

Gastrointestinal System Diseases Structure and Function of the Digestive System Gastrointestinal (GI) tract or alimentary canal Mouth Pharynx (throat) Esophagus Stomach Small and large intestine Accessory structures Teeth and tongue Salivary glan...

Gastrointestinal System Diseases Structure and Function of the Digestive System Gastrointestinal (GI) tract or alimentary canal Mouth Pharynx (throat) Esophagus Stomach Small and large intestine Accessory structures Teeth and tongue Salivary glands Liver Gallbladder Pancreas Absorption of foods 25 tons of food pass through the GI tract in a lifetime Immunity of the Digestive System 80% of the immune system is located in the intestinal tract Lysozyme, immunoglobulins, and phagocytes in saliva and gingiva Washing, chewing and swallowing of saliva Mechanical action of peristalsis Gut-associated lymphoid tissue (GALT) Lymph nodes Peyer's patches IgA and Mucus Bacteriocins: toxins that attach to bacteria Normal Microbiota of the Digestive System Millions of bacteria per ml of saliva Aerobic and anaerobic coat all surfaces Few microorganisms in the stomach Due to HCl production Small intestine Paneth cells Granule-filled phagocytic cells; produce defensins Large numbers of bacteria in the large intestine Anaerobes and facultative anaerobes 100 billion bacteria per gram of feces Normal Microbiota of the Digestive System Esophagus, stomach, duodenum These regions are almost free of microbes Peristalsis and rapid transport of food prevents microbial colonization Tongue, teeth, jejunum, ileum, colon, rectum Viridans streptococci are most prevalent in this region Lower small intestine and colon Microbiota here are microbial antagonists Small intestine: Lactobacilli, Candida and diphtheriods Large intestine: Bacteriodetes, Firmicutes, Methanogenic archea and fungi Mucous membranes prevents entry of microbes into the bloodstream Diseases Bacterial: Fungal diseases: Dental caries Thrush Food poisonings Aflatoxin poisoning Cholera Ergot poisoning Gastroenteritis Protozoan diseases: Bacterial Dysentery Amebic dysentery Peptic Ulcers Giardiasis Viral diseases: Cryptosporidiosis Mumps Hepatitis A-E Bacterial Diseases of the Digestive System Dental Plaque A continuously formed coating (biofilm) of microorganisms and organic matter on tooth surfaces The first step in tooth decay and gum disease Plaque begins to form within 24 hours after cleaning Plaque formation begins as positively charged proteins in saliva adhere to negatively charged enamel Bacteria produce dextran, a gummy polysaccharide Streptococcus mutans and Streptococcus sanguis are responsible for forming plaque Dental Caries (Tooth Decay) The chemical dissolution of enamel and deeper parts of teeth The most common infectious disease in developing countries because of refined sugar in diet Unchecked, the decay can proceed through the enamel, into dentin, pulp cavity, and eventually cause an abscess in the bone supporting the tooth Causative agents: Streptococcus mutans → most common Lactobacillus ssp., and Actinomyces viscosus  Formation of Dental Caries Bacterial biofilms (plaque) develop on teeth Acids produced gradually dissolve the enamel, followed by the dentin. If left untreated, the lesion may reach the pulp and cause an abscess. (credit: modification of work by “BruceBlaus”/Wikimedia Commons)  Dental Caries Tartar (dental calculus) is visible at the bases of these teeth. The darker deposits higher on the crowns are staining. This tooth shows only a small amount of visible decay. An X-ray of the same tooth shows that there is a dark area representing more decay inside the tooth. Removal of a portion of the crown reveals the area of damage. All of the cavity must be removed before filling. (credit: modification of work by “DRosenbach”/Wikimedia Commons) Dental Caries Treatment Cavities are filled with amalgam or composite Prevention Fluoride Helps reduce the solubility of teeth The amount of fluoride that can be added to the diet or used topically is limited due to fluoride toxicity Reducing the amount of dietary sucrose Fissure sealants Periodontal Disease Affects over 80% of teenagers and adults The major cause of tooth loss Signs: Gum inflammation Erosion of periodontal ligaments and the bone supporting teeth Periodontal Disease Streptococci, Porphyromonas and Actinomyces Gingivitis: the mildest form of periodontal disease, which affects only the gums Caused by streptococci, actinomycetes, and anaerobic gram-negative bacteria Periodontitis: Untreated, gingivitis will progress to this Affects the bone and tissue supporting the teeth and gums Acute necrotizing ulcerative gingivitis: Trench mouth The most severe form of periodontal disease Caused by Prevotella species. Food Poisonings 76 million cases in the United States annually Majority are mild and self-limiting for a day or two More than 250 different foodborne diseases caused by all different types of microbes Foodborne diseases can be: Intoxications: caused by toxins (enterotoxins) Infections: requires microbe to multiply in the host The first symptoms are usually nausea, vomiting, abdominal cramps and diarrhea. Staphylococcal Food Poisoning Staphylococcus aureus Intoxication Grows in food and produces heat stable enterotoxins Egg products (custard, cream-filled desserts), Poultry, meat and meat products Carried on hands of food preparers Halotolerant Signs/Symptoms Gastroenteritis, nausea, vomiting and diarrhea in 1-6 h Refrigeration below 40°F reduces growth of Staphylococci Self limiting When toxin leaves the body, so do symptoms Keeping Food Safe Food Infection- EHEC E. coli O157:H7: O-Antigen is part of LPS, H is flagellin Pathogen that has a reservoir in cattle and other similar animals Produces a Shiga-like toxin which causes bloody diarrhea and alteration of the intestinal microvilli Acquired via transduction Severe disease: Bloody diarrhea and painful abdominal cramps, vomiting, no fever Hemolytic Uremic Syndrome: In 3% to 5% of cases, severe complications include temporary anemia, profuse bleeding, and kidney failure By Rainer Zenz - Own work Rainer Z... 14:24, 5 November 2016 (UTC), CC BY-SA 3.0, Other E. coli Infections ETEC: Enterotoxigenic E. coli Cholera-like toxin and adhesins Watery diarrhea EIEC: Enteroinvasive E. coli Invades intestinal epithelium through plasmid borne invasin gene Watery diarrhea EPEC: Enteropathogenic E. coli Potentially fatal in infants and developing countries Fever, vomiting, dehydration →severe Toxin forms pedestals on microvilli Salmonellosis Salmonella spp. are found in the intestines of birds, reptiles and mammals. Pathogen and virulence factors Caused by Salmonella enterica serotypes Serotypes typhi and paratyphi cause typhoid fever Serotypes enteritidis and typhimurium cause salmonellosis Bacteria tolerate acidity of stomach and pass to the intestine Toxins disrupt numerous cellular activities Pathogenesis and epidemiology Salmonellosis is often acquired by consuming contaminated eggs credit: modification of work by National Institutes for Health Other Kinds of Food Poisonings Clostridium botulinum Cyclospora cayetanensis Protozoan A diarrheal illness related to Guatemalan raspberries Contaminated in fields with this unusual parasite Vibrio parahemolyticus Contaminated oyster beds in Galveston Bay and caused an epidemic of diarrheal illness in persons eating raw oysters Makes hemolysin Vibrio vulnificus Oysters of the Pacific NW and elsewhere Can cause necrotizing fascitis Norovirus Calicivirus or Norwalk Virus Rarely diagnosed, because the laboratory test is not widely available. It causes an acute gastrointestinal illness, usually with more vomiting than diarrhea, that resolves within two days. It is believed that Norwalk-like viruses are transmitted from person to person Infected kitchen workers can contaminate a salad or sandwich as they prepare it, if they have the virus on their hands. By Rapidfire - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6303294 Rotavirus A major cause of infant morbidity and mortality in developing countries Accounts for 1/3 of childhood deaths in some countries Transmission: fecal-oral route Virus replicates in the intestine, damages the intestinal epithelium, and causes a watery diarrhea and vomiting within 48 hours Treatment: Self limiting Fluid replacement Prevention: sanitary practices, vaccine Rotateq By Dr Graham Beards, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=5535228 Food Poisonings Diagnosis: Laboratory tests that identify the causative organism (PCR) Culturing stool samples Examining stools under the microscope Treatment: For intoxications, usually none, but attempt to alleviate signs and symptoms Replacing the lost fluids and electrolytes Preparations of bismuth subsalicylate (e.g., Pepto-Bismol) can reduce the diarrhea. These medications should be avoided if there is high fever or blood in the stools because they may make the illness worse. For infections, might give antibiotics in addition to substances to alleviate signs and symptoms Food Poisonings- Prevention Cook food thoroughly. Avoid cross-contaminating foods. Wash hands, utensils, and cutting boards after contact with raw meat or poultry and before contacting other food. Refrigerate leftovers promptly if they are not going to be eaten within 4 hours. Wash produce in running tap water Wash hands before, during and after preparing food. Report suspected foodborne illnesses to local health department Bacillary Dysentery- Shigellosis S. dysenteriae, S. flexneri, S. boydii and S. sonnei Facultative anaerobe Transmission: Contaminated food, fingers, flies, feces, and fomites Signs/Symptoms: Include fever, irritability, drowsiness, weight loss, nausea, vomiting, diarrhea, and abdominal pain. Dysentery is rarely fatal in adults Can cause abcesses and tissue damage The infection may be self limiting Treatment: Flouroquinolones (Cipro) and fluid replacement Antibiotic resistance is spreading Cholera Acute, diarrheal illness resulting from infection of the intestine. The disease is still common today in India and Africa. Haiti post-earthquake Causative agent: Vibrio cholerae Gram negative, comma shaped Cholera V. cholerae produces an enterotoxin that binds to small intestine epithelia making membranes highly permeable to water. This results in secretion of fluids and Cl- ions and inhibition of Na+ absorption Transmission: Contaminated drinking water or food (shellfish, fruit, vegetables) Cholera Signs/Symptoms: Watery diarrhea (rice water stools), vomiting, and leg cramps Rapid loss of body fluids leads to dehydration and shock Skin becomes wrinkled, eyes sink inward, blood thickens, circulation decreases Without treatment, death can occur within hours. Treatment: Fluid and electrolyte replacement is the major concern. With prompt rehydration, fewer than 1% of cholera patients die. Antibiotics shorten the course and diminish the severity of the illness, but they are not as important as rehydration Oral Rehydration Solution 1 quart water ¾ teaspoon salt 6 teaspoons sugar Prevention: Boil water or treat it with chlorine. Thoroughly cook food Avoid uncooked foods such as raw fish, fruits and vegetables Vaccine: vaccine is not available in the United States Gastric Ulcers Causative agent: Helicobacter pylori Helicobacter pylori was first cultured in 1982 from gastric biopsy tissues Prior to this it was believed stress caused ulcers Transmission: unknown Formation of gastric ulcers H. pylori is present in 95% of patients with duodenal ulcers and 70% of patients with gastric ulcers. H. pylori colonizes and multiplies in the gastric mucosa directly above the epithelial cell layer of the stomach This will lead to destruction of the epithelia resulting in an ulceration Treatment: tetracycline, amoxicillin Helicobacter infection decreases mucus production and causes peptic ulcers. (credit top left photo: modification of work by "Santhosh Thomas"/YouTube; credit top right photo: modification of work by Moriya M, Uehara A, Okumura T, Miyamoto M, and Kohgo Y) Diseases Bacterial: Fungal diseases: Dental caries Thrush Food poisonings Aflatoxin poisoning Cholera Ergot poisoning Gastroenteritis Protozoan diseases: Bacterial Dysentery Amebic dysentery Peptic Ulcers Giardiasis Viral diseases: Cryptosporidiosis Hepatitis A-E Mumps Hepatitis An inflammation of the liver, usually is caused by viruses, but can also be caused by an amoeba and various toxic chemicals Characterized by jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting, and joint pain Types: Hepatitis A, B, C, D, and E Differ in transmission and incubation Hepatitis A Hepatitis A virus: picornavirus Symptoms/Signs 2 week incubation Mostly subclinical Fever, jaundice, headache No chronic disease Transmission: Foodborne Test: IgM antibodies Treatment: Immunoglobulin Vaccine available Hepatitis B Hepatitis B virus: hepadnaviridae 3 distinct particles: Dane particle (infectious and complete) Spherical (half the size) Filamentous (tubular) Spherical and filamentous represent incomplete virions Signs/Symptoms: Mostly subclinical Similar to Hepatitis A without headache More likely to progress to severe liver damage Chronic liver disease may occur About 90% of infants 50% of children 10% of adults 4-26 week incubation Transmission: Bloodborne; Sexual contact; bites Prevention: Vaccine and Universal precautions Treatment: Interferon and nucleoside analogs (antivirals) Hepatitis C Hepatitis C virus: Flaviviridae Symptoms: Similar to Hepatitis A and more likely to become chronic 2-22 week incubation Usually very few symptoms or symptoms go unnoticed. Major cause of liver transplantation in the US Transmission: Parenteral Diagnosis: PCR test Treatment: Peginterferon and ribavirin Protease inhibitors Direct Protein Inhibitors (newest) sofosbuvir and ledipasvir (together can cure some genotypes of virus) No vaccine Extremely infectious Hepatitis D and E Hepatitis D Hepatitis E Hepatitis D virus (deltavirus) Hepatitis E virus (calcivirus) Requires co-infection with B Acquired by ingestion Signs/Symptoms Signs/Symptoms: Severe liver damage Similar to HAV but pregnant women High mortality experience greater mortality Chronic disease more likely Test PCR or IgM 6-26 week incubation Hepatitis A vaccine is protective Parenteral Infection Diganosed via IgM No treatment HBV Vaccine is protective Viral Diseases of the Digestive System Mumps Causative agent: mumps virus (paramyxovirus) Transmission: saliva and droplets entering the oral cavity and respiratory tract After initially replicating in the upper respiratory tract, the virus travels in the blood to the salivary glands and causes them to swell Incubation: 14- 25 days Mumps Signs/Symptoms: parotitis is the most common manifestation Myalgia, weight loss, malaise, headache, and low-grade fever. Symptoms decrease after 1 week and have usually resolve after 10 days. Sterility, deafness, and encephalitis/meningitis can result Prevention: MMR Diseases Bacterial: Fungal diseases: Dental caries Thrush Food poisonings Aflatoxin poisoning Cholera Ergot poisoning Gastroenteritis Protozoan diseases: Bacterial Dysentery Amebic dysentery Peptic Ulcers Giardiasis Viral diseases: Cryptosporidiosis Mumps Hepatitis A-E Ergot and Aflatoxin Poisoning Ergot poisoning Mycotoxins produced by Claviceps purpurea Occurs in grains Restricts blood flow (gangrene) and causes hallucinations Aflatoxin poisoning Mycotoxins produced by Aspergillus flavus Likely to be found on peanuts Causes liver cirrhosis and liver cancer  Ergotism: Claviceps purpurea Transmission: Eating contaminated cereal crops and grasses (rye, wheat, barley, oat, quack grass, wheat and hay) Signs/Symptoms in Animals: Convulsive ergotism includes hyper- excitability, belligerence, ataxia or staggering, lying down, convulsions and backward arching of the back. Signs/Symptoms in humans: Loss of muscle coordination, tremors, and weight loss. Colonial medicine was used to start labor or induce miscarriage By Dominique Jacquin - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7369651 Thrush- Oropharyngeal Candidiasis (OPC) Yeast infection of the mouth and throat caused by Candida albicans Transmission: Fomites, imbalance of oral normal flora Groups: Newborns, children, immunocompromised, particularly persons with AIDS. Signs/Symptoms: White patches in the mouth Inflammation Itching Diagnosis: Swab infected tissue and examine it microscopically Treatment: Oral fluconazole, clotrimazole , or nystatin Diseases Bacterial: Fungal diseases: Dental caries Thrush Food poisonings Aflatoxin poisoning Cholera Ergot poisoning Gastroenteritis Protozoan diseases: Bacterial Dysentery Amebic dysentery Peptic Ulcers Giardiasis Viral diseases: Cryptosporidiosis Mumps Hepatitis A-E Protozoan GI Diseases: Giardiasis Causative agent: Giardia lamblia (G. intestinalis) Flagellated protozoan Transmission: Fecal-oral Contaminated water and food containing cysts of G. lamblia Giardiasis Signs/Symptoms: Bowel inflammation, weight loss, decreased fat absorption resulting in frothy diarrhea, dehydration, deficiencies in fat soluble vitamins, and arthritis (reactive arthritis of Giardia) Explosive bowel movements Diagnosis: Stool sample: Distinctive looks Treatment: Metronidazole (Flagyl) or Quinacrine Prevention: Maintain water supplies free of human or animal wastes Resistant to chlorine, heat and drying Must be filtered out of the water Amoebic Dysentery Causative agent: Entamoeba histolytica Transmission: Fecal-oral Ingesting cysts in food or water contaminated with fecal matter Incubation: 1 to 4 weeks By Ed Uthman from Houston, TX, USA - Amebic colitis (PAS), CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=30103585 Amoebic Dysentery- Sign and Symptoms Mild form: loose stools, stomach pain, and stomach cramping Severe form: Stomach pain, bloody stools, and fever Diagnosis: Stool samples, blood test Treatment: Metronidazole (flagyl) Prevention: Maintenance of sanitary drinking water Boil or filter water Drink bottled water in areas where dysentery is common Cryptosporidiosis Signs and symptoms Severe watery diarrhea with potentially serious complications Pathogen and pathogenesis Caused by Cryptosporidium parvum Pathogenicity of C. parvum is unclear Epidemiology Infection results from drinking contaminated water Diagnosis, treatment, and prevention Presence of oocysts in feces is diagnostic Treated with fluid and electrolyte replacement Prevented with proper hygiene  Immunofluorescent staining allows for visualization of Cryptosporidium spp. (credit: modification of work by EPA/H.D.A. Lindquist)