Microbial Diseases of the Digestive System PDF

MICROBIAL DISEASES OF THE DIGESTIVE SYSTEM FARHANAH AHMAD SHUHAIMI CENTRE FOR DIETETICS STUDIES FACULTY OF HEALTH SCIENCES UNIVERSITI TEKNOLOGI MARA NORMAL MICROBIAL FLORA OF THE DIGESTIVE SYSTEM Mouth – 1 ml saliva = millions of bacteria Stomach and small intestine – Few organ...

MICROBIAL DISEASES OF THE DIGESTIVE SYSTEM FARHANAH AHMAD SHUHAIMI CENTRE FOR DIETETICS STUDIES FACULTY OF HEALTH SCIENCES UNIVERSITI TEKNOLOGI MARA NORMAL MICROBIAL FLORA OF THE DIGESTIVE SYSTEM Mouth – 1 ml saliva = millions of bacteria Stomach and small intestine – Few organisms due to HCl and rapid movement of food Large intestine – 100 billion bacteria per gram of feces – 40 % of fecal mass is microbial cell material Lactobacillus, Bacteriodes, Enterobacter, E. coli. Proteus spp. BACTERIAL DISEASES OF LOWER G.I. Infections Intoxications – Pathogens enters G.I. Tract – Ingestion of a preformed and multiples toxin – Bacteria may penetrate the – Sudden onset of symptoms intestinal mucosa or may ( few hours ) pass to other systemic – Fever not always present organs – Delay in appearance of symptoms while pathogen increases in number or invades tissue – Usually a fever  BACTERIAL DISEASES OF LOWER G.I. Diarrhea – infections and intoxications – Blood or mucus - dysentery Abdominal cramps, nausea and vomiting – Defense mechanism to rid body of harmful material Gastroenteritis – Inflammation of stomach or intestinal mucosa CAMPYLOBACTER GASTROENTERITIS Campylobacter jejuni – Gram (-), microaerophilic spiral – Found in the intestines of many animals, especially poultry – Commonly associated with poultry, and is also often found in animal feces. – This species of microbe is one of the most common causes of food poisoning in Europe and in the US, with the vast majority of cases occurring as isolated events rather than mass outbreaks. ESCHERICHIA GASTROENTERITIS 1. ETEC - enterotoxigenic E. coli – Not invasive – Enterotoxin – watery diarrhea 2. EIEC - enteroinvasive E. coli – Invades intestinal wall – Inflammation, fever & Shigella-like dysentery 3. EHEC - enterhemorrhagic E. coli – E. coli O157: H7 – Found in intestines of animals, especially cattle – Hemorrhagic colitis – inflammation of colon with bleeding – HUS – Hemolytic Uremic Syndrome Blood in urine leading to kidney failure (kidneys effected by toxin) SHIGELLOSIS (BACILLARY DYSENTERY) Bacterial infection - Shigella sp. Gram (-), facultative, rods – Shigella sonnei – Shigella dysenteriae – Shigella flexneri – Shigella boydii Incubation period: – 12 hours to 2 weeks Usually fever – Mild case of Shigellosis The most common symptoms of shigellosis : – mucoid bloody diarrhea – fever – abdominal pain – Tenesmus  TOXIN Shiga toxin – Kiyoshi Shiga – Japanese physician and bacteriologist. – Shiga was credited with the discovery and identification of the Shigella dysenteriae microorganism which causes dysentery, and the Shiga toxin which is produced by the bacteria. Extremely virulent Bacteria invade intestinal mucosa – produce toxin Severe diarrhea with blood in stool (dysentery) Toxin inhibits Protein Synthesis – Cells lining G.I. tract are shed – Up to 20 bowels movements a day 20,000 – 30,000 cases per year in U.S. 5 – 15 deaths Shigella dysenteriae – more severe  SALMONELLOSIS (SALMONELLA GASTROENTERITIS) Bacterial Infection – Salmonella sp. Salmonella – Gram (-), facultative, non-spore forming rods – Found in G.I. Tract of humans and many animals – All are considered pathogenic – Salmonella infection is usually caused by eating raw or undercooked meat, poultry, and eggs or egg products or by drinking unpasteurized milk. SALMONELLOSIS Incubation time 12 – 36 hours Bacteria invade the intestinal mucosa and multiply May pass thru mucosa into lymphatic or circulatory system and become systemic Fever, abdominal pain, cramps and diarrhea  SALMONELLOSIS 1 billion Salmonella per gram of feces Mortality rate < 1 % – Higher in infants and elderly Recovery in a few days – Some may shed bacteria in feces for 6 months  SALMONELLOSIS Contamination – Meats, poultry, eggs, pet reptiles (turtles) Undercooked or raw eggs – Cookie batter – Salads – “Sunny side up” fried eggs  TYPHOID FEVER Salmonella typhi - most virulent Salmonella Only found in humans (feces) Systemic disease – Spreads thru body, found in blood, urine, feces Mortality rate 1-2 %, used to be 10 % – Was common before days of proper sewage treatment – Still common in Third World countries  TYPHOID MARY Mary Mallon aka Thyphoid Mary – cook in N.Y. Asymptomatic carrier of pathogen bacterium Salmonella typhi – Responsible for several outbreaks and many deaths – Refused to leave her job 1 – 3 % become chronic carriers – Microbe lives in gallbladder and is shed in feces  CHOLERA Vibrio cholerae - Gram (-) curved rod Endemic in Asia and India Cholera toxin – Secretion of Cl- leads to H2O loss and diarrhea – 12 – 20 liters of fluid per day FOOD POISONING FROM SEAFOOD Vibrio parahaemolytica – Found in salt H2O – Associated with poisoning from Raw oysters Shell fish Shrimp crabs STAPHYLOCOCCAL FOOD POISONING (STAPHYLOCOCCAL INTOXICATION) Ingesting an enterotoxin by Staph. aureus Staphylococci – High resistance to heat – Resistant to drying out – Resistant to high osmotic pressures – Resistant to high salt concentration – Found in nasal passages and hands Contaminate food * 1 million bacteria per gram of food to produce enough enterotoxin to cause illness MOST RELIABLE METHOD OF PREVENTING STAPHYLOCOCCAL INTOXICATION: After food is cooked, do not keep it at room temperature if it will not be served and eaten soon → Instead, keep it heated to 60°c or hotter or refrigerate it at 4°c or colder. Perishable food that has been in the "danger zone" should be refrigerated within 2 hours (or 1 hour if the food has been at 32°c or hotter, such as in a car or at a picnic). Toxin – Triggers vomiting reflex center of brain – Abdominal cramps & diarrhea – Recovery is usually complete in 24 hours. – Mortality rate – 0 % in healthy people  PEPTIC ULCERS Peptic ulcers are open sores on the inner lining of the stomach and the upper part of the small intestine. The most common symptom →stomach pain. Peptic ulcers include: – Gastric ulcers – Duodenal ulcers Common cause – Helicobacter pylori – microaerophilic spiral 30% - 50 % of normal population are infected, but only 15% of those develop ulcers How is H. pylori infection diagnosed? – A breath test: In this test, you exhale into a bag before and after drinking a solution. The test measures the amount of carbon dioxide released in your breath before and after drinking the solution. A higher level after drinking the solution means H. pylori are present. – A stool test: This test looks for evidence of H. pylori in a stool sample. – Upper endoscopy: A flexible tube is inserted down the throat into the stomach. A small tissue sample from the stomach or intestine lining is taken for testing for the presence of H. pylori. VIRUSES HEPATITIS Inflammation of the liver Viral Hepatitis 5 different viruses – Hepatitis A – Hepatitis B – Hepatitis C – Hepatitis D – Hepatitis E HEPATITIS A (INFECTIOUS HEPATITIS) HAV - ssRNA no envelope – Enters via oral route, multiplies in G.I. Tract spreads to liver – Virus is shed in feces – HAV is resistant to normal chlorine disinfectants used for water – HAV can survive several days on surfaces (cutting boards) 50% of infections are subclinical – Symptoms Nausea, diarrhoea, abdominal discomfort, fever, jaundice Recovery results in lifelong Immunity – No chronic Hepatitis A  HEPATITIS B (SERUM HEPATITIS) HBV - ds DNA envelope Transmitted by blood, semen, saliva, breast milk 50% cases asymptomatic – Symptoms Loss of appetite fever, joint pains, jaundice 10% become chronic carriers of HBV – Chronic carriers are 200 times more likely to develop liver cancer THANK YOU