Bio 274 1st Edition Final Exam Study Guide Final Exam Study Guide Chapters 25 24 26 22 23 21 Chapter 25 second half of this chapter Microbial Diseases of the Digestive System Campylobacter Gastroenteritis gram negative microaerophilic spirally curved bacteria o Leading cause of foodborne illness o Adapt well to intestinal environment of animal hosts especially poultry o Like low O2 high CO2 optimum growth at 42 C o 2 million cases of Campylobacter gastroenteritis in US annually usually caused by C jejuni o Characterized by fever cramping ABD pain diarrhea or dysentery o Recovery occurs in 1 week o Unusual complication 1 in 1000 cases is neurological disease Guillain Barr syndrome a temporary paralysis Surface molecule of bacteria resembles a lipid component of nervous tissue provokes autoimmune attack Helicobacter Peptic Ulcer Disease spiral shaped microaerophilic bacterium o Causes most cases of peptic ulcer disease o 30 50 of population become infected Only 15 of infected hosts develop ulcers Certain host factors are involved people with Type O blood are more susceptible o Stomach produces gastric juices that help digest food a specialized layer of mucus that protects the stomach itself from digestion If this defense is disrupted stomach inflammation gastritis results Which progresses to ulcerated area H pylori can live in highly acidic environment o Treated with antibiotics o Tested with biopsy of tissue culture of organism Yersinia gastroenteritis gram negative bacteria that includes Yersinia enterocolitica and Y pseudotuberculosis o Intestinal inhabitancts of many domestic animals o Transmitted via milk or meat o Able to grow at refridgerator temps 4 C o Yersinia can be cause of severe reactions when it contaminates blood transfusions o Symptoms diarrhea fever headache severe ABD pain o Recovery takes 1 2 weeks Clostridium perfringens gastroenteritis 1 of more common forms of food poisoning in US o Large gram positive endospore forming obligately anaerobic rod bacterium o Transmitted via meat meat stews contaminated w guts during slaughter o Heating allows its growth o Produces exotoxin that causes ABD pain diarrhea o Most cases are mild often undiagnosed recovery 8 12 hours after ingestion Clostridium difficile Associated Diarrhea causes more deaths than all other intestinal infections combined o Gram positive endospore forming anaerobe found in poo o Produces exotoxins that cause disease symptoms from mild diarrhea to life threatening colitis Colitis can result in ulceration or perforation of intestinal walls o Results in extended use of antibiotics especially fluoroquinolones o Occurs mostly as nosocomial infections in hospitals nursing homes o Mortality rate is highest in elderly o Test with immunoassay that detects responsible exotoxins cytoxin assay is more reliable but takes 2 days to complete o Treatment discontinue antibiotics prescribe metronidazole if that doesn t work prescribe rifaximin or nitazoxanide o In exceptional cases enemas containing HUMAN POO are used to restore normal microbiota this is very successful but very unpopular Bacillus cereus Gastroenteritis large gram positive endospore forming bacterium o Common in soil vegetation o Normally harmless o Cause of outbreaks of foodborne illness o Hot food that is cooling allows microbes to germinate Common in rice dishes in Asian restaurants o Diarrhea sometimes nausea vomiting Viral Diseases of Digestive System Mumps inflammation swelling of the parotid glands 1 of 3 pars of salivary glands located just below in front of ears fever pain during swallowing caused by virus o Symptoms appear 16 18 days after exposure o Virus transmitted via saliva respiratory secretions o Testes can become enlarged orchitis 4 7 days after onset of symptoms o Vaccine available MMR o Diagnosed bases on symptoms can be isolated tested with ELISA test Hepatitis inflammation of liver caused by at least 5 different viruses o Hepatitis A hepatitis A virus HAV is causative agent of hepatitis A Virus contains single stranded RNA that lacks envelope Enters via oral route multiplies in epithelial lining of GI tract Viremia virus in blood occurs virus spreads to liver kidneys spleen Virus shed in feces Symptoms anorexia nausea diarrhea ABD discomfort fever chills More likely in adults last 2 21 days Morality rate is low Diagnosed by detection of IgM anti HAV antibodies Recovery lifelong immunity No specific treatment o Hepatitis B hepatitis B virus HBV larger than HAV Double stranded DNA that s enveloped o o Unique because it replicated its DNA directly by passing thru RNA stage Often transmitted via blood transfusions Contains 3 distinct particles 1 Complete virion largest infectious capable of replicating o aka Dane particle 2 Spherical particle half the size of Dane particle 3 Filamentous particle tubular particles similar in diameter to spherical particle but 10x longer o Spherical particles filamentous particles are both unassembled components of virion w o nucleic acids Assembly is inefficient so there are many of these particles o These particles contain hepatitis B surface antigen HBsAg which can be detected in a diagnostic test for antibodies Transmitted via shared needles accidental needle sticks semen saliva breast milk but NOT in urine feces Those at a higher risk Health care workers homosexuals heterosexuals w many partners Asians Africans Acute Hepatitis B most cases resolve spontaneously as patient clears virus Infected person is often unaware In about 1 3 of the cases the infected person develops symptoms o Low grade fever nausea ABD pain Chronic Hepatitis B if a case of Hepatitis A persists for 6 months the condition is considered chronic People infected from very young are most likely to become chronic carriers o Risk for infants is 90 children 1 5 years 25 50 adolescents 6 10 Sometimes condition is asymptomatic others suffer from malaise loss of appetite general fatigue o If chronic infection results in liver cirrhosis patient becomes seriously ill Diagnosis of HBV is based on symptoms then tests of liver function No specific treatment for acute HBV 7 treatments for chronic HBV Hepatitis C HCV single strand RNA enveloped doesn t kill infected cell triggers an immune inflammation response that either clears infection or slowly destroys liver silent epidemic Kills more people than AIDS in the US Cannot be detected until 70 80 days after infection No recognizable symptoms until 20 years after infection Over 1 3 of