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Name ___________________________

FST 104 Fall 2008Midterm #1 (Oct 27, 2008)

FOR 1 POINT PLEASE RECORD YOUR NAME, STUDENT ID, AND TEST VERSION LETTER (shownon page 5 of the exam) on a blue Scantron form UCD 2000 using a #2 pencil. Thenrecord the correct answers to questions 1-33. (If you did not bring the Scantron, circlethe letter of the answer directly on the exam pages. Well correct your exam by handfor a 10 point penalty.) [All questions are worth 3 points each]

Multiple guess -- choose the letter of the one correct answer

1. Four of the following diseases are transmitted by eating food containing the agent,but one is a very similar disease that appears to occur spontaneously in a certainpopulation. Which is the spontaneous (or genetic) version of the disease?

A KuruB CJD (Cruetzfeldt-Jacob Disease)C BSE (Bovine Spongiform Encephalopathy)D Feline Spongiform EncephalopathyE vCJD (variant Cruetzfeldt-Jacob Disease which appeared in Great Britain in the 1990s)

2. Which of the following frequently cause illness from contaminated water?A Toxoplasma gondii and Giardia lambliaB Taenia saginata and Toxoplasma gondiiC Cryptosporidium parvum and Diphyllobothrium latumD Giardia lamblia and Cryptosporidium parvumE Giardia lamblia and Taenia saginata

3. What is the mechanism used by Shiga toxin to affect the activity of targeted hostcells?

A Activates adenylate cyclase which catalyzes the synthesis of cAMPB Catalyzes the removal of adenine from the 28S rRNA of the ribosomeC Stimulates actin polymerization leading to intercellular spread of bacteriaD Endonuclease activity causes double strand breaks in host DNAE Stimulates that vagus nerve which cause humans to vomit

4. Which of the following is not true of Campylobacter jejuni?A Closely related to Helicobacter pyloriB The most common cause of bacterial-induced diarrheal illness in United StatesC Illness commonly caused by undercooked chickenD Infection by C. jejuni can trigger Guillain-Barre SyndromeE None of the above

5. Undercooking is the most important factor in the transmission of food-relateddiseases

A Caused by all spore-forming bacteriaB Caused by all Gram negative bacteria

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C Caused by Staphylococcus aureusD Transmitted from animals to humansE Transmitted only from humans to humans

6. What is the typical reason for food-borne illness caused by Staphylococcus aureus?

A Breakdown of water treatment or failure to wash hands before handling foodB Failure to cook the food to a sufficient internal temperature (for example, to 68-71C/155-160F)C Storing the food improperly after touching it with the handsD Existence of a susceptible population the very young, the elderly, and the immunecompromisedE Mixing sheep neural tissue with feed intended for beef cattle

For each of the food-borne disease outbreaks shown, choose the letter of the ONEpathogenic agent listed that would most likely be implicated in each.

7. CASE STUDY I. Many people attending a large multi-generation family picnicexhibited symptoms of vomiting and gastroenteritis within six hours after consuming a lunchconsisting of ice cream, potato salad, and ham sandwiches made with mayonnaise. The potatosalad and sandwiches were prepared early in the morning and kept at ambient temperature(27-30 C; 80-85 F) until mid afternoon. A few of the victims had also drunk water from anearby mountain stream, and some had drunk large amounts of beer. The victims ranged from5 to 76 years of age, and all had fully recovered within two days.

A Giardia lambliaB Listeria monocytogenes

C NorovirusD Staphylococcus aureusE Salmonella enteriditis (or enterica)

8. CASE STUDY II. Four college friends got together for a potluck dinner, which consistedof delicious enchiladas made with chicken cooked to an internal temperature of 54C/130F; freshsalad with commercial ranch dressing; reheated beans; reheated rice; and beer. Between 15 to18 hours after the dinner three of the friends developed gastroenteritis with considerableabdominal discomfort.. The fourth friend was profoundly sympathetic, and he demonstratedthe depth of his sympathy by heartily eating the leftover enchiladas while remarking that hewas certainly glad his appetite was unaffected by illness. He fell ill 16 hours later andmanifested the same symptoms. Assuming that this illness was food-borne, which of the

following agents is the most likely cause?

A Taenia soliumB Salmonella entericaC Shigella dysenteriaeD Campylobacter jejuniiE Clostridium perfringens

9. Which of the following is not true concerning bacteria found in the human gut?

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A There may be 10 times more bacteria in the gut than cells in human bodyB Bacteria found are obligate aerobes, facultative anaerobes or obligate anaerobesC E. coli may constitute less than 0.1% of total gut bacteriaD Many species identified by metagenomics have not yet been cultivatedE Many species identified by metagenomics are novel, i.e. , have not previously been identified

For questions 10 and 11, match each disease listed with ONE likely causative agentchosen from this list: A. Diphylobothrium latum B. Toxoplasma gondii

C. Salmonella typhi D. Hepatitis A virus E. Norovirus

10. Usually asymptomatic but can cause birth defects.11. Gasteroenteritis lasts about one week followed by liver infection, even in healthyyoung adults; jaundice, weakness, and intermittent diarrhea can last for months.

12. Which of the following is a correct match between the pathogen and the beststrategy for its control?

A Clostridium perfringens -- proper cookingB Norovirus -- immunizationC Salmonella enteriditis -- proper storage of food after cookingD Taenia solium -- filtering or boiling drinking waterE Trichinella spiralis -- proper cooking

13. Septicemia refers to infection of what part of the body?A ColonB Central nervous systemC LiverD Blood

E Small intestine

14. What type of cells predominantly cover the surface of the intestinal villi of humans?A MacrophagesB Muscle cellsC EnterocytesD Peripheral nerve cellsE Microvilli

15. Which of the following is true regarding a food borne intoxication?A Ingestion of a very small number of cells is sufficient to cause illnessB The microbe causing the illness must be given the opportunity to proliferate (grow) in the food

C Colonization is an important part of the illnessD Gastroenteritis is the only symptomE Symptoms usually develop more slowly than a food borne infection

16. In the 1970s, which of the following was not thought to be a contributing factor inthe formation of gastric ulcers?

A Stomach acidB Bacterial infectionC Stress

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D Spicy foodsE Pepsin

17. Which of the following is not true about Vibrio parahaemolyticus?A It is associated with seafoodB It causes gastroenteritisC Only strains which are Kanagawa positive cause disease in humansD Some strains produce a thermostable direct hemolysinE Important food pathogen in Japan

18. Which of the following is an incorrect statement regarding Bacillus cereus?A Some strains produce an enterotoxinB Some strains produce an emetic toxinC Steamed rice infected with B. cereus spores, stored at room temperature overnight, andthoroughly reheated can still cause vomitingD It is a common soil bacterium, frequently found in the environmentE None of the above

Know your E. coli. For each type of E. coli described in questions 19-22, pleasechoose the correct letter from the list given immediately below. A letter may be usedmore than once.

A. ETEC B. EIEC C. EPEC D. EAEC E. EHEC

19. Can cause persistent diarrhea lasting 14 days or more.

20. Produces Shiga toxin.

21. Most invasive type.

22. Produces cholera-like toxin.

23. What is the primary cause of food-borne illness caused by spore-forming bacteria?A Mixing offal with feed intended for beef cattleB Contaminated food handlers with poor personal hygieneC Cooking the food properly but storing it improperlyD Failure to cook the food to a sufficient internal temperatureE Improper water sanitation

24. Which of following is not true about food borne viruses that cause human disease?A They can be transmitted from animals to humansB They can be transmitted from human to human

C They are all naked viruses that are engulfed by host-cell phagocytosisD They may cause gastroenteritis and may also damage organs deeper in the bodyE They all contain nucleic acid and protein

25. Quesco Fresco was responsible for a major Listeria monocytogenes outbreak in LosAngeles County. Yet in Mexico, Quesco Fresco has not been associated with L.monocytogenes outbreaks. What is the major reason for this difference?

A Sanitation is better in Mexico

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B Quesco Fresco is more acidic in MexicoC Quesco Fresco has higher salt content in MexicoD Quesco Fresco is not refrigerated in MexicoE B and C

26. Which of the following is not true regarding the agent of mad cow disease?A The non-infectious prion protein is a normal neural protein that many mammals have in theirbodiesB The non-infectious prion protein can spontaneously change into the infectious formC The non-infectious prion protein can become infectious by contact with a foreign infectiousprionD The incubation period of the disease in humans can be many yearsE The infectious prion protein is destroyed by normal cooking

27. Which of the following is a false statement regarding Aspergillus flavus?A It is a fungusB It can cause liver damage following a brief but very high exposure to the disease-causing agent

C It can cause cancer following a low but long term exposure to the disease-causing agentD It causes a food-borne infectionE It causes a food-borne intoxication

28. Before we had a vaccine, paralytic polio was more common among the wealthythan among the less fortunate because:

A Among the wealthy most got polio as infants, and infants are more susceptible to paralysisB Among the less fortunate, most got polio as infants and did not develop paralysis

C The virus first appeared in the United States where poverty was unknownD Wealthy individuals are more likely to be immunocompromisedE The polio virus is carried in foods more common among the wealthy

29. Which of the following is not true for Shigella species?A Only humans carry Shigella species.B All Shigella species are pathogenic.C Most common cause of bacterial dysentery worldwideD Shigella sonnei causes the most severe dysenteryE None of the above

30. Which of the following is a false statement regarding E. coli?

A E. coli O157:H7 (EHEC) can cause kidney damageB Animals (not humans) are the main reservoir for all pathogenic strainsC E. coli O157:H7 (EHEC) can grow (or multiply) in the food if not killed by cooking orpasteurizationD Some E. coli strains are not ordinarily pathogenic for humans

E E. coli (ETEC) can produce an enterotoxin closely related to cholera toxin

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31. Which of the following is an incorrect statement concerning Clostridium botulinumtoxin?

A Its action prevents release of acetylcholine across the synaptic cleftB Its action can result in muscle paralysisC It is taken up into the nerve terminal by exocytosis

D It is a protease that specifically degrades SNARE proteinsE It is not very heat stable

32. Groups of organisms were ranked based on their ability to survive in theenvironment. The groups are listed in alphabetical order below. If ordered mostresistant (survive best) to least resistant, what group of organisms would rank third?

A bacterial endosporesB enveloped virusesC Gram-negative vegetative cellsD Gram-positive vegetative cellsE naked viruses

33. Luncheon or deli meats are relatively neutral in pH, have a high salt content,arestored in the refrigerator (< 7C/45F), and are seldom re-heated before eating. From amicrobiological point of view, this composition and storage condition make such meatsa medium that selects for the growth of which of the following?

A E. coli O157:H7 (EHEC)B Listeria monocytogenesC Clostridium perfringensD Staphylococcus aureusE Trichinella spiralis