1 Show 1) The most frequently used portal of entry for pathogens is the
2 2) The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host's antibodies is called
3 3) Most pathogens that gain access through the skin
4 4) The ID50 is
5 5) All of the following contribute to a pathogen's invasiveness EXCEPT
E) coagulases 6 6) Which of the following statements is FALSE?
7 7) Which of the following statements about exotoxins is generally FALSE?
8 8) Endotoxins are
9 9) Which of the following is NOT a membrane-disrupting toxin?
10 10) Cytopathic effects are changes in host cells due to
11 11) Which of the following does NOT contribute to the symptoms of a fungal disease?
12 12) All of the following are methods of avoiding host antibodies EXCEPT
13 13) Siderophores are bacterial proteins that compete with the host's
14 14) The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of
15 15) All of the following are examples of entry via the parenteral route EXCEPT
16 16) Superantigens produce intense immune responses by stimulating lymphocytes to produce
17 17) Botulism is caused by ingestion of a proteinaceous exotoxin; therefore, it can easily be prevented by
18 18) All of the following organisms produce exotoxins EXCEPT
19 19) Which of the following cytopathic effects is cytocidal?
20 20) All of the following are used by bacteria to attach to host cells EXCEPT
21 21) Symptoms of protozoan and helminthic diseases are due to A) tissue damage due to growth of the parasite on the tissues. B) waste products excreted by the parasite. C) products released from damaged tissues. D) tissue damage due to growth of the parasite on the tissues and waste products excreted by the parasite. E) tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissues. 22 22) Which of the following statements about staphylococcal enterotoxin is FALSE?
23 23) Which of the following contributes to the virulence of a pathogen?
24 24) Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages
25
25) Twenty-five people developed symptoms of nausea, vomiting, and diarrhea three to six hours after attending a church picnic where they ate a ham and green bean casserole with cream sauce. The most likely cause of this case of food intoxication is
26 26) Which of the following statements about M protein is FALSE?
27 27) Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to
28 28) Which of the following is an example of direct damage due to bacterial infection?
29 29) Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?
30 30) All of the following bacteria release endotoxin EXCEPT
31 31) Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed,
32 32) Bacteria such as E. coli and Salmonella produce invasins that bind host cells, thus causing the cells to
33 33) Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier?
34 34) Injectable drugs are tested for endotoxins by
Answer: A 35 35) Endotoxins in sterile injectable drugs could cause
36 36) Gram-negative septic shock results from the following events. What is the second step?
37 37) Antibiotics can lead to septic shock if used to treat
38 38) Which of the following is NOT a cytopathic effect of viruses?
39 Table 15.1 shows the ID50 for Staphylococcus aureus in wounds with and without the administration of ampicillin before surgery. Based on the data, the administration of ampicillin before surgery
40 40) Which organism in Table 15.2 most easily causes an infection?
41 41) Which organism in Table 15.2 causes the most severe disease?
42 42) Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that
43 43) Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by
44 44) In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes
45 45) Patients developed inflammation a few hours following eye surgery. Instruments and solutions were sterile, and the Limulus assay was positive. The patients' inflammation was due to
46 1) In general, the LD50 for exotoxins is much greater than the LD50 for endotoxins. 47 2) Biofilms provide pathogens with an adhesion mechanism and aid in resistance to antimicrobial agents. 48 3) The M protein enhances the virulence of Streptococcus by preventing phagocytosis. 49 4) In A-B exotoxins, the A component binds to the host cell receptor so that the B component can enter the cell. 50 5) The Limulus amoebocyte assay is used to detect minute amounts of endotoxin in drugs and medical devices. 51 6) Cytopathic effects, such as inclusion bodies and syncytium formation, are the visible signs of viral infections. 52 7) Ergot and aflatoxin are toxins sometimes found in grains contaminated with fungi. 53 8) Most symptoms of endotoxins can be treated with administration of anti-endotoxin antibodies. 54 9) Infections with some viruses may induce chromosomal changes that alter the growth properties of host cells. 55 10) Many pathogens use the same portal for entry and exit from the body. Which is a method of avoiding phagocytosis?One obvious strategy in defense against phagocytosis is direct attack by the bacteria upon the professional phagocytes. Any of the substances that pathogens produce that cause damage to phagocytes have been referred to as aggressins. Most of these are actually extracellular enzymes or toxins that kill phagocytes.
Which of the following are used by bacteria to attach to host cells?Cell wall adhesins are surface proteins found in the cell wall of various bacteria that bind tightly to specific receptor molecules on the surface of host cells. Bacteria can typically make a variety of different cell wall adhesins enabling them to attach to different host cell receptors.
Which of the following is the most frequently used portal of entry for pathogens in humans?The respiratory tract is the most frequently used portal of entry. Pathogens are able to enter the mouth and nose by air, via dust particles, moisture, and respiratory droplets from an infected person.
What are Leukocidins?A leukocidin is a type of cytotoxin created by some types of bacteria (Staphylococcus). It is a type of pore-forming toxin. The model for pore formation is step-wise. First, the cytotoxin's āSā subunit recognizes specific protein-containing receptors, or an integrin on the host cell's surface.
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