The most frequently used portal of entry for pathogens is the
c. mucous membranes of the gastrointestinal tract.
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
e. antigenic variation.
Most pathogens that gain access through the skin
a. enter through hair follicles and sweat ducts.
The ID50 is
c. the dose that will cause an infection in 50 percent of the test population.
All of the following contribute to a pathogen's invasiveness EXCEPT
d. toxins.
Which of the following statements is FALSE?
a.Coagulase destroys blood clots.
Which of the following statements about exotoxins is generally FALSE?
e.They are resistant to heat.
Endotoxins are
d.part of the gram-negative cell wall.
Which of the following is NOT a membrane-disrupting toxin?
a.A-B toxin
Cytopathic effects are changes in host cells due to
d.viral infections.
Which disease-associated fungi or fungal characteristics are mismatched?
d.Claviceps purpura - aflatoxin
All of the following are methods of avoiding host antibodies EXCEPT
a.membrane-disrupting toxins.
Siderophores are bacterial proteins that compete with the host's
b.iron-transport proteins.
The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of
a.adhesins and ligands.
All of the following are examples of entry via the parenteral route EXCEPT
a.hair follicle.
Superantigens produce intense immune responses by stimulating lymphocytes to produce
b.cytokines.
Botulism is caused by ingestion of a proteinaceous exotoxin; therefore, it can easily be prevented by
e.boiling food prior to consumption.
All of the following organisms produce exotoxins EXCEPT
e.Salmonella typhi.
Which of the following cytopathic effects is cytocidal?
c.release of enzymes from lysosomes
All of the following are used by bacteria to attach to host cells EXCEPT
e.A-B toxins.
Symptoms of protozoan and helminthic diseases are due to
b.tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissues.
Which of the following statements about staphylococcal enterotoxin is FALSE?
c.It is produced by Staphylococcus aureus growing in the host's intestines.
Which of the following contributes to the virulence of a pathogen?
c.numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production
Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages
a.give new gene sequences to the host bacteria.
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
c.staphylococcal enterotoxin.
Which of the following statements about M protein is FALSE?
a.It is readily digested by phagocytes.
Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to
b.superantigens.
Which of the following is an example of direct damage due to bacterial infection?
c.the invasion and lysis of intestinal cells by E. coli
Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?
d.mucous membranes only
All of the following bacteria release endotoxin EXCEPT
b.Clostridium botulinum.
Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed,
b.polypeptide B would not be able to enter the cells.
Bacteria such as E. coli and Salmonella produce invasins that bind host cells, thus causing the cells to
d.engulf the bacteria.
Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier?
a.inducing TNF
Injectable drugs are tested for endotoxins by
d.the Limulus amoebocyte lysate test.
Endotoxins in sterile injectable drugs could cause
c.septic shock symptoms.
Gram-negative septic shock results from the following events. What is the second step?
a.LPS is released from gram-negative bacteria.
Antibiotics can lead to septic shock if used to treat
a.gram-negative bacterial infections.
Which of the following is NOT a cytopathic effect of viruses?
b.toxin production
Table 15.1
Bacterium Portal of Entry ID50
Staphylococcus aureus Wound
<10
Staphylococcus aureus Wound + Ampicillin 300
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
a.decreases the risk of staphylococcal infection.
b.replaces
tetracycline.
c.increases the risk of staphylococcal infection.
d.has no effect on risk of infection.
e.The answer cannot
be determined based on the information provided.
a.decreases the risk of staphylococcal infection.
Table 15.2
Bacterium ID50
E. coli O157:H7 20
Legionella pneumophila
1
Shigella 10
Treponema pallidum 57
Which organism in Table 15.2 most easily causes an infection?
a.E. coli O157:H7
b.Shigella
c.Treponema
pallidum
d.Legionella pneumophila
e.The answer cannot be
determined based on the information provided.
d.Legionella pneumophila
Table 15.2
Bacterium ID50
E. coli O157:H7 20
Legionella pneumophila
1
Shigella 10
Treponema pallidum 57
Which organism in Table 15.2 causes the most severe disease?
a.E. coli O157:H7
b.Shigella
c.Treponema
pallidum
d.Legionella pneumophila
e.It cannot be determined
from the information provided.
e.It cannot be determined from the information provided.
Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that
b.streptococcal colonization is necessary for periodontal disease.
Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by
e.lysogenic conversion.
In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes
b.a decrease in blood pressure.
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
c.endotoxin.
The best description of direct damage by a pathogen is
d.host cells destroyed when pathogens metabolize and multiply
Which is NOT specifically employed by pathogens to avoid destruction by phagocytosis?
c.producing superantigens
A retired contract administrator who enjoyed gardening sought medical attention for what appeared to be a sinus infection. He received antimicrobials but the conditioned worsened and he was experiencing severe painful spasms in his jaw. He admitted to injuring himself with a gardening tool while wearing sandals in the yard but did not seek medical attention for the wound. The man is likely experiencing
a.intoxication caused by a focal C. tetani infection.
b.allergic rhinitis.
For what reason might the ID50 for Salmonella Typhi decrease when a rat simultaneously ingests sulfa drugs with the pathogen?
c.The antimicrobial interferes with the microbiome enabling the pathogen to more easily establish infection.
Which pathogen and virulence factor are mismatched?
b.Shigella sonnei - coagulase