Chapter
12
1. Seventeen patients in ten hospitals
had cutaneous infections caused by Rhizopus. In all seventeen patients,
Elastoplast bandages were placed over sterile gauze pads to cover wounds.
Fourteen of the patients had surgical wounds, two had venous line insertion
sites, and one had a bite wound. Lesions present when the bandages were removed
ranged from vesiculopustular eruptions to ulcerations and skin necrosis
requiring debridement. Fungi are more likely than bacteria to contaminate
bandages because they
Can tolerate low-moisture conditions
2. In mid-December, a woman with
insulin-dependent diabetes who had been on prednisone fell and received an
abrasion on the dorsal side of her right hand. She was placed on penicillin. By
the end of January, the ulcer had not healed, and she was referred to a plastic
surgeon. On January 30, a swab of the wound was cultured at 35°C on blood agar.
On the same day, a smear was made for Gram staining. The Gram stain showed
large (10 µm) cells. Brownish, waxy colonies grew on the blood agar. Slide
cultures set up on February 1 and incubated at 25°C showed septate hyphae and
single conidia. The most likely cause of the infection is a
Dimorphic fungus
3. Ringworm is caused by a(n)
Fungus
4. A definitive host harbors which stage
of a parasite?
Adult
5. The life cycle of the fish tapeworm
is similar to that of the beef tapeworm. Which of the following is the most
effective preventive measure?
Cooking fish before eating
Chapter
12 – Reading Questions
1. The term dermatophyte is
typically used for fungi that cause which of the following?
Cutaneous mycoses
Chapter
13
1. Which of the following statements
about viruses is FALSE?
Viruses use their own catabolic enzymes
**TRUE: viruses have genes; viruses
contain DNA or RNA but never both; viruses contain a protein coat; viruses use
the anabolic machinery of the cell
2. Dogs do not get measles because their
cells lack the correct receptor sites for that virus.
TRUE
3. A clear area against a confluent
"lawn" of bacteria is called a
Plaque
4. The definition of lysogeny is
Phage DNA is incorporated into host cell
DNA
5. An envelope is acquired during which
of the following steps?
Release
6. Most drugs that interfere with viral
multiplication also interfere with host cell function.
TRUE
Microbiology
Animation: Prions: Characteristics
1. The normal function of the PrP protein
in mammals is believed to be:
assisting in normal synaptic development
and function.
2. How do normal prion proteins (PrP)
differ from the infectious prion proteins?
Normal PrP have alpha-helices;
infectious PrP have beta-pleated sheets.
3. How does the number of infectious
prions increase?
Prions transform normal proteins into
the misfolded beta-pleated sheet configuration; therefore, prions multiply by
conversion.
4. Why are the beta-pleated multimers of
PrP potentially pathogenic?
The multimers are more stable and
resistant to protease.
Chapter
12 – Reading Questions
1. Dinoflagellates are a type of
unicellular __________. One genus of dinoflagellates is responsible for a
foodborne disease called __________.
algae; paralytic shellfish poisoning
(PSP)
**Dinoflagellates are a type of
unicellular algae. During red tide, high levels of a neurotoxin produced by Alexandrium
(a dinoflagellate) are found in shellfish. Consumption of these shellfish leads
to a foodborne disease called paralytic shellfish poisoning.
Chapter
12
1. Which of the following arthropods
does NOT transmit diseases by sucking blood from a human host?
Houseflies
2. Helminthic diseases are usually
transmitted to humans by
Gastrointestinal route
3. The sporozoite, merozoite,
gametocyte, and ring stages are all part of the Plasmodium life cycle
TRUE
4. Which of the following is the most
effective control for malaria?
Eliminate Anopheles
5. Which of the following tends to be
more complex in a parasitic helminth than in free-living helminths?
Reproductive system
What
Does Old Age have to Do with it?
Barbara, a 68-year-old retired
schoolteacher, was beside herself. Her husband Bob had passed away only a month
ago, and a week later, her youngest daughter, 40-year-old Maria, had moved back
in with her. Maria was in the process of divorcing her husband and was seeking
sole custody of her three children. The children, ages 6, 8, and 12, were also
living in the house with their grandmother. Barbara enjoyed playing games, gardening,
and taking walks with her family, and on the whole did not mind having the
extra company. The extra cooking and cleaning were taking a toll on her health,
however. One morning, Barbara woke up with excruciating pain on her right rib
cage. When she looked at her side in the bathroom mirror, she found that she
had an extremely red rash with little vesicular lesions. The rash was localized
to her right side and looked very similar to Image A. Concerned about the rash
and the amount of pain associated with it, Barbara phoned her physician’s
office and made an appointment for that afternoon.
During her appointment, Barbara
discusses her current and previous medical history with Dr. Jones. Up until
this rash appeared, Barbara had been a healthy individual. She is the
appropriate weight for her height, and her blood counts have always been within
normal ranges. As an adult, she rarely has gotten sick, even with minor
illnesses such as colds. As a child, Barbara had received all of the
appropriate vaccinations as scheduled and had been a relatively healthy young
lady. In fact, Barbara could remember missing school for illnesses only twice
during her entire school career: once when she had chickenpox in second grade,
and once in high school when she had a severe case of the flu. Barbara’s
medical history confirms Dr. Jones’s suspicion of a latent infection, so there
is no need for sample collection.
After asking a few more questions about
her medical history, Dr. Jones asks Barbara about her current living situation.
Barbara mentions that her grandchildren are living with her. Dr. Jones asks
about their general health. Barbara responds that the 6-year-old is getting
over a cold, but that overall they are healthy individuals. Dr. Jones gives
Barbara a prescription for acyclovir and tells her to come back if she has any
further complications.
1. Which of the following best describes
Barbara’s condition?
Shingles caused by the herpes zoster
virus
**As a child, Barbara was infected with
the varicella virus and contracted chickenpox. Though she recovered from the
chickenpox, the virus was able to enter the peripheral nerves and eventually
the central nerve ganglion, where it persists as viral DNA hidden from her
immune response. As a result of factors in her life, Barbara’s virus was
reactivated and traveled along the peripheral nerves to the cutaneous sensory
nerves of the skin. This new outbreak produces the rash characteristic of a
shingles infection. The occurrence of shingles is 10% to 20% in individuals who
have had chickenpox.
2. What is the correct sequence of
events for the replication of a DNA virus?
a.
virions attach to the host cells
b.
viral DNA is released into the nucleus of the host cell
c.
enzymes required for multiplication of viral DNA are produced via transcription
and translation
d.
a copy of the DNA is made
e.
capsid and other structural proteins are manufactured
f.
virions ae assembled to form complete viruses and are released from the host
cell
3. Which of the following factors could
have contributed to Barbara’s development of shingles?
Her daughter and grandchildren moving
into her house shortly after the death of her husband
Her age, 68.
**Many factors can contribute to reactivation
of a latent virus. Research has yet to narrow it down to one thing, but stress,
old age, and a change in the host’s immune system have been linked to viral
reactivation.
4. Barbara is worried about spending
time with her grandchildren while being treated for shingles. Can her
grandchildren contract chickenpox or shingles from spending time with their
grandmother?
No. Because of their ages, the
grandchildren have most likely been vaccinated against the chickenpox. They are
also safe from contracting shingles because they are young.
What disease does the human
herpesvirus-1 cause?
Cold sores or fever blisters
No comments:
Post a Comment