Mod 5 Test

Question 1

The concept of treating all samples, whether known or unknown, as potentially hazardous (or pathogenic) materials is known as __________.

Answer 1

Universal precautions

Question 2

List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample.

Answer 2

A lab researcher would be certain to note:

Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above

Question 3

While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would you determine first and why?

Answer 3

You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the organism, making any observations regarding motility impossible. The correct approach would be to place the liquid culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram stained.

Question 4

A facultative anaerobe is a microorganism capable of growth under what conditions?

Answer 4

A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions.

Question 5

As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why?

Answer 5

Streptococcus would not survive in the presence of peroxides—it is unable to breakdown peroxides (catalase negative). Left unchecked, peroxides would damage the cellular integrity of Strep causing lysis/cell death.

Question 6

Streptococcus is most often streaked onto:

Answer 6

Blood agar
Strep is often cultured on Blood agar plates to determine its hemolytic properties, which aids in the classification (and differentiation) process.

Question 7

True or False. The Lancefield groups are used to subdivide antigenic groups of gamma-hemolytic Streptococcus.

Answer 7

False
The Lancefield groupings are used to subdivide beta-hemolytic Strep.

Question 8

Greater than 90% of all human streptococcal infections belong to:

Answer 8

Group A
Group A is the causative agent behind > 90% of all Strep infections.

Question 9

Rheumatic fever displays ______ hemolytic activity and occurs when _______ is left untreated.

Answer 9

Beta; Strep. Pharyngitis
Strep throat (also known as strep. Pharyngitis) can lead to Rheumatic fever if left untreated and displays beta-hemolytic activity.

Question 10

True or False. Under most circumstances, staphylococcus can be found in ~80% of human population where it remains non-symptomatic.

Answer 10

False

Question 11

When a bacterium neither harms nor benefits from the host from which it obtains nutrients, it is referred to as being ___________.

Answer 11

Commensal

Question 12

Match the step of infection to its description.

Invasion
Evasion
Transmission

Question 13

Match the following diseases with their respective symptoms:

1. folliculitis A. Childhood skin disease near
   mouth/nose
2. scalded-skin syndrome B. Infection of thin, transparent
   scleral tissue
3. impetigo C. Infection occurs at time of birth
4. conjunctivitis D. Pus-filled lesions on skin or hair
5. ophthalmia neonatorum E. Ruptured pustules; treated with
   penicillin

Answer 13

1D
2E
3A
4B
5C

Question 14

True or False. Staphylococcus is the only causative agent of conjunctivitis.

Answer 14

False
There are bacterial (staph) and viral forms of conjunctivitis, both resulting in the inflammation of the conjunctiva and ‘pink eye.’

Question 15

True or False. An acid-fast stain is best suited to identify tuberculosis (as opposed to a Gram stain).

Answer 15

True
TB shows a poor Gram stain and should be screened via an acid-fast stain.

Question 16

True or False. When located outside of the lung, TB is usually non-infectious.

Answer 16

True
Although TB can move systemically through the blood and infiltrate other areas (brain, spine and kidney), when located outside of the lung, TB tends to be non-infectious.

Question 17

Identify the disease based on the following (select all that apply):

It is a small, acid-fast rod usually remaining asymptomatic for up to 20 years. It affects the skin, nerves, upper respiratory tract, and eyes of infected individuals.

Tuberculosis
Bacterial conjunctivitis
Hansen’s disease
Leprosy
Scalded-skin syndrome

Answer 17

Hansen’s disease
Leprosy
B and D. Hansen’s disease is simply another name for Leprosy. Leprosy is characterized by its ability to remain dormant for up to 20 years as well as the effects observed relative to the patients skin, nerves, lungs and eyes.

Question 18

True or False. Directly ingesting clostridium or its associated spores will not cause illness in adults.

Answer 18

True

Question 19

A 5-month-old child is given honey at breakfast and begins showing symptoms consistent with botulism. Would the child’s illness be classified as foodborne, infant, or wound botulism?

Explain why it would NOT be classified as the other two options.

Answer 19

Infant. Although food (honey) is consumed, foodborne botulism is derived from improperly canned, low acid foods under anaerobic conditions. Such conditions were not described. No puncture wounds or injuries were described, ruling out wound. The child is suffering from infant botulism, as honey is a potential carrier of clostridium. The intestinal track of young children is still developing and clostridium is able to colonize and produce the associated toxin.

Question 20

True or False. Although there is no cure for tetanus, it can be prevented through vaccination.

Answer 20

True
There is no cure for tetanus. However, tetanus is entirely preventable through vaccination.

Question 21

Identify the medical condition characterized by robust carbohydrate fermentation, swelling of the infected areas, and fever. Explain why hyperbaric oxygen therapy is a possible treatment.

Answer 21

Gas gangrene, because C. perfringens is an anaerobic bacteria

Question 22

Why does the alpha toxin (perfringolysin) produced during an infection of gas gangrene cause cell death?

Answer 22

The toxin perforates the membrane. It forms pores in the plasma membrane of host cells resulting in uncontrolled ion fluxes and eventually cell lysis and death.

Question 23

You develop a fever, chills, and pneumonia after recently returning from a getaway weekend where you sat in a hot tub. What bacterial disease would a doctor suspect is causing your symptoms? Would the doctor suspect you contracted it from another person?

Answer 23

Legionnaires. No—legionella cannot be spread simply by direct contact between people. Legionella can only be transmitted through droplets small enough to be breathed in.

Question 24

True or False. Pneumonic plague is often characterized by painfully swollen lymph nodes.

Answer 24

False
Pneumonic plague targets the respiratory system while bubonic targets the lymph system.

Question 25

Which form of the plague is the most rare? What does it target?

Answer 25

Septicemic plague is the most rare and it targets the blood system.

Question 26

Identify the following disease:

Answer 26

Lyme disease
Lyme disease. The trademark ‘bulls-eye’ rash is a clear indicator.

Question 27

Syphilis is caused by:

Answer 27

Gram-Negative spirochete

Question 28

True or False. Chlamydia is an obligate parasite and as such can be grown on agar plates alone.

Answer 28

False
An obligate parasite requires a host (viable cells) to be present for its growth.

Question 29

Match the following diseases with their respective symptoms if left untreated:

1.Gonorrhea A. Paralysis, blindness and dementia
2. Syphilis B. Painfully swollen lymph nodes
3. Chlamydia C. Cardiac and neurological complications
D. Respiratory failure associated with lock-jaw
E. Infertility and pelvic inflammatory disease.
F. Sore throat, ocular discharge and fever

Answer 29

1C
2A
3E