Deck 26: Microbial Growth Control

Question 1

Erythromycin acts as a(n)

A) protein synthesis inhibitor at the level of the 50S subunit of the ribosome.
B) protein synthesis inhibitor at the level of the 30S subunit of the ribosome.
C) inhibitor of ribosome production.
D) nucleic acid enzyme inhibitor.

Answer 1

A

Question 2

Important targets of antibiotics in Bacteria are

A) the cytoplasmic membrane.
B) the cell wall.
C) DNA replication and transcription elements.
D) all of the above.

Answer 2

D

Question 3

The action of some bacteriolytic chemical agents can be observed by noting a(n)

A) decrease in the turbidity of the medium.
B) increase in the turbidity of the medium.
C) change in the color of the medium.
D) change in the surface tension of the medium.

Answer 3

A

Question 4

Highly active anti- retroviral therapy (HAART), which involves a combination of nucleoside analogs and protease inhibitors, is most commonly used to treat infections of

A) HIV.
B) drug resistant strains of bacteria.
C) Mycobacterium tuberculosis.
D) Staphylococcus aureus.

Question 5

Which statement is TRUE about heat sterilization?

A) Microbial death is more rapid at an acidic pH.
B) The amount of water in a substance is a major factor in heat resistance.
C) High concentrations of sugars and salts influence sterilization time.
D) All of the above are true.

Question 6

Of all the known antibiotics that have been identified in nature, are clinically useful.

A) 18- 20%
B) <1%
C) 8- 10%
D) 25- 30%

Question 7

Which is NOT a reason why microorganisms may have an inherent natural resistance to an antibiotic?

A) The organism may be able to alter the antibiotic to an inactive form.
B) The organism may be impermeable to the antibiotic.
C) The organism may be protected from the drug by its nuclear membrane.
D) The organism may be able to pump out an antibiotic entering the cell.

Question 8

Which of the following antimicrobial treatments is affective only on exposed surfaces?

A) ultraviolet rays
B) microwaves
C) X- rays and gamma rays
D) electrons

Question 9

In the agar diffusion method of studying antimicrobial action, the _ is measured.

A) distance between the microbial colonies
B) turbidity of the medium
C) diameter of the individual microbial colonies
D) diameter of the zone of inhibition

Question 10

Ergosterol inhibitors specifically target

A) viruses.
B) bacteria.
C) fungi.
D) eukaryotes.

Question 11

Semisynthetic antibiotics

A) are natural antibiotics that have been purified by artificial means.
B) are natural antibiotics that have been chemically modified in the laboratory.
C) have an artificially constructed core that stimulates the production of "natural products."
D) are found in nature, but their rate of production is enhanced in the laboratory.

Question 12

Polyoxins interfere with

A) cell membrane synthesis.
B) fungal mitosis.
C) chitin biosynthesis.
D) all of the above.

Question 13

Antimicrobial drugs are often grouped according to

A) mechanism of action.
B) molecular structure.
C) spectrum of antimicrobial activity.
D) all of the above.

Question 14

The time required for a tenfold reduction of the viability of a microbial population at a given temperature is called the time.

A) mean sterilization
B) temperature- dependent logarithmic death
C) thermal death
D) decimal reduction.

Question 15

The vegetative cells of Mycobacterium tuberculosis are resistant to many germicides because of

A) the complex nature of the plasma membrane itself.
B) an extra membranous layer between the cell wall and the plasma membrane.
C) the lattice work found in the glycocalyx.
D) the waxy nature of the cell wall.

Question 16

Agents that kill bacteria are said to be

A) bacteriostatic.
B) inhibitory.
C) bacteriocidal.
D) all of the above.

Question 17

Neuraminidase inhibitors such as oseltamivir and zanamivir are used to treat which type of infection?

A) fungal
B) influenza virus
C) parasitic
D) bacterial

Question 18

Compared with decontamination, disinfection is

A) less aggressive.
B) equally aggressive.
C) more aggressive.
D) either more or less aggressive, depending on the situation in question.

Question 19

Interferon is specific to the

A) host cell.
B) host cell and virus.
C) protein.
D) virus.

Question 20

Common radioactive isotopes for sterilization are

A) cobalt and potassium.
B) cobalt and iodine.
C) cobalt and cesium.
D) cesium and potassium.

Question 21

The most successful agents used for antiviral chemotherapy are

A) nucleotide analogs.
B) protein synthesis inhibitors.
C) nucleoside analogs.
D) ATP reductase inhibitors.

Question 22

At present, the penicillins and the cephalosporins account for of all the antibiotics produced and used worldwide.

A) less than 10%
B) over 50%
C) about 25%
D) well over 70%

Question 23

The complete elimination of all microorganisms, including viruses, is called

A) disinfection.
B) decontamination.
C) sterilization.
D) any of the above, depending on the circumstances.

Question 24

The production of interferon is stimulated by the presence of , which signals a virus infection in an animal cell.

Question 25

The thermal death time is the

A) time required for a tenfold reduction in the population density at a given temperature.
B) time it takes to kill all cells at a given temperature.
C) measure of the radiation energy output from a source.
D) dose of radiation necessary for a tenfold reduction in the numbers of selected microorganisms or biological functions.

Question 26

Radiation energy output is reported in units, and absorbed radiation dosage is measured in .

Question 27

The fi- lactam antibiotics

A) inhibit cell wall synthesis.
B) inhibit protein synthesis.
C) inhibit plasma membrane synthesis.
D) prevent chromosomal replication.

Question 28

The process by which macromolecules lose their structure and ability to function is called

A) thermal death.
B) sterilization.
C) denaturation.
D) none of the above.

Question 29

A filter is most often used to filter sterilize liquids.

A) membrane
B) microbistat
C) depth
D) nucleation track

Question 30

A _ filter is most often used in scanning electron microscopy.

A) microbistat
B) depth
C) nucleation track
D) membrane

Question 31

Cold sterilization is performed using

A) dry ice.
B) high- pressure chambers.
C) compounds such as ethylene oxide.
D) exceptionally low temperatures.

Question 32

Death from heating is a(n) function that proceeds more rapidly as the temperature rises.

Question 33

Antimicrobial activity is measured by determining the smallest amount of agent needed to inhibit the growth of a test organism, a value called the .

Question 34

Any chemical that kills or inhibits growth of a microorganism is called a(n) agent.

Question 35

The quinolones are synthetic antibacterial compounds that

A) increase the supercoiling rate in the bacterial DNA.
B) prevent the formation of pre- RNA segments.
C) inhibit bacterial DNA gyrase.
D) do all of the above.

Question 36

Pathogens are often encased and grow in large numbers as , covering the surfaces of tissues or medical devices with several layers of microbial cells.

Question 37

Which of the following are classified as electromagnetic radiation?

A) microwaves
B) X- rays and gamma rays
C) ultraviolet rays
D) all of the above

Question 38

are applied to living tissues; are used on inanimate objects.

Question 39

UV radiation is antimicrobial, because

A) radiation generates magnetic poles that denature the cellular components.
B) radiation generates significant amounts of heat within the given cell.
C) energy present causes modifications or breaks in the DNA molecules.
D) all of the above are true.

Question 40

The number of organisms present is termed the _ .

Question 41

Many Neisseria gonorrhoeae strains have developed fi- lactamases that cleave the fi- lactam rings, which provides them with resistance to certain antibiotics.

Question 42

The purpose of decontamination methods is to eliminate microbial growth.

Question 43

The act by inhibiting protein synthesis at the 30S subunit of the ribosome.

Question 44

The involves a lawn of bacteria on an agar plate exposed to small discs containing known amounts of antimicrobial agents.

Question 45

HEPA filters are an example of filters, which in the home are used to trap allergens, dust, and spores with a filter constructed from a random array of .

Question 46

Radiation is a decontamination measure approved by the World Health Organization (WHO) for foods particularly susceptible to microbial contamination.

Question 47

Endospore heat resistance is determined by the concentration of small acid- soluble proteins (SASPs) and water content of the endospore.

Question 48

Bacteriolytic agents can inhibit cell wall synthesis.

Question 49

Both cephalosporins and penicillins have the same mode of action, despite the two having different chemical structures.

Question 50

The term antimicrobial agent includes both fungicidal and fungistatic agents.

Question 51

fi- lactam antibiotics specifically bind to the _ that are essential in cell wall formation.

Question 52

Specific chemical substances required in the medium when organisms cannot synthesize them are known as ; structurally similar substances that block the utilization of these substances are known as .

Question 53

The tetracyclines are protein synthesis inhibitors that specifically disrupt the function of bacterial 30S ribosomes.

Question 54

Growth factor analogs that resemble nucleic acids are used in the treatment of viral and fungal infections.

Question 55

Most attempts at chemical control of viruses result in toxicity for the host.

Question 56

A thermometer can be sterilized using a cold sterilization method.

Question 57

The CDC has developed a 12- step prevention program for the prevention of resistance to antimicrobial agents aimed primarily for hospitalized individuals.

Question 58

The causative agent for rheumatic fever, scarlet fever, and strep throat is _.

Question 59

Like erythromycin and the aminoglycosides, inhibits protein synthesis.

Question 60

Cephalosporins contain a double fi- lactam ring, whereas the penicillins contain a single fi- lactam ring.

Question 61

Antiseptics may either kill or inhibit the growth of microorganisms and are sufficiently nontoxic to be applied to living tissues.

Question 62

Pasteurization is synonymous with sterilization; the only difference is that the term pasteurization is used with heat sensitive foods.

Question 63

The first widely used growth factor analogs specifically designed to inhibit bacterial growth were the sulfa drugs.

Question 64

Many countries, such as Australia, France, Germany, and the United States, decontaminate and sterilize certain foods with ionizing radiation.

Question 65

Describe an application of antibiotics other than their usage in clinical or veterinary medicine.

Question 66

In general, vegetative cells are more heat resistant than bacterial endospores.

Question 67

Explain what is meant by selective toxicity. How does selective toxicity relate to the development of chemotherapeutic agents?

Question 68

Explain the application of bacteriophage therapy, and provide a specific example of its use over antibiotics.

Question 69

Because of their limited range of effectiveness, the fluoroquinolones are used primarily in treating infections caused by gram- positive Bacteria.

Question 70

Isoniazid interferes with the synthesis of the mycobacterial- specific mycolic acid cell wall material.

Question 71

Describe an application or use for each of the following: antiseptic, disinfectant, germicide, sanitizer, and sterilant.

Question 72

Discuss the pros and cons of using radiation to sterilize items such as foods, drugs, and surgical supplies.

Question 73

Semisynthetic penicillins are generally more broad- spectrum than natural penicillins.

Question 74

Because of their particulate nature, electrons are not considered a form of electromagnetic radiation.

Question 75

Bacteriostatic agents inhibit bacterial growth but do not specifically kill the organisms against which they are directed.

Question 76

What are the pros and cons of flash pasteurization compared to bulk pasteurization?

Question 77

Drug resistance to the sulfonamides has remained low while many other types of antibiotics have remained constant.

Question 78

In practice, sterility is difficult to achieve.

Question 79

Describe the mode of action of the fi- lactam antibiotics.

Question 80

The antimicrobial effects of microwaves are due, at least in part, to thermal effects.