Deck 23: Microbial Interactions With Humans

Question 1

The following bacterial species are all implicated in dental caries EXCEPT

A) Fusobacterium.
B) Borrelia.
C) Streptococcus.
D) Lactobacillus.

Answer 1

D

Question 2

Attenuation occurs in a laboratory,because

A) nonvirulent or weakly virulent mutants grow faster in vitro in laboratory media.
B) pathogens lose virulence with age.
C) patients are generally treated with drugs that induce attenuation.
D) None of the answers are correct.

Answer 2

A

Question 3

The decrease or loss of virulence of a pathogen is referred to as

A) aging.
B) attenuation.
C) disinfectivity.
D) lethal dose.

Answer 3

B

Question 4

Which of these microorganisms is MOST likely to be found in the human gut?

A) Helicobacter pylori
B) Streptococcus sobrinus
C) Streptococcus mutans
D) Roseobacter denitrificans

Question 5

Following antibiotic therapy,patients are often administered ________ to facilitate recolonizaton of normal flora.

A) fluoride
B) iron
C) probiotics
D) antivirals

Question 6

Pathogenicity is the ability

A) of the host to inflict damage on the pathogen.
B) of the host to resist damage by the pathogen.
C) of the pathogen to inflict damage on the host.
D) None of these are correct.

Question 7

Which of the following hemolysins is a phospholipase?

A) lecithinase
B) Streptolysin-O
C) Staphylococcal -toxin
D) leukocidin

Question 8

Only particles smaller than ________ µm in diameter reach the lungs.

A) 10
B) 20
C) 30
D) 40

Question 9

Normal flora in the duodenum are

A) similar to the microflora in the stomach.
B) dominated by aerobic organisms.
C) tolerant to alkaline environments.
D) tolerant to high salinity.

Question 10

The following compounds are all produced by intestinal microflora EXCEPT

A) flatus.
B) vitamin C.
C) vitamin B₁₂.
D) vitamin K.

Question 11

Which of the following is NOT a subunit of lipopolysaccharide (LPS)?

A) O-specific polysaccharide
B) lipid A
C) core polysaccharide
D) M protein

Question 12

One microenvironment of the skin is an area where glands produce an oily substance called

A) mucus.
B) sebum.
C) fimbrae.
D) lipid A.

Question 13

Capsules are particularly important for

A) making bacteria more vulnerable to host defense mechanisms.
B) making bacteria less pathogenic.
C) protecting bacteria from host defense mechanisms.
D) allowing bacteria to become more phagocytic.

Question 14

Which of the following are NOT found in the gastrointestinal tract of healthy humans?

A) Bacteroides
B) Clostridium
C) Escherichia coli
D) protists

Question 15

Decalcification of the tooth enamel due to the production of high concentrations of organic acids in the mouth is known as

A) degenerative plaque.
B) dental caries.
C) dental plaque.
D) microbial enamel decalcification.

Question 16

A polymer coat consisting of a dense,well-defined polymer layer surrounding a cell is called a

A) capsule.
B) glycocalyx.
C) lipopolysaccharide.
D) slime mold.

Question 17

Streptocoocus pyogens utilizes M protein and ________ to form microfibrils that facilitate attachment to host cells.

A) lipoteichoic acid
B) mucus
C) plaque
D) None of the answers are correct.

Question 18

Staphylococcus aureus produces ________,leading to fibrin clots that protect them from attack by host cells.

A) collagenase
B) coagulase
C) lipase
D) amylase

Question 19

Influenza virus targets

A) respiratory epithelium.
B) gastrointestinal cells.
C) oral cavity cells.
D) throat epithelium.

Question 20

The vagina of adult female is

A) highly acidic.
B) highly alkaline.
C) weakly acidic.
D) weakly alkaline.

Question 21

Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen?

A) malaria
B) measles
C) mumps
D) rubella

Question 22

Which of the following is the dominate genera of skin microflora?

A) Bacteriodes
B) Firmicutes
C) Actinobacteria
D) Proteobacteria

Question 23

Which genus produces hyaluronidase?

A) Mycobacteria
B) Streptococcus
C) Shigella
D) Procholorococcus

Question 24

A(n)________ is a damage or injury to a host organism that impairs its function.

A) trauma
B) infection
C) disease
D) transmission

Question 25

Normal flora ________ colonization of pathogenic organisms.

A) promote
B) prevent
C) maintain
D) accelerate

Question 26

Which of the following is an important factor in the development of dental caries?

A) high salt diet
B) high sugar diet
C) high acid diet
D) low salt diet

Question 27

Which of the following is more likely to cause urinary tract infections?

A) fimbriated strains of Escherichia coli
B) non-fimbriated strains of Escherichia coli
C) both fimbriated and non-fimbriated strains of Escherichia coli
D) None of the answers are correct.

Question 28

The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called

A) bacteremia.
B) cancer.
C) pathogenesis.
D) septicemia.

Question 29

Which of the following does NOT affect pathogen growth?

A) availability of microbial nutrients
B) pH
C) temperature
D) doubling time

Question 30

The human gastrointestinal tract includes all of the following EXCEPT the

A) small intestine.
B) stomach.
C) large intestine.
D) epiglottis.

Question 31

The collective term for the organisms living on or in the human body is

A) normal microbial flora.
B) fomite flora.
C) transient microbial flora.
D) pathogenic flora.

Question 32

Which of the following environmental and host factors influence the composition of resident microflora on the skin?

A) age
B) personal hygiene
C) weather
D) age, personal hygiene, and weather

Question 33

________ in saliva cleaves glycosidic linkages in peptidoglycan present in bacterial cell walls,weakening the wall and causing cell lysis.

A) Mucus
B) Lysozyme
C) Fibrin
D) Lipid A

Question 34

Pathogenic strains of Escherichia coli usually express

A) capsules.
B) colonization factor antigens (CFA).
C) plaques.
D) slime layers.

Question 35

Siderophores from some pathogens remove iron from the host protein(s)

A) lactoferrin.
B) transferrin.
C) both lactoferrin and transferrin.
D) cytochromes.

Question 36

Which of the following is a way to prevent attenuation and maintain virulence in a bacterium?

A) laboratory subculture
B) animal passage
C) polymerase chain reaction (PCR)
D) antibiotic therapy

Question 37

Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called

A) dental plaque.
B) dental caries.
C) dental biofilm.
D) periodontitis.

Question 38

Cytolytic toxins

A) are extracellular proteins.
B) cause cell lysis and death.
C) damage host cytoplasmic membrane.
D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

Question 39

Virulence is the relative ability of a ________ to cause disease.

A) pathogen
B) commensal
C) virus
D) bacterium

Question 40

Which of the following is NOT important for the adherence of bacteria to other bacteria as well as to host tissue?

A) adherence polymers
B) capsule
C) glycocalyx
D) slime layer

Question 41

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

A) Antigen dose₅₀.
B) Virulence-50.
C) LD₅₀ (lethal dose₅₀).
D) Death rate-50.

Question 42

Cholera begins following a bite from a mosquito.

Question 43

Virulence refers to the ability of an organism to cause disease.

Question 44

________ are toxic proteins released from the pathogen as it grows.

A) Endotoxins
B) Exotoxins
C) Macrotoxins
D) Microtoxins

Question 45

The condition that results when some organisms are shed in the bloodstream and distributed to distant parts of the body during bacterial growth in tissues is called

A) septicemia.
B) bacteremia.
C) uremia.
D) erythemia.

Question 46

________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts.

A) Healthcare-associated infections
B) Immunocompromised infections
C) Pathogenic infections
D) Virulent infections

Question 47

Which of the following pathogens does NOT require capsules or a slime layer for attachment?

A) Vibrio cholera
B) Streptococcus pneumonia
C) Bacillus anthracis
D) All of these pathogens require capsules or slime layers for attachment.

Question 48

Streptococcus mutans can produce dextran when sucrose is present in the absence of the enzyme dextransucrase.

Question 49

The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called

A) lipid A.
B) biofilms.
C) capsules.
D) glycocalyx.

Question 50

Pathogen virulence NEVER changes throughout a host's life.

Question 51

Which of the following is a category of exotoxin?

A) cytolytic toxin
B) lipophilic toxin
C) α-toxin
D) β-toxin

Question 52

A loose network of polymers extending outward from a cell is called a(n)

A) slime layer.
B) lipid A.
C) capsule.
D) adhesion.

Question 53

Protists are NOT normally found in the gastrointestinal tract of healthy individuals.

Question 54

An opportunistic pathogen causes disease ONLY in the presence of normal host resistance.

Question 55

Which of the following is a major growth-limiting micronutrient that influences microbial growth?

A) iron
B) transferrin
C) lactoferrin
D) sugar

Question 56

Bacteria found in the mouth in the first years of life are well-adapted to biofilm formation.

Question 57

The process by which microorganisms cause diseases is known as

A) pathogenesis.
B) virulence.
C) LD₅₀ (lethal dose₅₀).
D) infection.

Question 58

ALL microorganisms that live in the human body are harmful.

Question 59

Normal microflora are usually found in the blood,lymph,and nervous systems of the body.

Question 60

The process by which white blood cells ingest and kill bacteria is called

A) exocytosis.
B) transcription.
C) phagocytosis.
D) translation.

Question 61

When does an infection become a disease?

Question 62

The upper respiratory tract usually has a considerable amount of resident microflora in a healthy adult.

Question 63

Clostridium botulinum cannot produce toxins in improperly preserved foods.

Question 64

Animals that lack CXCR4 and CCR5 proteins are immune to HIV infection.

Question 65

Explain how diet plays a role in host susceptibility to infection.

Question 66

The number of Vibrio cholera cells necessary to produce cholera in an exposed individual is drastically reduced if the individual is malnourished.

Question 67

Gram-positive bacteria produce endotoxins.

Question 68

Malassezia spp.are the MOST common fungi present on the skin of humans.

Question 69

The toxic lipopolysaccharides produced by MOST gram-negative bacteria are called exotoxins.

Question 70

The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

Question 71

Bacteria make up about one-third the weight of fecal matter.

Question 72

Endotoxins are released in large amounts only when cells lyse.

Question 73

Why are some microorganisms specialized to only certain parts of the body? Describe an example that supports your answer.

Question 74

Vaginal acidity in the adult female is due to acid production by Lactobacillus acidophilus.

Question 75

Hormones that are produced under stress boost normal immune responses and play a role in stress-mediated disease resistance.

Question 76

Diphtheria toxin inactivates elongation factor 2 by catalyzing the attachment of adenosine diphosphate ribose from NAD⁺.

Question 77

Design an experiment to determine whether a potential pathogen produces hemolysins.

Question 78

Clostridium botulinum are endospore-forming bacteria normally found in the soil.

Question 79

R plasmids help prevent the spread of virulence factors.

Question 80

Invasion is the ability of a pathogen to enter into host cells or tissues,spread,and cause disease.