Deck 14: Normal Human Microbiota: a Delicate Balance of Power

Question 1

Why do individuals take probiotics?

A) to directly kill intestinal pathogens
B) to secrete hormones that lead to weight loss
C) to provide a more fermentative environment
D) to restore balance to the microbial community

Answer 1

D

Question 2

________ is consistently sampling normal bacteria of the host to maintain a low-level immune response.

A) A tight junction
B) Lymphoid tissue
C) An epithelial cell
D) An endothelial cell

Answer 2

B

Question 3

The presence of ________ is essential for preventing respiratory infections.

A) bacteremia
B) epidermis
C) vegetations
D) the mucociliary escalator

Answer 3

D

Question 4

Why do the residents of our normal microbiota not regularly invade other tissues of the body?

A) They are inhibited by pathogens.
B) They have not evolved the ability.
C) They are not able to survive in other tissues.
D) Our normal microbiota does regularly invade other tissues of the body.

Question 5

Which of the following is NOT an accurate description for epithelial cells?

A) interconnected
B) symmetrical
C) held together by tight junctions
D) glycoprotein-covered

Question 6

Which microbial reservoir has the largest anaerobe to aerobe ratio?

A) intestine
B) genitourinary tract
C) mouth
D) skin

Question 7

Which of the following can act as an immunomodulin?

A) cytokines
B) enterotoxins
C) catalase
D) hydrogen peroxide

Question 8

A noninfectious disease that can be linked to changes in the microbiota is

A) yeast infection.
B) C. difficile infection.
C) irritable bowel syndrome.
D) stomach flu.

Question 9

Which of the following would NOT be a good organism choice for a vaccine delivery system?

A) Streptococcus salivarius
B) Lactobacillus acidophilus
C) Staphylococcus epidermidis
D) Staphylococcus aureus

Question 10

Which of the following is an optimal pH for the growth of Helicobacter pylori,a common inhabitant of the human stomach?

A) pH 1
B) pH 3
C) pH 5
D) pH 7

Question 11

________ is capable of passing through the placental membrane and endothelial cells to infect the developing fetus.

A) Influenza virus
B) Listeria monocytogenes
C) Staphylococcus aureus
D) Hepatitis B

Question 12

________ is/are used to study host-microbiota relationships in the laboratory.

A) Tight junctions
B) Metagenomics
C) Gnotobiotic animals
D) Quorum sensing

Question 13

Which of the following is evidenced by the health of gnotobiotic mice?

A) Antibiotic resistance is an ever-growing threat.
B) The presence of normal microbiota challenges the immune system.
C) Epithelial barriers prevent the spread of opportunistic infections.
D) Nothing has been learned from gnotobiotic mice.

Question 14

________ can completely change the intestinal mix of microbes.

A) Rashes
B) Sun exposure
C) Antibiotic treatments
D) Gnotobiotic delivery

Question 15

Which of the following situations demonstrates the risk of a microbiome?

A) Mary suffers from colon cancer. While being treated, she develops an opportunistic Bacteroides fragilis infection.
B) Andy is lactose intolerant. His body does not break down lactose, so the microorganisms in the gut do it for him.
C) Jenna is prone to yeast infections, so she routinely eats yogurt and takes a probiotic supplement to increase the amount of lactic acid bacteria in her vagina.
D) Anthony suffers from debilitating diarrhea after a lengthy course of antibiotics to treat his MRSA infection.

Question 16

Which of the following is NOT a useful function of the gut microflora?

A) fermenting unused energy substrates
B) training the immune system
C) supporting the growth of pathogenic bacteria
D) regulating the development of the gut

Question 17

The blood-brain barrier is composed of

A) arteries.
B) glycoproteins.
C) tight junctions.
D) very tight junctions.

Question 18

When do anaerobes begin to colonize the human oral cavity?

A) when teeth emerge
B) in the womb
C) during birth
D) during the first feeding

Question 19

In addition to digested food,where do carbohydrates come from in the large intestine?

A) mucus secretions
B) dead cells
C) saccharolytic fungi
D) arteries

Question 20

What would be the expected aerobe to anaerobe ratio of the belly button?

A) 10:1
B) 1:10
C) 1:100
D) 1:1000

Question 21

Which of the following forms of treatment do(es)NOT evolve as pathogens evolve?

A) phage therapy
B) fecal transplant
C) probiotics
D) antibiotics

Question 22

Which was developed first?

A) fecal transplants
B) probiotics
C) antibiotics
D) phage therapy

Question 23

Lipopolysaccharides,flagellin,and double-stranded DNA are microbe-associated molecular patterns recognized by

A) tight junctions.
B) ribosomes.
C) tumor necrosis factors.
D) pattern recognition receptors.

Question 24

Which of the following is NOT an argument for the consideration of the microbiome as a separate organ system?

A) There are ten times more microbial cells than human cells in the body.
B) Microbiomes are contained in defined and relatively independent parts of the body.
C) Defects in microbiome composition can have dire effects on human health.
D) A human microbiome is inherited from the mother and father.

Question 25

Endothelial cells are known for using ________ to carry cell components from one side of the cell to the other.

A) protein secretion
B) active vesicle transport
C) cytokine production
D) ATP synthesis

Question 26

Which of the following statements regarding quorum sensing is true?

A) Gene expression is altered when the population of a specific microorganism is low.
B) Gene expression is altered when the population of a specific microorganism is high.
C) There is no relationship between quorum sensing and gene expression.
D) Quorum sensing is a phenomenon very few organisms are capable of accomplishing.

Question 27

Examine the figure shown.Which Toll-like receptor is activated specifically by viruses?

A) TLR 9
B) TLR 5
C) TLR 4
D) TLR 3

Question 28

How has the development of clean water NEGATIVELY affected modern civilization?

A) reduced fecal transmission of bacteria resulting in missing microbiota
B) altered immunological environment
C) increased transmission of hormone-activating compounds
D) decreased amounts of important trace minerals

Question 29

Where are microbial metabolic end-products found in the body?

A) in the blood
B) in the urine
C) everywhere
D) nowhere

Question 30

Which of the following pathologies can develop when the gut microbiome organ is deficient?

A) pneumonia
B) yeast infection
C) inflammatory bowel disease
D) ulcers

Question 31

________ once colonized 80% of individuals in the United States and now only colonizes 10%.

A) Helicobacter pylori
B) Staphylococcus aureus
C) Salmonella typhimurium
D) Lactobacillus acidophilus

Question 32

What is problematic about treating bacterial infections that have spread to the brain?

A) You have to be careful not to harm the good bacteria of the brain.
B) Neurons in the brain will degrade antibiotics.
C) Many antibiotics are not capable of penetrating the blood-brain barrier.
D) Bacterial infections do not spread to the brain.

Question 33

How do naturally occurring Staphylococcus strains inhibit the growth of pathogenic strains?

A) producing antibiotics
B) producing short-chain fatty acids
C) outcompeting for nutrients
D) They do not inhibit pathogenic strains.

Question 34

Which of the following is NOT a current or possible future fecal transplant method?

A) colonoscopy
B) endoscopy
C) blood infusion
D) capsule ingestion

Question 35

________ is the preferred carbon source for epithelial cells.

A) Glucose
B) L-DOPA
C) Norepinephrine
D) Butyrate

Question 36

Examine the figure shown.Which Toll-like receptor is activated specifically by Gram-positive organisms?

A) TLR 4
B) TLR 3
C) TLR 2
D) TLR 1

Question 37

Observe the figure shown.Based on what you see,what can you conclude?

A) Norepinephrine stimulates biofilm formation of Staphylococcus epidermidis.
B) Norepinephrine is inhibited by Staphylococcus epidermidis.
C) Staphylococcus epidermidis is able to use norepinephrine as a carbon source.
D) Norepinephrine has no effect on Staphylococcus epidermidis.

Question 38

Many of the genes affected by colonization with Eubacteria rectale and Bacteroides thetaiotamicron are involved with

A) the blood-brain barrier.
B) energy production.
C) colonic turnover.
D) pro-inflammation.

Question 39

Which of the following changes in human behavior has NOT altered the composition of the microbiota?

A) decreased antibiotic usage
B) increased cesarean deliveries
C) living in smaller families
D) use of antibacterial soaps

Question 40

Use of preterm antibiotics during labor and delivery has led to

A) reduced fecal transmission of bacteria.
B) an altered immunological environment.
C) reduced vaginal transmission.
D) accelerated change of skin microbiome.

Question 41

Label the figure shown.

Question 42

The blood-brain barrier is comprised of ________ between the endothelial cells of capillaries feeding the brain.

Question 43

Give three reasons for why the microbiome should be considered an independent organ system.

Question 44

Fecal transplants can be used to treat ulcerative colitis caused by ________.

Question 45

CASE HISTORY
Hiroshi,a 19-year-old college student,arrived at the emergency department complaining of a fever and lethargy that started the previous evening.He originally suspected that the symptoms were due to a hangover from a fraternity party held two days earlier.However,Hiroshi became alarmed when turning his head became painful and when tiny red blotches suddenly appeared on his skin.The physician recognized this as a petechial rash (red spots on the skin that do not blanch,or turn white,when pressed).Blood cultures were obtained,and Hiroshi underwent a lumbar puncture to obtain cerebrospinal fluid (CSF)for culture.He was immediately admitted to the hospital and treated with intravenous antibiotics.The next day,blood and CSF cultures grew a deadly Gram-negative diplococcus-Neisseria meningitidis.Hiroshi had bacterial meningitis.
Explain the natural barrier Neisseria meningitidis must have crossed in order to result in Hiroshi's meningitis.Briefly,how does this barrier serve as an immune defense so effective some people can be asymptomatic carriers of this bacterium?

Question 46

Probiotics have been used in baby chicks to prevent colonization by ________.

Question 47

Explain how a nonpathogenic organism like Staphylococcus epidermidis present in the lungs of an individual with cystic fibrosis can still cause problems.

Question 48

Colonization of the stomach requires the ability to withstand ________ conditions.

Question 49

The presence of a core ________ is most important for a healthy microbiome.

Question 50

What is wrong with the situation described below?
After vaginal delivery,a gnotobiotic mouse was moved to an axenic environment.

Question 51

Describe the positive and negative side of enterotoxins.

Question 52

Sequestered body sites tend to be ________.

Question 53

Explain the disappearing microbiota hypothesis and how it can explain why individuals who attended day care as adolescents tend to suffer fewer allergies than individuals who did not.

Question 54

CASE HISTORY
Renita,a 67-year-old woman,complained to her physician of having persistent diarrhea with weight loss,bloating,and excess flatulence (passing gas).Renita also said her stools looked greasy,which the physician knew as a sign that ingested fat was not being absorbed.A blood test revealed that the woman's vitamin B₁₂ level was abnormally low.Cultures of fecal specimens failed to find any typical bacterial pathogens that could cause diarrhea.However,the decreased vitamin B₁₂ level and excess fat in the stool suggested that the woman had a malabsorption disease.The physician,initially perplexed,suddenly realized that the cause could be small intestine bacterial overgrowth disease,a diagnosis confirmed by aspirating fluid from the jejunum (small intestine).The laboratory discovered abnormally high numbers of facultative and anaerobic bacteria in the fluid,including Streptococcus,Escherichia coli,Lactobacillus,and Bacteroides.Fermentation by these organisms produced the bloating and flatulence.Antibiotic treatment corrected the syndrome.
Which best describes the relationship between Renita and her microbiome in this case study?

A) Pathogens were present in Renita's jejunum in addition to normal microbiota.
B) Previous antibiotic use disrupted Renita's normal flora, allowing overgrowth of resistant species.
C) Renita's immune system was unable to reduce the growth of bacteria in her GI tract, leading to overgrowth of all the bacteria in her microbiome.
D) A physiological change such as reduction of bile production allowed microbiota from one portion of Renita's GI tract to thrive in another, inappropriate area.

Question 55

Explain two potential negative effects of using phage therapy to treat bacterial infections.

Question 56

________ are organisms that cause disease in an immunocompromised host only.

Question 57

A nonmotile Gram-negative organism has breached a tight junction barrier.How will this organism be detected and what will happen immediately inside the host to protect it from infection?

Question 58

Production of indole by E.coli tells host intestinal epithelial cells to tighten tight junctions and increase production of ________.

Question 59

The presence of Eubacteria recale and Beta thetaiotamicron affect ________ of the host.

Question 60

Give an example of how our cells communicate with the microbiome.

Question 61

CASE HISTORY
A tiny 1-kg (2.2-pound)female neonate (newborn)was born two months premature.The baby had extreme difficulty breathing and had to be intubated (a breathing tube inserted).The mother,at the time of admission,had complained of mild diarrhea and abnormal abdominal pain unrelated to her pregnancy.The infectious disease doctor who was called in to consult on the case immediately recognized the likely problem and ordered blood cultures be performed on the infant.The infant was also started on intravenous antibiotics.Two days later,the lab reported finding a Gram-positive bacillus-Listeria monocytogenes-in the infant's blood.This same organism was the cause of the mother's diarrhea.The mother had unwittingly ingested some unpasteurized cheese contaminated with this pathogen and developed listeriosis.The organism entered the mother's bloodstream and was transmitted across the placenta to the fetus prior to birth.
The maternofetal or placental barrier is a mechanism that helps to protect the fetus from infection during its development.The adult human has several regions with similar levels of innate resistance to pathogen transfer.Compare and contrast at least one additional barrier that separates the natural microbiome from its host to the maternofetal barrier.