Microbio chapter 34

Which of the following statements regarding the relationship between diet and the gut microbiome is false?

A diet rich in red meat and high fat results in an overproduction of short-chain fatty acids.

Humans are holobionts; they contain approximately three times as many microbial cells as human cells. Recent metagenomic investigations reveal that human microbial flora is extremely diverse and is best described as ________.

vital to our survival

Determine the connection between the gut microbiome and the central nervous system.

-Imbalance in the gut microbiome upregulates the production of IL-17 a pro-inflammatory cytokine, which alters the function of neurons and microglia. -Bacteria can directly stimulate the neurons of the enteric nervous system that line the gut, sending a message to the brain via the vagus nerve. -Soluble microbial products impact the CNS by affecting the permeability of the blood-brain barrier.

Which of the following statements represents the influence the gut microbiota has on immune regulation and homeostasis?

-The gut microbiota sends signals that influence the morphology and migration of tissue macrophages. -The gut microbiota releases metabolites that affect circulating myeloid cells, ensuring their appropriate maintenance and removal. -The gut microbiota sends signals that influence the appropriate development of myeloid cells in the bone marrow.

Select all statements that accurately describe results obtained through the human microbiome project and other human microbiome studies.

-The human microbiome varies significantly among individuals. -Obesity is associated with limited microbial diversity in the gut. -The gut microbiome is essential in stimulating immune system maturation.

The Human Microbiome Project is evaluating the role the microbiome plays in human homeostasis. Which statement reflects the role the microbiome plays in homeostasis of the immune system?

-The normal microbiome competitively excludes pathogens for nutrients and space. -Antimicrobial peptides secreted by host Paneth cells requires the presence of gut flora. -Soluble factors, such as short-chain fatty acids like butyrate and acetate, produced by the gut microbiome influence immune cell maturation throughout the body.

A feasible use of probiotics in the future includes __________.

-a microbial preparation administered in hospital to prevent growth of a population of resistant bacteria -travelers taking a prophylactic dose of probiotics in preparation for a trip to a developing country that lacks strict food and water sanitation -post-antibiotic therapy, patients are given a dose of probiotics to repopulate the gut to normalize gastrointestinal and immune function

Which of the following areas of the human body is(are) not normally free of microorganisms?

-respiratory tract -intestinal tract -eyes

One proposed way probiotics may be used in illness prevention is __________.

-the administration of a consortia of organisms to outcompete infection-causing antibiotic-resistant bacteria -tourists taking a probiotic preparation in anticipation of a trip to an area lacking U.S. standards of food and water treatment -outpatients are given a cocktail of organisms to reconstitute a depleted microbiome following aggressive treatment, which promotes colonization resistance

Which of the following statements best defines the word "probiotic"?

A probiotic is a live microorganism, which, when administered in adequate amounts, confers a health benefit to the host.

Rationalize the following statement: "Toddlers who are administered frequent rounds of antibiotic treatment will suffer an inefficient immune system."

Antibiotics will kill the microbiome as well as any pathogens, which affects immune function since the microbiota release chemicals that affect the maturation and homeostasis of innate leukocytes.

Which of the following represents a direct mechanism of microbiome-pathogen colonization resistance?

Bacteriocins released by Gram-positive bacteria target closely-related species

Which of the following would you not find in the nasopharynx?

Branhamella catarrhalis

If the predominating microbiota of a particular human body site included Lactobacillus, Gardnerella, and Bacteroides, it would not be unusual to isolate which of the following genera as well?

Candida

A scientist wants to demonstrate the important relationship between an individual's microbiome and the healthy functioning of their central nervous system. Which experiment best supports their hypothesis?

Compared to conventional mice, germ-free mice demonstrate pathological behaviors in the areas of socialization, anxiety and depression, that can be normalized when populated with gut biota.

Which statement regarding the skin microbiome is correct?

Dry areas, such as the forearms and buttocks, host the greatest diversity of bacteria.

Which of the following would you expect to find in the tonsilar crypts?

Micrococcus

Why were the advent of metagenomics, and the application of molecular techniques such as single-cell and next-generation sequencing, important for defining a microbial relationship?

Newer methods revealed that symbiotic relationships exist between a host and one to thousands or more microorganisms, challenging the former definition of a symbiotic relationship as one that occurs between a single microbe and its host.

Recent research has demonstrated a correlation between the presence of certain types of Gram-positive bacteria in the human gut with obesity and type 2 diabetes. These findings best support which of the following statements?

Normal microbiota may significantly impact human health and disease.

A species of bacterium associated with the oil glands of the skin belongs to the genus ________.

Propionibacterium

Which of the following is not a benefit of bifidobacteria colonization in infants?

They provide a reducing environment to enhance the growth of aerobes

Under normal circumstances, the microbiota of the skin is kept in check by _________.

a slightly acidic pH

Holobionts ________.

are a collection of species that make up an ecosystem

Due to the acidic environment of the stomach, gastric juices ________.

contain a few viable bacteria per milliliter

The human microbiome ________.

evolves with humans over time

The adult female genital tract has a pH between 4.4 and 4.6. This is due to ________.

fermentation of glycogen by resident Lactobacillus

Microbes such as Lactobacillus acidophilus colonize the human vagina by fermenting .

glycogen

The importance of the human gut microbiota on metabolism is that ________.

human cells metabolize relatively few molecules into usable calories; most of our cellular energy is derived from microbial metabolism

Microbiota of the skin are most likely to be found _________.

in association with oil and sweat glands

Organisms of the microbiome that are acidophiles can be found ________.

in the stomach

A fundamental pathology of metabolic syndrome stems from __________.

insulin resistance

From which body region would you expect to isolate Clostridium, Bacteroides, Fusobacterium, and other anaerobic genera?

large intestine

What factors promote the colonization of bifidobacteria in the newborn?

limited oxygen in the intestines, and breast-feeding

Gram-positive bacteria such as Propionibacterium acnes limit the growth of Gram-negative bacteria and some fungi on the human skin by converting secreted ________ to compounds with antimicrobial activity.

lipids

Probiotics are __________.

live microorganisms, which, when administered in adequate amounts, confer a health benefit to the host

The microbial link between a diet rich in red meat and atherosclerosis is that ________.

microbes that thrive on high levels of L-carnitine produce trimethylamine, which is metabolized to trimethylamine N-oxide in the liver and has been shown to accelerate atherosclerosis in mice

Bifidobacteria are an essential component of host defense against pathogens and are required for ________.

normal development of GALT

Microorganisms commonly associated with the human body are traditionally referred to as the ________.

normal microbial flora or the normal microbiota

Organisms of the microbiome that are halophiles are predominantly found ________.

on the skin

Helicobacter pylori has been shown to cause cancer by __________.

producing CagA protein and injecting it into host cells, which leads to upregulation of genes that control cell proliferation, survival, migration, and blood vessel formation

From which of the following body sites would you expect to isolate Staphylococcus, Propionibacterium, Streptococcus, and Corynebacterium as the primary colonizing microbiota?

skin

The broad basis of the relationship between microbes and cancer in the human host is __________.

the ability of microbes to disrupt the normal cell cycle and to damage or mutate DNA

All of the following are true of holobionts except ________.

the microbial inhabitants of the host remain unchanged throughout the host's lifetime

The microbiota of the human large intestine ________.

varies at the level of the genus, rather than the phyla