Chapter 14 normal human microbiota

immunocompromised host

can be repeatedly infected by normal microbiota (opportunistic pathogens)

they produce fatty acids that inhibit the growth of pathogens

How do microbes on the skin contribute to innate immunity? Choose one: A. They produce fatty acids that inhibit the growth of pathogens. B. They increase the bioburden of the host systems. C. They trigger the production of epinephrine when pathogens are present. D. They produce buffers to maintain the alkaline pH of the skin.

A and B

Increased indole production by intestinal microbes results in which of the following? Choose one or more: A. Increased production of anti-inflammatory products B. Increased tightness of tight junctions C. Quorum sensing D. Increased production of epinephrine

probiotics example

Lactobacillus and Bifidobacterium have been used to prevent and treat diarrhea in children

normal skin microbiota

Staphylococcus epidermidis, various Bacillus species, and yeast such as Candida

A decrease in microbiota diversity

The hygiene hypothesis postulates that the increase in asthma is caused by what? A. A decrease in traditional hygiene practices B. A decrease in microbiota diversity C. An increase in the presence of pathogenic bacteria D. An increase in synthetic foods

blood, cerebrospinal fluid, heart

Which of the following body compartments are sterile in healthy individuals? Choose one or more: A. Blood B. Cerebrospinal fluid C. Stomach D. Heart E. Oropharynx

tight junctions (Tight junctions form barriers that bacteria generally do not penetrate. These barriers maintain a healthy microbiome in the gut while preventing these bacteria from entering regions where they are pathogenic. Traumas to the tight junctions allow bacteria to cross, which can lead to opportunistic infections)

Which of the following characteristics of the epithelium of the digestive tract prevents opportunistic pathogens from entering deeper tissues? A. Bile salts B. Tight junctions C. Lesions in the epithelium D. Acidic pH

hormones

_____ such as epinephrine and norepinephrine, which are released following stress, can influence the composition of the intestinal microbiota

glycocalyx

a polysaccharide or peptide polymer secreted by organisms such as Streptococcus mutans, which attaches to tooth enamel, and Streptococcus salivarius, which binds to gingival surfaces, that firmly adhere to oral surfaces and to each other

penetration

accidental _____ beyond these normal sites can cause serious infections

risks of normal microbiota

accidental infection; the potential for developing new antibiotic resistant mechanisms; susceptibility to some metabolic diseases when the balance of microbial species is disturbed

hygiene hypotheis

aka the disappearing microbiota hypothesis

microbiome/microbiota

all the bacteria, archaea, fungi, and protozoa that inhabit our bodies

vegetations

are formed by a large number of bacterial cells encased within glycocalyx secreted by the organism (as a biofilm) and fibrin, produced by blood clotting

new diseases

as human health has improved in developing countries, unexplained ___ ________ have arisen (allergies!!)

evolve

bacteria and phages co-evolve, antibiotics do not______

quorum sensing

bacteria can communicate with each other using a variety of autoinducer molecules that they secrete themselves. these secreted molecules accumulate to the point where they can enter nearby bacteria of the same or different species. sensing these chemicals alters the expression of genes in the receiving species

dental procedures

can cause normal microbiota to enter the bloodstream, producing transient bacteremia(presence of bacteria in the blood)

bacterial vegetations

can colonize the heart(subacute bacterial endocarditis) and can cause a slow onset of symptoms

microbial metabolites

circulate our blood and influence human health and development

Helicobacter pylori

classic stomach pathogen that can resist acidic pH but will not grow at that pH. they can divide and survive in the mucous lining of the stomach and cause gastric ulcers and even cancer

eye

colonization is inhibited by the presence of antimicrobial factors such as lysozyme in the tears; skin flora are found on the conjunctiva

vaginal

composition of the ______ microflora changes wit the menstrual cycle, chasing nutrients and pH, and with the onset of menopause

blood brain barrier

comprised of very tight junctions between the endothelia cells of capillaries feeding the brain

yogurt

contains Lactobacillus acidophilus and a number of other lactobacilli that are part of a healthy gut microbiome. helps restore normal balance following antibiotic treatment

human intestine

distal parts of the ______ _________(ileum and colon) have slightly acidic pH 5-7; this is generally an anaerobic environment populated by both anaerobic and facultative microbe in a ratio of 1000 to 1

cause UTIs

distal urethra contains Staphylococcus epidermidis, Eneterococcus species, and some members of the Enterobacteriaceae, and they all can ______ if they make their way into the bladder

fecal transplant

extreme form of probiotics, where the intestinal microbiome of a healthy person is transferred to someone with a severe intestinal disease(IBD, colitis, C. difficile) to restore a normal microbiome

functions of the gut microbiota

fermenting unused energy substrates, training the immune system, preventing growth of pathogenic bacteria, regulating the development of the gut, producing vitamins for the host, producing hormones to direct the host to store fats

urination

flushes microbes out

microbial endocrinology

focused mainly on how pathogens respond to target host's hormones

phage therapy

idea that has returned because more strains of bacteria becoming resistant to antibiotics

oral cavity

infants mouth is colonized with nonpathogenic within hours of birth; as teeth grow in, anaerobic spaces in-between your teeth and gums support anaerobic organisms

skin

largest organ of the body; drying, acidity, secretions high in salt and low in water activity make it hard to colonize; mostly gram + colonize bc they tend to be more resistant to salt and dryness

respiratory tract

lungs and trachea do not harbor normal microbiota; upper tract contains microbes

immunomodulins

made by normal flora growing on mucous surfaces modify the secretion of host proteins that influence the immune response

probiotics

microbial competition has been widely exploited to improve human health in this process

mucous

microorganisms that make it to the trachea are trapped by ____

PCR to detect variations in DNA

most effective way to study microbes in the gut microbiome?

genitourinary tract

much of the tract is normally free form microbes; bladder harbors small number of microbes(mainly anaerobes)

pinkeye

occasionally Streptococcus pneumoniae, Haemophilus influenzae, as well as some viruses can cause an ocular disease known as

false

our microbiome stays the same from birth to death. true/ false

facultative

oxygen that diffuses from the intestinal wall into the lumen is consumed by the _____ microbes, rendering the environment anaerobic

gene expression

products of the microbiome can influence host _______

Enterotoxins

proteins produced by some gram - pathogens that damage the small intestine of the host and cause diarrhea

cytokines

small secreted host proteins that bind to various cells of the immune system and regulate their function

stomach

stomach contents are acidic and gastric activity can kill bacteria; the mucous lining is much less acidic and can hold some bacteria

False

the amniotic sac is sterile. true/ false

muscociliary escalator

the ciliated mucous lining of the trachea, bronchi, and bronchioles. constantly sweeps foreign particles up and out of the lungs.

virome

the entire population of viruses associated with the human body. little is known of their identities or impact on human health

epithelial cells

the major barrier separating us from our microbiota is a layer of these cells lining the mucosa of our digestive, genitourinary, and respiratory tracts

bioburden

the number of organisms that typically inhabit each ecosystem on the human body

benefits of our normal microbiota

they help us digest food; synthesize compounds; interfere with colonization of pathogens by competing for attachment sites, food sources, and synthesizing antimicrobial compounds; and they shape and enhance functions of the immune system

colonization

typically occurs where our body interfaces with the external environment (ex: mouth, skin, and part of the genitourinary tract)

antibiotic

use of this clears the body of good and bad microbial species, leaving voids that may be filled by species not as beneficial as those that were killed

bacteriophages

viruses that prey on bacteria. each bacteria species is susceptible to a limited number of specific phages, the phage can become part of the chromosome(lysogenic) or kill(lysis)