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)