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our bodies carry more bacterial cells or human cells?
10x more bacterial cells than human cells
-
commensal organisms
bacteria found in nonsterile sites
-
intestine, mouth, skin, GI tract: lowest to highest anaerobe to aerobe ratio
intestine > GI tract > mouth and skin
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what conditions can change microbe population
- temperature
- humidity
- food consumed
- hygiene practices
-
skin is difficult to colonize because
lysozyme secretion
-
what bacteria can grow on skin
staphylococcus epidermidis
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what kind of bacteria is staphylococcus epidermidis
gram-positive
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at first, human infant's mouth is colonized with
streptococcus and lactobacillus
-
as teeth emerge mouth is colonized with
staphylococcus mutans: biofilm on tooth enamel
-
speticemia
bacteria causing disease after entering bloodstream
-
Helicobacter pylori
- survives at pH 1
- burrows into protective mucus
- causes ulcers
-
decreased stomach acidity is known as and caused by
- hypochlorydia
- malnourishment
-
vibrio cholerae
- survives stomach passage
- establishes infection in intestine
-
probiotics
- microbes ingested to restore the natural microbial balance
- common Bifidobacterium and lactobacillus
-
UTI is caused by
staphylococcus epidermidis in urethra
-
yeast infection is caused by
candida albicans
-
commensal microbes benefit human host by
- make vitamins and digest food
- prevent colonization of pathogens
- make immunomodulin proteins
- vaccine deliver vehicles
-
opportunistic pathogens
- cause disease when immune system barriers are breached
- host is immunocompromised
-
immune system is an integrated system of
organs, tissues, cells, cell products
-
nonadaptive (innate) immunity
- barriers to infection
- nonspecific responses to destroy invading cells
- present at birth
-
adaptive immunity
- reaction to specific antigens
- retains memory of antigens
- responds faster the second exposure
-
successful microbial attack must
- first, breach physical and chemical barriers
- second, survive innate defense and multiply
- third, overcome adaptive immunity
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