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Microbiology 1 > Lecture #12 - Medical Microbiology > Flashcards

Lecture #12 - Medical Microbiology Flashcards

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Biology 101 flashcards
1
Q

Human Microbiome

A

The collection of all the microorganisms living in association with the human body (microflora, microbiota)

FORM PART OF YOU - IN ADD. TO YOUR CELLS

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2
Q

Number of human cells in the human body

A

~ 10^13

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3
Q

Number of microorganisms in the human body

A

~ 10^14

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4
Q

Number of genes in the human genome

A

~ 20,000

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5
Q

Number of genes in the microbiome

A

~ 20,000,000

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6
Q

___ cells are numerically dominant in body

A

bacterial

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7
Q

Diff in # of cells in human microbiome creates

A

diff in chem characteristics you anticipate

  • fact that these organisms numerically out# you is 1 attribute, but fact they all bring such a diverse aray of diff genes means they’re changing your chem all of the time (prod. waste product that’re gonna have chem characteristics that change you, taking away nutrients from your body that’re gonna deplet certain things that would’ve provided certain characteristics)
  • all of this is H-bonding, ionic int’s, disulfide bonds, VdW’s int’s - chemicals can engage with 1 another & that creates differences in your body b/c of your beh that would never have happened if weren’t there
    • changes are not all good (play role in positive health & disease)
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8
Q

Colonization begins

A

immediately after birth
- start out as a sterile entity - vaginal bact is 1st to colonize you, C-section 1st exposure to is diff (breast feeding vs formula feeding changes type of flora that est. in GI tract & diff elements of immunity)

  • Diversity of species present varies greatly between individuals
  • Relative proportions also differ

even if 2 ppl have E. coli, the # can be diff in each person

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9
Q

Every exposed area in/on the surfaces of the body are colonized with bacteria

A

• Skin and mucous membranes

b/c outside world is dirty

RT, repro T, DT - have 1 or more openings to outside that can get contaminated

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10
Q

Internal tissues should be free of microbes

A
  • Serous membranes - peritoneum, pericardium, pleura

* Blood (not sterile based on metagenomic analysis), muscles, organs

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11
Q

Peritanitis

A

inflammation of peritoneum (life-threatening) b/c let bact move everywhere if cut

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12
Q

Most are harmless commensals

• Few contribute to disease - opportunistic pathogens

  • Many contribute to health
  • Produce beneficial products:
A

E. coli in the colon produces (a blood clotting factor) vitamin K

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13
Q

Many contribute to health

Inhibit the growth of pathogens

A

Ex. Lactobacillus acidophilus (produced LACTIC ACID - beneficial) acidifies and (LOWERS pH) protects the female reproductive tract (so its susceptible to STI’s – pH ~4.5)

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14
Q

Skin Microbiota

A
  • Different areas of the skin vary in chemical composition and moisture content
  • Provides 3 different microenvironments:
  • Dry skin, moist skin and sebaceous skin (sebum - oil – oily skin)
  • Each with different microbial populations
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15
Q

Skin Microbiota

Dry skin

A
  • Forearms, hands
  • High numbers of BETAproteobacteria
  • Known from 16 rRNA genes (metagenomic analysis)
  • Rarely cultured and their role isn’t known - *look out for themselves - microbial antagonism (produce poisons to kill others) & competitive exclusion (sole presence is gonna work to eliminate ability for other organisms to thrive)

• Second highest is CORYNEBACTERIA

  • MOST are HARMLESS commensals
  • SOME may cause SKIN INFECTIONS
    • Ex) Corynebacterium diphtheriae (*respiratory pathogen)
  • – Can cause NON-HEALING ulcers of the skin: cutaneous diphtheria (rubbery - scar tissue)
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16
Q

Skin Microbiota

• Moist skin

A
  • Armpits, nostrils (HIGH abundance of moisture)
  • High numbers of CORYNEBACTERIA and STAPYLOCOCCI
  • Most are HARMLESS commensals
  • Ex) Staphylococcus epidermidis (from normal flora on skin surface)
    • Most frequently isolated from skin

• Some are important PATHOGENS

  • Ex) Staphylococcus aureus
    • Cause of boils, abscesses, wound infections
  • HOST HEALTH & BACTERIAL VIRULENCE FACTORS DETERMINE THE OUTCOME (immunocompromised or not)
17
Q

Skin Microbiota

• Sebaceous skin

A

• Oily skin around the nose, on the upper chest and back
(SEBUM = oil produced by sebaceous glands associated with hair follicles)
• High numbers of PROPIONIBACTERIA
- ANAEROBIC ACTINOBACTERIA that produce PROPIONIC ACID (acidic waste) as an end-product of fermentation
– Ex) Propionibacterium acnes
— Lives in hair follicles, and eats oil secreted by skin (sebum)
— Overgrowth can trigger INFLAMMATION
—- Inflammatory acne

18
Q

Explain formation of Propionibacterium acnes

A

oil secreted from sebaceous gland by hair follicle

P. acnes (ANAEROBIC) - finding anaerobic pockets & feeding off oil there will INCREASE its # & gets attention of immune system which causes inflammation (inflammatory acne)

19
Q

What are 2 things someone with inflammatory acne do?

A
  1. ANTIBIOTICS - LOWER microbial count so you don’t have as much inflammation/immune activation
  2. TAKE DRUGS THAT LESSEN SEBUM (OIL) PRODUCTION –> LESS LIPID to metabolize –> can’t grow as much (no need for immune system to turn on to same degree)
    - OUTCOME: reduce food supply so organism is not able to thrive

washing face helps b/c breaks up sebum layer - then food source is taken away so organism doesn’t have anything to thrive on (if it eats its not eating a feast, its less)

20
Q

Microbiota of the Mouth

SALIVA has antimicrobial enzymes:

A

dirty b/c open to outside

• LYSOZYME - destroys PD chains
• LACTOPEROXIDASE
- CATALYZES production of superoxide radicals O2- *[HIGH] of oxygen radical = poisonous to the organism
- Oxidative damage to invading microbes

21
Q

Microbiota of the Mouth

The mouth is home to a complex microbial community including aerobes and anaerobes:

A

Ex) Neisseria mucosa
• AEROBIC
• Lives on mucous membranes like the TONGUE

22
Q

Microbiota of the Mouth

Streptococcus mutans

A

• AEROTOLERANT ANAEROBE
• Produces a sticky dextran SLIME LAYER that lets it STICK to surfaces (overnight, organisms have used the plaque & undigested nutrients left over, in order to facilitate replication - to feed themselves & promote their growth)
• Forms BIOFILMS (microbial community they’ve formed when given all this time to populate without being flushed away) in crevices around the teeth
• PRODUCES LACTIC ACID as an end-product of
fermentation (b/c no ETC)
• Degrades tooth enamel
• Dental carries (cavities) –> L.A wears away tooth if it hits pulp cavity (nerves & BV’s) then you do root canal & clear it out (tooth now dead) & cap it out so have physical support & help with chewing)
• Can lead to inflammation along the gum line:
• GINGIVITIS

23
Q

If someone has a likelihood to form cavities from bact in teeth b/c of L.A. buildup, they’re….

A

LESS likely to develop gingivitis b/c of pop. they have

24
Q

1 that has a lot of flora that support formation of gingivitis,

A

won’t likely be getting a lot of cavities b/c bact are diff in terms of their proportion & what it is that they’re doing

25
Q

Microbiota of the Gastrointestinal Tract

The stomach

A
  • Low pH (*HCl pH 1) and proteolytic enzymes (PEPSIN - digest protein, breaks peptide bonds) make the stomach inhospitable to most microbes
  • Some bacteria do colonize the (crazy conditions of) stomach
26
Q

Microbiota of the Gastrointestinal Tract
• The stomach
Ex) Helicobacter pylori

A
  • Cause of STOMACH ULCERS
  • Colonizes surface OF the MUCOUS MEMBRANE
  • Membrane is protected from stomach acids by MUCOUS (mucous layer that has HCO3-, so surfaces of stomach are protected against your own harsh digestive envir.)
  • bact can feed off of mucous mem (glycoprotein) for nutrients
  • Has a number of virulence factors:
  • (PRODUCES) Urease neutralizes surrounding acidity
  • Exotoxin: kills cells of the mucous membrane
  • Endotoxin: triggers an inflammatory response
  • B/C GRAM -

• Treated with antibiotics – TETRACYCLINE
& also use proton pump inhibitors (decrease amount of acid stomach is able to make so its less acidic - less harsh envir. that cause less of this ulceration)

27
Q

Ex) Helicobacter pylori is

A

CARCINOGENIC BACTERIUM
- b/c of way it causes ulceration & what it does to chem of stomach

b/c it does so much damage b/c stomach’s chem with its mucous is removed - you get HOLES inside stomach (ulcer)

  • stomach tries hard to fix –> sometimes leads to dev. of cancer b/c so much gene replication in such HIGH proportion
  • declared a carcinogenic bacterium

Microbiology 1 (15 decks)

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