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Microbiology > Unit 5 > Flashcards

Unit 5 Flashcards

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Biology 101 flashcards
1
Q

What is a microbiome

A

Total community of microorganisms in an environment or location on the body

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2
Q

What is normal flora

A

Microorganisms that are present either in or on an animal that is “healthy” that undergoes constant change

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3
Q

The relationship between normal flora and the host is described as

A

Symbiosis

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4
Q

What is symbiosis

A

An association of two or more different species of organisms

In microbiology this refers to:
Bacteria/fungi/yeast and animals/plants

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5
Q

What are ectosymbionts

A

Organisms that live on the host

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6
Q

What are endosymbionts

A

Organisms that live in the host

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7
Q

What is mutualism and give an example

A

Type of symbiosis When both organism benefits from the relationship

Ex. Rumen bacteria

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8
Q

What is commensalism

A

Type of symbiosis where only one of the organisms benefits from the relationship and the other is neither helped or harmed

The commensal is the organism that is helped

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9
Q

What is competition

A

Occurs when 2 or more organisms share a space and have to compete for the available resources (space and nutrients)

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10
Q

What are two possible outcomes of competition

A

One will out compete the other

Both will exists in lower levels

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11
Q

What are the 4 roles of normal flora

A

Aids in digestion
Provide essential nutrients
Stimulates the immune response
Protects against infection

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12
Q

Why is normal floras role in digestion important in ruminants

A

To digest insoluble fiber from plants

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13
Q

How does normal flora provide essential nutrients

A

GI flora synthesize vitamins and essential amino acids

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14
Q

How does normal flora stimulate the immune response

A

Maintains a low level of ongoing immune activity so they can respond faster to infection

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15
Q

How does normal flora protect against infection by more virulent microbes

A

Through competition

Altering pH to inhibit growth

Producing anti-microbial factors that prevent colonization

Maintain low level of immune activity

Bind to and block pathogenic bacteria from binding to receptors on cell surfaces

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16
Q

What are bacteriocins

A

Antimicrobial factors produced by normal flora

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17
Q

What are the 2 ways normal flora in controlled

A

Competition

Immune system: balance between immune system and normal flora

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18
Q

What are 3 instances of disturbance of the normal flora

A

When there is too much notmal flora

When there us too little normal flora

When normal flora moved to a new location it is not normally found

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19
Q

What is the most common cause of overgrowth of normal flora

A

Decreased function if the immune system

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20
Q

What are some other causes of overgrowth of normal flora

A

When normal flora moves to a new location

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21
Q

What is it called when normal flora cause disease

A

The normal flora are now called an opprotunistic pathogen

The disease is called an opprotunistic infection

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22
Q

What are the two examples of loss of normal flora

A

Can be a decrease in overall numbers of bacteria or decreased number of different species

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23
Q

What does a loss of normal flora result in

A

Lack of competition
Lack of bacteriocins
More space for pathogenic bacteria (allows colonization)

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24
Q

What are some examples of loss of normal flora

A

Oral antibiotics causes Clostridial enteritis

Loss if skin bacteria leads to yeast overgrowth

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25
Q

True or false

Animals grown in labs without normal flora have a very low risk of infection

A

FALSE

They have a very high risk

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26
Q

Where are normal flora found in the nose

A

Only in the nostrils

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27
Q

describe the normal flora in the oro-nasopharynx

A

Combination of aerobic or anaerobic bacteria, mostly non-pathogenic unless the get onto tissues that are sterile (sinuses, middle ear, brain)

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28
Q

Describe normal flora in the trachea

A

Transiently colonized by bacteria from the oronasopharynx, continually removed by the mucociliary elevator

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29
Q

What is the role of the mucociliary elevator

A

The mucus traps microbes and particles
Cilia on the mucosal epithelial cells sweep the mucus upwards to the oral cavity where it is spit out or swallowed

Keeps microbes out of the lower airways

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30
Q

What does damage to the trachea cause and what are some examples of possible damage

A

Viral infection, smoke inhalation

Increases risk of infection

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31
Q

Describe the normal flora in the lower respiratory tract

A

Generally sterile (no normal flora)

Transiently colonized by bacteria from the upper resp. Tract but often cannot establish

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32
Q

What are 3 ways microbes are continuously removed from the lower respiratory tract

A

Mucociliary elevator

Phagocytosis by alveolar macrophages (WBCs in alveoli)

Lysozyme in mucus (hydrolyzes bonds in peptidoglycans of bacteria)

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33
Q

What are some risk factors of microbial colonization in the lower respiratory tract

A

Acute or chronic aspiration

Damage to the mucus generating cells and cilia of the respiratory tract

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34
Q

What is acute or chronic aspiration from and what are the risk factors

A

Inhaling infectious materials into the lungs, normally from the oral cavity or esophagus/stomach

Increased risk with megaesophagus, gastroesophageal reflux, chronic vomit, cleft palate

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35
Q

What are some causes of damage to the mucus generating cells and cilia of upper respiratory tract

A

Traumatic/chemical injury (smoke inhalation)

Primary viral infections (kennel cough shipping fever in cattle)

Inflammation (asthma)

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36
Q

Why is there very few normal flora on the skin

A

Due to the hostile environment from:
Dryness
Oils (pH of sweat is antibacterial)
Sloughing of skin cells (also sloughs bacteria)

Tends to be transiently colonized

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37
Q

What are found in the moist areas of skin

A

Fungi (malasrzzia-yeast) in areas such as armpits, groin, and flank folds

38
Q

What happens to the normal flora with abnormal skin (warm or moist)

A

Increased bacteria and yeast which can cause pathology

Breach of intact skin allows bacteria to attach to underlying subcutis and proliferate

If yeast populations go into overgrowth it can causes disease (bacterial pyoderma - hot spots)

39
Q

What is the normal flora of hair, fur and wool

A

Contaminated by anything in the environment

40
Q

True or false

Hair, fur and wool is always considered a contaminant

A

True

41
Q

True or false

There are the same flora found in the external hair and the hair follicle

A

FALSE

they are DIFFERENT

42
Q

Can hair fur and wool support its own biofilm?

A

Yes, under certain environmental conditions on the fur

43
Q

Describe the normal Flora on the eye

A

There are always a small amount of bacteria present on the conjunctiva

Numbers are held in check by lysozyme in the tears

44
Q

Describe the normal flora on the external ear

A

Similar bacteria and yeast thats found on the skin, most commonly Staphylococcus

45
Q

Describe the normal flora of the mouth

A

Hundred to thousands of different species of microbes

Aerobic: on the teeth
Facultative anaerobes and anaerobes: on the peridontiun (in gums)

46
Q

What is bacterial plaque on teeth

A

A mat of microbes (biofilm) solidly attached to teeth

Can extend subgingivally if it extensive and will change from aerobic to anaerobic

47
Q

What increases risk of bacterial plaque on teeth

A

Enamel wears/scratches
Malocclusion
Diet high in fermentable carbohydrates
Poor hygiene

48
Q

Why are there small amounts of normal flora in the monogastric stomach

A

Because the stomach acid keeps it mostly sterile

49
Q

What is an iatrogenic cause of change in numbers of normal flora of the stomach

A

Antibiotics

50
Q

What does the normal flora of the rumen allow the cow to do

A

Digest and extract nutrients from cellulose (straw/hay/grass)

Allow animal to digest the microbes for macronutrients

Survive very harsh nutritional/environmental condistions

51
Q

Describe the normal flora in the rumen

A

10^12 microbes/ml (alot)

Composed of bacteria, protozoa, fungu, archaea, viruses

Mostly gram negative

E. coli is very common in normal flora

Anaerobic bacteria ferment the sugars to alcohols and acids that can be absorbed

Lactobacilli produce building blocks for milk sugar

52
Q

What are archaea

A

“Old” prokaryotic organisms

Make up 3% of microbial mass (separate from bacteria)

Convert hydrogen gas and CO2 to methane (by products of cellulose fermentation) (belched out)

53
Q

What are the viruses/bacteriophages in rumen flora

A

Bacteriophage are viruses that infect and kill bacteria

Causes cells to lyse, cell contents are then used as nutrients for the animal

54
Q

True or false

Colonization of the rumen is fast

A

FALSE

It is slow

55
Q

How are microbes of the rumen passed between aniamls

A

Nursing

Transfering cud

56
Q

What is the primary factor determining the bacteria profile of the rumen

A

Diet

57
Q

Why must diet changes be slow

A

Proper microbes required to digest the new diet take 2-3 weeks to establish

58
Q

What can you do to cause rapid colonization

A

Rumen fluid/microbe transfer

59
Q

Describe the normal flora in the small intestine

A

Very few numbers in the duodenum and increase in numbers as it moves distally to the cecum

Made of bacteria, fungi and protozoa

Mixture of anaerobes (more strict anaerobes vs facultative anaerobes)

May have small numbers of pathogenic bacteria (salmonella) which are associated with food poisoning

60
Q

What are the 6 functions of the small intenstine flora

A

Vitamin synthesis (vit K, B9 and B12)

Contributes to digestion (mainly fiber)

Enhance segmental contractions and peristalsis

Inhibit colonization by pathogenic bacteria (competition, bacteriocins)

Stimulates immune tissue in SI

Druge metabolism pathways

61
Q

Describe the normal flora of the large intestine (colon)

A

Has the largest microbial population in the body (10^11 bacteria/gram of feces)

Mostly anaerobic (strict and facultative)
Dominant species is E.coli

Colonization starts at birth with ingestion of birth canal secretions and feces or through nursing, changes with diet and inflammation of GIT

62
Q

What happens with significant loss of normal flora due to oral antibiotics

A

Tend to see clostridial overgrowth which leads to diarrhea and/or colitis

63
Q

What contributes to irritable bowel disorder

A

Lack of balance between normal flora and the immune system

64
Q

Describe coliforms

A 
Rod shaped
Gram negative
Motile
Non-spore forming bacteria
Can ferment lactose
Normally found in feces, water, soil, vegetation (indicates fecal contamination when in environment)
65
Q

What is small intestinal bacterial overgrowth (SIBO)

A

When normal flora of the small intestine starts to resemble the colon

Occurs when there is decreased peristalsis or damage to the cecum which allows large intestine flora to migrate to the small intestine

66
Q

What happens when there is colon flora in the small intestine

A

Creates gas, which causes distension

Interferes with digestion/absorption

Increased competition for nutrients

Results in inflammation, diarrhea, colic etc

67
Q

Describe the normal flora of the liver

A

STERILE

68
Q

What is biliary cholestasis and what does it cause in the liver

A

Lack of proper bile acid flow through the biliary ducts

Bacteria that was in the gall bladder could potentially enter the liver

69
Q

After death, what happens to the liver

A

There is rapid contamination of the liver from intestinal bacteria

70
Q

Describe the normal flora of the prepuce

A

Contaminated, also contains normal bacteria found on the skin and fur

Can harbor chronic asymptomatic pathogens not considered normal flora

71
Q

What bacteria does the vulva contain

A

Mix of bacteria found on vagina and skin

72
Q

What causes changes to the normal flora of the vagina and cervix

A

Cycling estrogen levels

73
Q

Describe normal flora of the distal urethra

A

Normal flora consistent with skin microbes

Colonization with normal flora from intestinal tract can cause disease

74
Q

Normal flora of proximal urethra and bladder in males

A

Sterile

75
Q

Normal flora of the proximal urethra and bladder in females

A

Supposedly sterile but is transiently colonized by flora from the distal urethra (very low numbers)

76
Q

Colonization in the proximal urethra and bladder is with microbes from the

A

Skin, fur, external genitalia and feces

77
Q

Why is there more colonization of the proximal urethra and bladder in females than males

A

Because of the shorter distance between the proximal and distal urethra in females

78
Q

How is colonization in urethra and bladder prevented

A

Flushing during urination

Distance from the outside

Urine pH inhibits growth (6.2-6.5)

Epithelial cells produce antimicrobial substances that inhibit bacteria from attaching and replicating

79
Q

What does urease do

A

Some bacteria produce urease which cleaves urea to increase pH of urine to make it more hospitable for colonization

80
Q

Describe the normal flora of the kidneys, ureters, prostate and uterus

A

Always sterile (any microbes present are considered pathogenic)

81
Q

What does the prostate secrete to protect from colonization

A

Produce its own prostatic antibacterial factors

82
Q

How is the uterus protected from colonization

A

The cervix

Production of acid from lactobacillus in vaginal mucosa (pH)

83
Q

What do changes in the cervix and vagina during estrus cause

A

An increased risk of bacteria entering the uterus

84
Q

What are STDs

A

When pathogens colonize in the genital tract

85
Q

Describe the normal flora of mammary glands in dry cows

A

Certain bacteria in the mammary galnds prevent colonization of teats with pathogenic bacteria

86
Q

Why are the mammary glands in milking cows at constant risk of infection

A

Milk is the ideal culture media

Trauma to the teat during milking allows bacteria to enter

87
Q

What are some internal tissues that are microbe free

A 
Brain, spinal cord 
Bone, muscles, joints 
Heart, blood 
Inside of the eyeball
Kidneys, liver, spleen
Peritoneum, pleural space
88
Q

What are some areas of the lower respiratory tract that are microbe fee

A

Bronchi
Bronchioles
Lung parenchyma

89
Q

What are some areas of the upper urogenital tract that are microbe free

A 
Proximal urethra and bladder 
Ureters
Kidneys
Uterus
Prostate
90
Q

What are Axenic animals (germ free animals) and how are they kept germ free

A

Animals that are totally free if microorganisms (no normal flora)

Animals is born by c-section under complete aspesis, transferred to sterile environment with sterile food, air, bedding and water

Used for research

Very high risk of infection in the normal environment

91
Q

What are gnotobiotic animals

A

Used for research, these are axenic animals that are exposed to only know, specific microbes

Results in animals with only known identities if normal flora and other microbes

Must be kept in sterile environments to prevent introduction of other microorganisms

92
Q

What are specific pathogen free (SPF) animals

A

Used for research, animals that do not have a specific microbe/pathogen

When that specific microbe is introduced to the animals, any changes are caused by that microve/pathogen

Microbiology (12 decks)

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