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Microbiology pt.1 > Microbiome > Flashcards

Microbiome Flashcards

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1
Q

human microbiome

A
  • around 100 trillion prokaryotic and euykaryotic microorganisms
  • Microorganisms of the human microbiota have more than 5 million genes

→ second genome called microbiome

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2
Q

benefits of the microbiota of the human body

A
  • metabolism of food products
  • provides essential growth factors
  • protects against infections with highly virulent microorganisms
  • stimulates the immune response
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3
Q

Exposure of an individual to microorganisms can lead to one of three outcomes:

A

1) transient colonization of the person;
2) permanent colonization of the person;
3) production of the disease

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4
Q

Disease due to m.o.s

A
  • Microorgs that colonize humans (whether for a short period or permanently) do not interfere with normal body functions
  • Disease occurs due to a pathologic process characterized by damage to the human host
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5
Q

Strict pathogens

A
  • cause few infections

- always associated with disease

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6
Q

most human infections are caused by

A

opportunistic pathogens -> typically members of humans normal flora but can produce disease when they are introduced into unprotected sites (blood,tissues)

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7
Q

microbial flora of human skin

A
  • environment of skin does not support the survival of most m.o.s
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8
Q

most common organisms on skin surface

A

gram positive bacteria

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9
Q

which bacterium is found on 20% of healthy individuals?

A

clostridium perfringens

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10
Q

What type of fungi are found on moist skin surfaces?

A

fungi candida and malassezia

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11
Q

what did the human microbiome project find out?

A

→ uncultureable gram- negative rods may be the most common microorganisms on the skin surface

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12
Q

what type of bacteria aren’t commonly cultured from human skin?

A

gram negative rods

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13
Q

Whats the most common type of bacteria on the outer ear?

A

coagulase-negative staphylococcus

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14
Q

Which ones are also potential pathogens of the ear and eye?

A

S. pneumoniae, Pseudomonas aeruginosa, and members of the Enterobacteriaceae family

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15
Q

What colonizes the surface of the eye?

A

coagulase-negative staphylococcus

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16
Q

Which bacteria can be rarely found in the nasopharynx?

A

e.g., Haemophilus spp., Neisseria spp., viridans streptococci

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17
Q

Where can relatively avirulent and rarely associated with disease, bacteria be dangerous?

A
  • in normally sterile sites (sinus, middle ear and brain)
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18
Q

What are the most common bacteria of the upper respiratory tract?

A

Streptococcus, Haemophilus, and Neisseria spp

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19
Q

Which m.o.s can be potentially pathogenic ?

A
  • streptococcus pyogenes, streptococcus pneumonia’s, S.aureus, Neisseria meningitis, Haemophilus influenza and moraxella catarrhalis
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20
Q

what characterizes the flora of the lower respiratory tract?

A
  • generally sterile (larynx, trachea, bronchioles and lower airways
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21
Q

which colonization might occur?

A

transient colonization of upper airways

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22
Q

which bacteria can cause acute disease?

A

more virulent bacteria from upper respiratory tract

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23
Q

What could be caused by chronic aspiration?

A

polymicrobial disease

- anaerobes are predominant pathogens (peptostreptococcus)

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24
Q

how many species are found in the flora of the mouth?

A

700

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25
Q

which bacteria are predominant in the mouth? are they culturable?

A

streptococci and gram - anaerobic rods

- most of them uncultureable

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26
Q

what m.o.s are found in the esophagus?

A

oropharyngeal and yeast like fungi, bacteria from stomach

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27
Q

Which are the most common infections in the esophagus?

A
  • candida spp. and viruses like, herpes simplex virus and cytomegalovirus
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28
Q

name the most common m.o.s found in the flora of the stomach?

A
  • small numbers of acid-tolerant bacteria such as lactic acid producing bacteria (lactobacillus and streptococcus spp.) and heliobacter pylori
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29
Q

Which bacterium can cause gastritis and ulcerative disease?

A

H. pylori

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30
Q

What type of bacteria are mostly in the small intestine?

A
  • most of the bacteria are anaerobes such as peptostreptococcus, porphyromonas and prevotella
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31
Q

Causes of gastroenteritis?

A

e. g. Salmonelle and campylobacter spp.

- in small numbers as asymptomatic residents

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32
Q

What colonizes the large intestine in large numbers?

A
  • various different bacteria and yeast like fungi
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33
Q

Most common bacteria of the large intestine are?

A

Bifidobacterium, Eubacterium, Bacteroides, Enterococcus, and the Enterobacteriaceae family

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34
Q

What are the most common causative agents of intraabdominal disease?

A
  • Escherichia coli and Bacteroides fragilis = minor members of the intestinal flora
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35
Q

What are the most common bacteria in the large intestine but rarely responsible for disease?

A

eubacterium and bifidobacteriumm

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36
Q

name the causes of antibiotic treatment to the flora of the l.i.

A

can rapidly alter the population, causing the proliferation of antibiotic-resistant microorganisms, such as Enterococcus, Pseudomonas, and yeast-like fungi

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37
Q

What are the anatomic areas of the genitourinary system which are permanently colonized with m.o.s?

A

anterior urethra and vagina

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38
Q

What are the most numerous m.o.s in the anterior urethra?

A

lactobacilli, streptococci, and coagulase-negative staphylococci the most numerous → relat. avirulent

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39
Q

Which organisms can also colonize the urethra transiently?

A

fecal organisms like Enterococcus, Enterobacteriaceae, and Candida

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40
Q

Which pathogens are common causes of urethritis and can persist as asymptomatic colonizers of the urethra?

A

N.gonorrhoae and C.trachomatis

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41
Q

Which bacteria are present in the vaginal flora of newborn girls and how long do they stay?

A

lactobacilli at birth

predominate for 6 weeks

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42
Q

How does the vaginal flora change?

A

to include staphylococci, streptococci and enterobacteriaceae

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43
Q

How and when does the v. flora change again?

A
  • estrogen in the puberty

- lactobacilli become preoominant again

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44
Q

What are important causes of vaginitis?

A

N. gonorrhoeae, Trichomonas vaginalis,

C. albicans and Candida glabrata

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45
Q

What are causes of persistent infections?

A

herpes simplex virus and papillomavirus

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46
Q

What colonizes the cervix?

A
  • not normally colonized
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47
Q

What bacteria can cause cervicitis?

A

N. gonorrhoeae and C.trachomatis

actinomyces can also produce disease

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48
Q

The persistent air microbial flora contains?

A
  • micrococci (e.g. micrococcus flavus), sarcina spp. (e.g. sarcina alba) and fungal spores
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49
Q

What is the transient air microbial flora?

A

microorganisms that are accidentally getting in the air by sneezing, coughing, talking and laughing in the form of droplets
- can be pathogenic

50
Q

how can the pollution of the indoor air be evaluated?

A

by counting the total number of colony-forming units (CFU) in 1m3 of air

51
Q

Which m.os are persistent in the microbial flora of water?

A

specific aquatic aerobic microorganisms like Pseudomonas fluorescens, Micrococcus roseus

52
Q

Which type of bacteria are rarely found in the water?

A
  • anaerobic
53
Q

transient water m. flora contains?

A

consists of the microorganisms that are accidentally getting in the water with faeces and urine.

54
Q

Examples of transient water m. flora bacteria

A

very pathogenic microorganisms like, for instance, salmonellae of enteric fever, shigellae, leptospirae and Vibrio cholerae

55
Q

How can the m. pollution of water be evaluated?

A

by counting the total number of colony-forming units (CFU) in 1 mL of the water

56
Q

How does soil promote the growth of m.o.s?

A

rich in nutrients

57
Q

What includes the persistent soil microbial flora?

A

nitrogen-fixing, denitrifying, cellulose-splitting and sulfur bacteria, pigmented bacteria, fungi and protozoa

58
Q

What includes the transient soil microbial flora?

A

microorganisms that are accidentally getting in the soil with faeces and urine (e.g., enterococci, Clostridium perfringens)

59
Q

What type of spores can be found in the soil?

A

spores of clostridia causing tetanus, anaerobic infections and botulism

60
Q

How can the m.f. of soil be evaluated?

A

by counting the number of colony-forming units (CFU) in 1 g of the soil

61
Q

What is a symbiosis?

A

biological relationship between humans and microorganisms

62
Q

name the types of harmless symbiosis

A
  • Mutualism
  • Commensalism
  • Metabiosis
  • Satellitism
63
Q

name the types of antagonistic symbiosis

A
  • Antibiosis
  • Competition
  • Predation
  • Parasitism
64
Q

What is mutualism?

A

relationship between individuals where both individuals benefit

65
Q

What is commensalism?

A
  • 2 living organisms

- one benefits and the other is not significantly harmed or helped

66
Q

What type of symbiosis is the human microbial flora?

A

commensalim

67
Q

What is metabiosis?

A
  • one microorganism creates or prepares a suitable environment for the second
  • e.g., bacteria decompose proteins to ammonia that is further oxidized to nitrous acid by the denitrifying bacteria
68
Q

What is satellitism?

A

bacteria in which certain bacterial species grow more vigorously in the immediate vicinity of colonies of other unrelated species, owing to the production of an essential metabolite by the latter species
- e.g. Staphylococcus aureus growing on the blood agar provides some factors for the growth of Haemophilus influenzae)

69
Q

What is antibiosis?

A
  • antagonistic relationship between two or more microorganisms → detrimental to at least one of them or an antagonistic relationship between a microorganism and the metabolic substances produced by another
  • e.g., the fungi of Penicillium genus produce penicillin, which is toxic to bacteria
70
Q

What is competition?

A
  • antagonistic relationship where better adapted to environment microorganisms utilize nutrients not leaving them to others
  • e.g., pathogenic enterobacteria cannot survive long enough in the water due to the persistent microbial flora of the water).
71
Q

Define predation

A
  • antagonistic relationship where m.o.s eat other m.o.s

- human intestinal amoeba eat enteric bacteria

72
Q

Define parasitism

A
  • one individual, the parasite, benefits at the expense of the other, the host
  • (e.g., relationship between strict pathogenic microorganisms and human; relationship between virulent bacteriophages and bacteria)
73
Q

Which physical factors affect m.o.s?

A
  • pH
  • temperature
  • radiation
  • ultrasonic waves
  • pressure: hydrostatic, osmotic
74
Q

What does the pH define?

A
  • physicochemical parameter showing acidity or alkalinity of the solution
  • negative logarithm of hydrogen ion concentration in the solution
75
Q

changes in the pH can lead to?

A
  • denaturing of enzymes and other proteins

- interfere with pumping of ions at the cell membrane

76
Q

what are acidophiles?

A

the bacteria which grow best at a pH of 1.0 to 5.4 (e.g., lactobacilli);

77
Q

What are neutrophils?

A

the bacteria which exist from pH 5.4 to 8.0 (e.g., most of the bacteria that cause disease in humans);

78
Q

What are alkaliphiles?

A

the bacteria which tolerate pH in the range of 8.0 to 11.5 (e.g., Vibrio cholerae)

79
Q

How does high temperature affect m.o.s?

A

denaturation of all proteins incl. enzymes

80
Q

How does low temperature affect m.o.s?

A

slows down metabolic reactions of microorgs to a critical limit

81
Q

what are psychrophiles?

A

the bacteria which grow best at temperatures of 15 to 20 °C (e.g., Bacillus globisporus)

82
Q

what are mezophiles?

A

the bacteria which grow best at temperatures between 25 and 40 °C (e.g., bacteria pathogenic for humans)

83
Q

what are thermophiles?

A

the bacteria which grow best at temperatures from 50 to 60 °C (e.g., bacteria found in compost heaps)

84
Q

How long are the wavelengths of UV light?

A
  • electromagnetic waves range from 40 to 390 nm
85
Q

What are the most effective UV wavelengths in killing m.o.s?

A
  • range from 200-254nm
86
Q

How do UV waves kill m.o.s?

A

cause denaturation of proteins and damage of nucleic acids

87
Q

How does ionizing radiation affect m.o.s?

A

damages nucleic acids and produces peroxides → act as powerful oxidizing agents in cells

88
Q

How long are X-ray waves?

A
  • 0.1-40nm
89
Q

What are gamma rays?

A

have a shorter wavelength

90
Q

How much millirad of radiation kills bacteria?

A

0.3-0.4 millirads

91
Q

What type of waves contains microwave radiation? and how long are they?

A
  • electromagnetic waves → wavelengths in the

range of 1 mm to 1 m

92
Q

What is the effect of microwaves?

A

water molecules absorb energy of the microwaves and release heat to surroundings

93
Q

What waves has strong visible light and how long are they?

A

electromagnetic waves → wavelengths from 400 to 700 nm (violet to red light)

94
Q

What effect does visible light have?

A
  • can have direct bactericidal effects by oxidizing light sensitive molecules such as riboflavin and porphyrins in bacteria
95
Q

How high are the frequencies of ultrasonic waves?

A

higher than 20kHz

96
Q

What is caused by ultrasonic waves?

A

cause cavitation effect – the formation of a partial vacuum in the fluid cytoplasm of bacterial cell
- The bacteria exposed to ultrasonic waves disintegrate, and their proteins are denatured

97
Q

Define hydrostatic pressure on m.o.s

A
  • pressure exerted by standing water, in proportion to its depth
98
Q

What happens if bacteria which live at high hydrostatic pressures leave their environment?

A

die if left in the laboratory for only a few hours at standard atmospheric pressure

99
Q

How are bacteria called who live in these hydrostatic pressure environments?

A

barophiles

100
Q

define osmotic pressure

A

= pressure required to prevent the net flow of water by osmosis

101
Q

The osmotic pressure of a solution is…

A

proportional to the number of particles dissolved in a given volume of that solution (e.g., amount of NaCl)

102
Q

What leads to hyper osmotic conditions?

A

high concentration of salts in a solution

103
Q

What is caused by hyperosmotic conditions?

A
  • water moves out from microbial cells causing plasmolysis -> death of cells
104
Q

What is the effect of acids? where are they used?

A
  • lower pH and denature proteins (e.g. benzoic acid, citric acid)
  • are used in food preservation
105
Q

what is the effect of alkalis? where are they used?

A
  • raise pH
  • denature proteins
  • found in soaps
106
Q

effect and location of heavy metals

A
  • denature proteins (e.g.silver nitrate)

- used in disinfection and antisepsis

107
Q

effect and location of halogens

A
  • oxidize cell components in absence of organic matter (e.g. chloridine, iodine)
  • used in desinfection and antisepsis
108
Q

effect of alcohols and their location

A
  • dissolve lipids of cell membrane and denature proteins (e.g. ethyl alcohol, isopropyl alcohol)
  • used in disinfection and antisepsis
109
Q

effect and location of oxidizing agents

A
  • disrupt disulfide bonds in proteins (e.g. hydrogen peroxide)
  • used in desinfection and antisepsis
110
Q

effect and location of phenols

A
  • disrupt membranes, denature proteins and inactivate enzymes;
  • not impaired by organic matter (e.g., phenol, triclosan)
  • They are used in disinfection and antisepsis
111
Q

effect and location of alkylating agents (aldehydes)

A
  • disrupt structure of proteins and nucleic acids (e.g., formaldehyde, glutaraldehyde)
  • used in disinfection
112
Q

effect and location of quaternary ammonium compounds

A
  • dissolve lipids
  • disrupt cell membranes and inactivate enzymes (e.g., benzalkonium chloride, cetylpyridinium chloride)
  • used in antisepsis
113
Q

effect and location of dyes

A
  • interfere with replication due to the damage of DNA, or block cell wall synthesis (e.g., acridine dyes)
  • used in antisepsis
114
Q

Which chemical factors are only used in antisepsis?

A
  • dyes

- quarternary ammonium compouns

115
Q

Which chemical factors are used in both disinfection and antisepsis?

A
  • heavy metals
  • halogens
  • alcohols
  • oxidizing agents
  • phenols
116
Q

what are natural antibiotics? name examples

A
  • biologically active substances produced by certain species of fungi (molds) with toxic effect against bacteria
  • (e.g., penicillin G and V naturally produced by Penicillium spp.; cephalosporin C naturally produced by Cephalosporium spp.)
117
Q

what are bacteriocins?

A
  • proteinaceous or peptidic toxins naturally produced by bacteria
118
Q

What is the function of proteinaceous or peptidic toxins?

A

inhibit the growth of similar or closely related bacterial strain(s) (e.g., colicins produced E. coli bacteria.

119
Q

what are phytoncides?

A

volatile organic compounds derived and produced from plants

120
Q

function of phytoncides?

A

protect themselves from microorganisms (e.g., phenolic acids found in branches and needles of the spruces and pines)

121
Q

what are bacteriophages?

A
  • are viruses infecting, replicating and causing lysis of bacterial cells

Microbiology pt.1 (10 decks)

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