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TERM 3- Premidterm > L3, L5, L7- Microbiome and Biology of Gram +/- Bacteria > Flashcards

L3, L5, L7- Microbiome and Biology of Gram +/- Bacteria Flashcards

1
Q

___________ bacteria are commonly ubiquitous on the skin

A

Staphylococcus

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2
Q

microbiota are also known as….

A

commensal flora

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3
Q

very high numbers of bacteria are found in the mouth and large intestine, especially…

A

Escherichia coli

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4
Q

microbiota are importantly absent in (1) or (2) locations (include examples)

A

1- non-epithelial
2- mucosal
ex. blood, CSF

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5
Q

_______ is a common opportunistic gut infection that follows from the death of numerous gut flora due to antibiotic use

A

C. diff (clostridium difficile)

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6
Q

list 4 general characteristics of microbiome

A
  • protection against disease
  • important for barrier and immune modulation
  • influences host metabolism and drug interaction
  • possible source of infection (endogenous E.coli in Colon)
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7
Q

define dysbiosis and its effects

A

this is usually a transient effect resulting from long-term or repeated antibiotic use leading to the loss of beneficial species, altering microbiota

associated with chronic diseases like Crohn’s or IBS

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8
Q

describe prokaryotic DNA

A

circular, ~1 mil. BPs + many Plasmids with ~50k BPs

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9
Q

breakdown prokaryotic vs eukaryotic ribosomes

A

Pro: 30S + 50S = 70S
Euk: 40S + 60S = 80S

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10
Q

plasmids in bacteria contain DNA coding for….

A
  • antibiotic resistance
  • toxins
  • mobile gene transfer
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11
Q

list in order the stages of bacterial growth

A

1) lag phase
2) log / exponential phase
3) stationary phase
4) death phase

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12
Q

describe the features of Lag phase

A
  • newly inoculated cells, adjust to environment (is there food, space, etc)
  • cells not multiplying at maximum rate
  • population is sparse or dilute
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13
Q

describe the features of Log or exponential phase

A
  • growth occurs at exponential rate and cells are at maximal rate of cell division
  • continues as long as environment is favorable (nutrients present, etc)
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14
Q

describe features of stationary phase

A
  • population at maximum number
  • rate of cell inhibition/death = rate of cell multiplication
  • accumulation of toxic waste products
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15
Q

describe features of death phase

A
  • decline in growth rate
  • caused by depletion in nutrients, O2
  • excretion of toxic waste products
  • increased density of cells (limited space)
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16
Q

describe how and why bacteria obtain Fe

A
  • Fe is required for cytochromes

- most Fe is sequestered in Hb, therefore bacteria must have mechanisms to extract Fe from Hb

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17
Q

list the three ways bacteria generate ATP

A
  • aerobic respiration
  • anaerobic respiration
  • fermentation
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18
Q

_______ levels are usually measured in urine samples to serve as an indicator of infection since the humans cannot break it down

A

nitrates (E.coli can convert it to nitrites)

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19
Q

if bacteria deplete enough O2 during an infection, the anoxic conditions can lead to….

A
  • host tissue damage
  • immune cells work poorly
  • antimicrobials are less effective
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20
Q

most pathogens have an optimal temperature of growth at (1) and are referred to as (2)

A

1- 37C

2- mesophiles

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21
Q

define obligate aerobe

A

O2 necessary, only aerobic respiration is used (die w/o O2)

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22
Q

define obligate anaerobe

A

can’t use O2 and die in its presence

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23
Q

define facultative anaerobe

A

uses both aerobic and anaerobic respiration, although thrive more in aerobic conditions

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24
Q

define microaerophiles

A

require lesser amounts of O2 (5-10%)

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25
Q

mycobacterium tuberculosis is considered a (obligate aerobe / obligate anaerobe / facultative anaerobe / microaerophile)

A

obligate aerobe

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26
Q

clostridium difficile and other clostridiums are considered a (obligate aerobe / obligate anaerobe / facultative anaerobe / microaerophile)

A

obligate anaerobes

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27
Q

E.coli is considered a (obligate aerobe / obligate anaerobe / facultative anaerobe / microaerophile)

A

facultative anaerobe

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28
Q

most human pathogens are considered a (obligate aerobe / obligate anaerobe / facultative anaerobe / microaerophile)

A

facultative anaerobe

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29
Q

Helicobacter pylori is considered a (obligate aerobe / obligate anaerobe / facultative anaerobe / microaerophile)

A

microaerophile

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30
Q

describe where obligate aerobes, obligate anaerobes, and facultative anaerobes are found in sample vials

A
  • Ob. Aero.- at top near cap (O2 needed)
  • Ob. Anaero.- at bottom, furthest from cap (no O2)
  • Fac. Anaero- throughout vial, although most near cap
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31
Q

superoxide dismutase reaction

A

2O2- + 2H+ —> H2O2 + O2

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32
Q

catalase reaction

A

2H2O2 —> 2H2O + O2

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33
Q

aerobic bacteria must have one or both of these enzymes to survive the ROS produced from cellular respiration

A
  • superoxide dismutase (O2 radicals)

- catalase (H2O2)

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34
Q

by adding (1) to clinical samples, catalase can serve as a basis for the classification of (2)

A

1- H2O2
2- Staphylococcus
(Cat +)

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35
Q

most human pathogen live at pH between 6-8 and are termed (1), otherwise they may be (2) or (3)

A

1- neutrophiles
2- acidophiles (obligate acidophiles)
3- alkalinophiles

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36
Q

two common acidophiles found in the body are….

A

1) Lactobacillus (GI infection, vaginal canal to maintain acidic environment)
2) H. Pylori (GI infection)

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37
Q

‘picky’ bacteria or ones that require a special, or (1), media are called (2)

A

1- defined media

2- fastidious

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38
Q

samples for cultures that are taken from easy to access areas in the body have (a lot/little/no) endogenous microbes and require a (2) media

A

1- a lot

2- selective media

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39
Q

samples for cultures that are taken from difficult to access areas in the body have (a lot/little/no) endogenous microbes and require a (2) media

A

1- little (lungs) to none (CSF)

2- rich media

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40
Q

describe MacConkey Agar

A
  • selective and differential media for fecal samples
  • allows for growth of E.coli and Salmonella
  • lactose is present: E.Coli will react and turn it pink, Salmonella doesn’t react => no color change
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41
Q

describe Blood Agar

A
  • selective, rich media (with 5% sheep’s blood)

- α, β, γ- hemollysis determined

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42
Q

describe α-hemolysis of Blood Agar

A
  • lysis of RBCs, incomplete breakdown of Hb

- appears greenish/tan around the colony

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43
Q

describe β-hemolysis of Blood Agar

A
  • complete lysis of RBCs and breakdown of Hb
  • clear zone around each colony
  • indicates Staph. aureus
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44
Q

describe γ-hemolysis of Blood Agar

A

no hemolysis, appears as faint clear area

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45
Q

describe Chocolate Agar

A

heated Blood Agar

46
Q

describe Nutrient Agar

A

rich media for non-fastidious bacteria

47
Q

describe the agar required for Mycobacterium Tuberculosis

A

Lowenstein-Jensen Agar- rich in lipids and O2

-takes weeks to grow in BSL-3

48
Q

describe the agar required for Neisseria Gonorrhea

A

Thayer-Martin Agar: Chocolate Agar (heated Blood Agar) with antibiotic added (selective) to restrict growth of usual flora (cervical or urethral)

49
Q

describe media needed for throat swabs and what is usually trying to be determined

A
  • selective media due to presence of numerous endogenous microbes (commensal flora)
  • usually to Dx Streptococcus infections
50
Q

describe media needed for sputum samples (include best method for obtaining)

A
  • rich media due to very few commensal flora (endogenous microbes)
  • best obtained through bronchial/trans-tracheal aspiration rather than cough
51
Q

define bacteremia

A
  • presence of bacteria in blood (symptomatic or asymptomatic)
  • may indicate deeper infection like meningitis
52
Q

define septicemia

A

serious immunological hypersensitivity response to bacteria, viruses, or fungi

53
Q

infection/inflammation of CNS membranes is termed (1), of the brain tissue is termed (2), and of both is termed (3)

A

1- meningitis
2- encephalitis
3- meningoencephalitis

54
Q

MRSA = …

A

methicillin resistant Staphylococcus aureus

55
Q

fecal specimens are usually put into _________ agar

A

MacConkey Agar- promotes E.Coli and Salmonella growth

56
Q

list some of the possible states opportunistic bacteria take advantage of

A
  • weakened immune system
  • altered microbiota (GI, vaginal)
  • breach of integumentary barrier
57
Q

define virulence

A

pathogen’s ability to infect or damage host (what mechanism or tools does it have)

58
Q

list the four outcomes of a microbial host interaction

A
  • communalization
  • colonization
  • disease
  • latency
59
Q

list some host factors that influence the outcome of an infection

A

age, EtOH use, coexisting disease, portal of entry, preexisting trauma, gender, immune status, malnutrition

60
Q

list some pathogenic factors that influence the outcome of an infection

A
  • antibiotic resistance
  • duration of exposure
  • infection dose
  • virulence factors
61
Q

most infections have an acute infection followed by (1) or (2) [describe each]

A

1- persistent infection: slow, long-term growth of microbe

2- latent infection: repeated acute infections with dormant periods in between (i.e. HSV(

62
Q

list some microbial factors that lead to clinical signs and symptoms observed in a patient

A
  • ability to grow in numbers at specific location
  • damaging products: enzymes, toxins, cellular components
  • ability to sense/respond to host counter measures
63
Q

list some host factors that lead to clinical signs and symptoms observed in a patient

A

cytokines, interleukins, respiratory bursts

64
Q

describe the features of an exotoxin

A
  • released by pathogen (works at distant sites)
  • heat stable (usually)
  • highly specific
  • very toxic
65
Q

describe the features of an endotoxin

A
  • part of pathogen’s structure
  • heat stable
  • low specificity
  • low toxicity
66
Q

define the 3 classes of exotoxins/endotoxins

A
  • Class I: binds to cell surface –> triggers intracellular response
  • Class II: binds to cell membrane, causes membrane damage
  • Class III: enters cell
67
Q

list the bacterial enzymes that contribute to virulence

A
  • catalase
  • urease- breaksdown Urea
  • IgA protease- breaksdown IgA
  • Neuraminidase- cleaves neuraminidase
  • Coagulase
68
Q

describe function and effect of coagulase in a pathogen

A

convert fibrin to fibrinogen –> fibrinogen wraps around microbe for protection (from immune cells)

69
Q

list the steps of an infectious disease process

A

1) exposure and entry
2) adhesion and colonization
3) invasion and multiplication
4) spread and dissemination

70
Q

describe the two types of adhesion from bacteria

A

Nonspecific = reversible: hydrophobic interactions, electrostatic attraction, biofilm attachment

Specific = irreversible: specific bonds between pathogen and host cells

71
Q

the availability of micro-/macro- nutrients for pathogens allows the following evasive enzymes to be produced for the invasion/multiplication and spread/dissemination in other parts of the body

A
  • hyaluronidases
  • proteinases
  • nucleases
  • lipases
72
Q

Fe uptake into bacteria is completed via….

A

sidophores- cell membrane structures allowing for the binding and influx of Fe

73
Q

list three methods pathogens use to evade host defenses

A
  • capsules
  • antigenic variance (changes rapidly)
  • host mimicry (host like antigens)
74
Q

some bacteria have enzymes that convert plasminogen to plasmin for….

A

breaking down blood clots –> spread and dissemination of bacterial infection

75
Q

attachment of bacteria contributes to pathogenicity by….

A

preventing removal

76
Q

these 4 factors help bacteria evade immune system and contributes to its pathogenicity

A
  • secreted toxins
  • antigenic variation
  • biofilm formation
  • exotoxins
77
Q

urine specimens are added to agar plates via….

A

calibrated loop, transfers ~0.01-0.001 mL

78
Q

estimating the number of viable bacteria present from a specimen on a plate is through….

A

(colony count) Colony Forming Units, ~1000 bacteria

79
Q

describe the results of a urine culture and what it indicates (hint 4 results)

A

Negative: no growth after 16-24 hrs OR 2 or more types of urogenital flora isolated (<10000 CFU/mL)

Positive: >100000 CFU/mL isolated

Depends: single type of urogenital flora isolated (<10000 CFU/mL)

80
Q

bacterial quantification can be determined through _______, which record optical density / absorbance

A

spectrophotometer

Note- inaccurate in lag and death phases for viable cells

81
Q

describe the benefits of live count serial dilutions

A
  • more accurate than loop calibrated loop at high and low concentrations
  • important for testing growth rate curves
  • good for testing if a drug is working or not (tests for quantity, not just for presence)
82
Q

describe the process of live count serial dilutions

A
  • created a series of diluted samples (in 1:9 ratios)
  • spread or pour each onto growth media
  • count the CFUs of the plate with 30-300 colonies
  • determine [bacteria] in original sample via dilution calculation
83
Q

Staphylococcus are Gram (+/-)

A

gram +

84
Q

Escherichia Coli are Gram (+/-)

A

gram -

85
Q

describe the process of a gram stain and the two possible results

A

1) heat fix bacteria onto glass slide
2) stain with Purple Crystal Violet
3) de-stain with alcohol
4) counter-stain with Pink Safranin

Purple = Gram +
Pink = Gram -
86
Q

the two predominate bacterial shapes are….

A
  • Coccus sphere
  • Bacillus rod

(then there is spirochete or atypical shaped)

87
Q

cell wall of bacteria is made of….

A

peptidoglycan

88
Q

list the optional features of bacterial cell structure that can enhance or determine its ability to cause disease

A
  • Capsule

- Appendages: Flagella, Pili

89
Q

list layers of Gram+ bacteria

A
  • thick peptidoglycan layer

- plasma membrane

90
Q

list layers of Gram- bacteria

A
  • outer membrane
  • thin peptidoglycan layer
  • periplasmic space
  • plasma membrane
91
Q

Gram(+/-) are more resilient and can survive without moisture, therefore they can be found on (2). Gram(+/-) die quickly is dry areas and are mostly found in (4).

A

1- Gram+
2- skin

3- Gram-
4- GI tract, Urogenital tract

92
Q

Peptidoglycan is made of repeating (1) and (2) units, cross-linked by (3) long AA bridge via (4) enzyme

A

1- NAG (N-acetyl glucosamine)
2- NAM (N-acetyl muramic acid)
3- tetrapeptide (cleaved from pentapeptide via (4))
4- transpeptidase or Penicillin Binding Proteins (PBPs)

93
Q

in Gram+ bacteria, peptidoglycan layer is about (1) layers thick, and has (2) and (3) molecules serving as scaffold with (4) as the only difference

A

1- 4-10 layers
2- Teichoic acid
3- LipoTeichoic acid
4- Lipotechoic acid is connected to lipid on plasma membrane, techoic acid has no such connection

94
Q

the outer membrane of Gram- bacteria is primarily made of (1) with the following three subunits: (2)

A

1- LPS (LipoPolySaccharide)

2- Lipid A, core polysaccaride, O antigen (variable unite)

95
Q

_____ part of LPS in Gram- bacteria has a toxic effect and is recognized by immune cells

A

Lipid A

96
Q

LPS also functions as an Endotoxin, causing….

A

inflammation –> sepsis

97
Q

what happens in the periplasmic space in Gram- bacteria

A

respiration / fermentation

98
Q

______ are trans-lipid and modulate cell transport, especially antimicrobials (out of cell)

A

Porins

99
Q

a bacterial cell capsule is made of (1) and functions to (2); note if it is thin and not well organized it is termed (3)

A

1- glycocalyx (gelatinous sugar material)
2- help organism resist environmental and immunlogical conditions
3- Slime layer

100
Q

encapsulated bacteria are termed (1) since they aren’t recognized by WBCs and are a major virulence factor for dissemination, particularly in (2) patients

A

1- anti-phagocytic (non-encapsulated are easily phagocytosed by macrophages / neutrophils)
2- asplenic

101
Q

describe the two types (or 2.5 types) of adhesins found on bacteria

A

(function in attachment role)

  • Fimbriae: numerous, short
  • Pili: few, long, usually has specific host receptor
  • Sex Pili are involved in gene transfer
102
Q

describe the aspects / functions of flagella in bacteria

A
  • based in cell wall –> extends extracellular (can be multiple, and on one or more sides)
  • function is motility –> contributes to virulence (ex. penetrates mucus layer)
  • recognized by innate immune system
  • present in Salmonella, E.Coli; absent in Shigella
103
Q

______ is found based in cell wall of Gram- bacteria and acts as needles to inject effector proteins into host cell (contributes to virulence –> alters host cell characteristics)

A

T3SS, type 3 secretion system

104
Q

name two important Endospores

A
  • Bacillus

- Clostridium

105
Q

describe an endospore

A
  • highly resistant form of bacteria due to a harsh environment
  • usually/often found in soil
  • germinates into vegetative bacteria once in suitable environment
  • if spores gain access to inner tissues –> serious infections / disease
106
Q

Staphylococcus aureus is a Gram (+/-) (cocci/bacillus)

A

Gram+ cocci

107
Q

serial dilution calculation formula

A

number of CFUs (original sample) = CFUs measured / (mL * dilution)

-note keep everything in 10^ form

108
Q

what is a key function of lack of cell wall feature for Mycoplasmas

A

allows it to withstand osmotic pressure (thick cervicitis)

109
Q

lactobacillus is a (large/small) Gram (+/-) (cocci/bacillus)

A

large Gram+ bacillus (rod)

110
Q

Mycobacterium species are recognized through…..

A
  • neither Gram +/- stain

- positive Acid-Fast stain

111
Q

Mycoplasma are recognized through…..

A
  • neither Gram +/- stain

- no cell wall

112
Q

Chlamydia species are recognized through…..

A
  • neither Gram +/- stain

- positive Giemsa stain

TERM 3- Premidterm (20 decks)

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