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NBDE 1 > Day 4.2.1 > Flashcards

Day 4.2.1 Flashcards

1
Q

What is the first step in the replicative cycle of viruses?

A

attachment through a receptor

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2
Q

what are the specific receptors for hiv

A

cd4 on t cells

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3
Q

what are the specific receptors for rhinoviruses

A

ICAM on upper respiratory epithelial cells

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4
Q

what are the specific receptors for polio virus

A

immunoglobulin-like receptors

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5
Q

how do viruses enter a cell

A

after binding to specific recpetors - 2 methods -

receptor mediated endocytosis

membrane fusion

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6
Q

what method does influenza virus enter a cell with

A

receptor mediated endocytosis

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7
Q

what method do paramyxoviruses enter cells with

A

membrane fusion

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8
Q

name two viruses that enter cells through membrane fusion

A

herpesviruses

paramyxoviruses

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9
Q

name two viruses that enter a cell by receptor mediated endocytosis

A

influenza

adenovirus

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10
Q

how is uncoating of viruses triggered

A

by pH changes in endosomes

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11
Q

name a virus that undergoes uncoating due to pH changes

A

influenza A virus

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12
Q

name the processes by which viruses replicate and produce viral protein

A

transcription

translation

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13
Q

where do all dna viruses replicate

A

nucleus

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14
Q

what is the exception in dna viruses wrt site of replication

A

poxviruses (cytoplasm)

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15
Q

what enzyme do dna viruses use to replicate

A

host cell rna polymerase

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16
Q

where do all rna viruses replicate

A

in the cytoplasm of host cell

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17
Q

what enzyme do rna viruses use to replicate

A

own rna polymerase

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18
Q

what are the exceptions wrt site of replication in rna viruses

A

retroviruses

orthomyxoviruses

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19
Q

what are the steps in replicative cycle of viruses

A 
attachment
entry
uncoating
replication and viral protein production
asssembly
release
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20
Q

how are replicated viruses released from host cell?

A

2 methods

  • budding
  • host plasma membrane rupture
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21
Q

phases of one step growth analysis

A
  1. adsorption of virus
  2. eclipse phase
  3. synthetic phase
  4. latent period
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22
Q

how long does eclipse phase last

A

10-12 hours

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23
Q

what does the eclipse phase correspond to

A

the period during which the input virus becomes uncoated

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24
Q

what is the peculiar feature of the eclipse phase

A

no infectious virus can be detected during this time because it is undergoing uncoating

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25
Q

when does the synthetic phase start

A

around 12 hours post-infection

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26
Q

what does synthetic phase correspond to

A

the time during which new virus particles are assembled

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27
Q

during what period can no extracellular virus be detected?

A

latent period

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28
Q

what characteristics do orthomyxoviruses and paramyxoviruses share

A

spherical shape
single stranded rna
hemagglutinin
negative sense rna

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29
Q

what is the cytopathic effect of paramyxoviruses

A

syncytia formation

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30
Q

What virus doesn’t cross placenta?

A

measles

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31
Q

list viruses that cross placenta

A

rubella
herpes
hiv
cmv

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32
Q

viruses that cause respi disease in children

A

respiratory syncytial virus
parainfluenza viruses 1-4
rhinoviruses
adenoviruses

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33
Q

common viral causes of pharyngitis

A

coxsackievirus a
adenoviruses
orthomyxoviruses (influenza viruses)
EBV

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34
Q

common causes of viral gastroenteritis

A

rotavirus
noroviruses
sapoviruses
adenoviruses and astroviruses

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35
Q

what is the most common cause of viral gastroenteritis in children

A

rotavirus

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36
Q

noroviruses aka

A

norwalk virus

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37
Q

common cause of viral gastroenteritis in adults

A

adenoviruses and astroviruses

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38
Q

viruses that cause common cold

A

rhinoviruses
coronaviruses
adenoviruses
coxsackieviruses

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39
Q

most common pediatric viral diseases with a rash

A 
measles
rubella
roseola (hhv 6)
erythema infectiosum
vzv
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40
Q

most common causes of aseptic meningitis

A

coxsackievirus
echoviruses
mumps viruses

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41
Q

what are the only dsRNA viruses

A

reoviruses

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42
Q

what are the most common cause of infectious diarrhea in infants and young children

A

rotaviruses

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43
Q

most common human disease caused by an arbovirus

A

dengue fever

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44
Q

most common cause of epidemic encephalitis

A

Japanese encephalitis virus

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45
Q

most common viral cause of mental retardation in US

A

cmv

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46
Q

which family comprises the genera rubiviruses and alphaviruses?

A

togaviruses

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47
Q

example of rubiviruses

A

rubella virus

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48
Q

example of alphavirus

A

arthropod borne viruses

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49
Q

how is rubella virus different from other togaviruses?

A

respiratory virus

does not cause readily detectable cytopathologic effects

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50
Q

five classic childhood exanthems

A 
rubella
measles
roseola
fifth disease
chickenpox
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51
Q

typical picture of rubella

A

maculopapular rash that appears first on face and neck then quickly spreads to trunk and upper extremities then to legs

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52
Q

what disease shows first distinct then flushed appearance of lesions

A

rubella

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53
Q

what is the onset of rash accompanied by in rubella

A

low grade fever

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54
Q

how long does the rash in rubella last

A

3-5 days

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55
Q

rubella aka

A

3 day measles

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56
Q

how long does fever persist

A

not more than 24 hours

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57
Q

most prominent and characteristic symptom of rubella

A

lymphadenopathy of postauricular, occipital and posterior cervical lymph nodes

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58
Q

can lymphadenopathy in rubella occur in absence of rash

A

yes

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59
Q

what can be the effects of rubella infection during pregnancy

A

stillbirth
spontaneous abortion
congenital rubella syndrome

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60
Q

congenital rubella syndrome classical triad

A

cataracts
heart defects
deafness

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61
Q

how is staph aureus different from other staph

A

coagulase positive

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62
Q

how does s aureus infection begin

A

by traumatic inoculation of organism

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63
Q

what kinds of skin lesions do s aureus cause

A

boils
carbuncles
impetigo
scalded skin syndrome

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64
Q

what other than skin lesions do s aureus cause

A 
abscesses
sepsis
osteomyelitis
pneumonia
endocarditis
food poisoning
toxic shock syndrome
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65
Q

what kind of toxins does s aureus produce

A

cytolytic
exfoliative
enterotoxins
toxic shock syndrome toxin

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66
Q

name the cytolytic toxins produced by s aureus

A 
alpha
beta
delta
gamma
Panton-Valentine leukocidin
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67
Q

name the exfoliative toxins produced by s aureus

A

A

B

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68
Q

name the enterotoxins produced by s aureus

A

A - E, G, I.

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69
Q

superantigens

A

toxins (polypeptides) that bind to class ii MHC molecules on macrophages — interact with specific T cell receptors — massive release of cytokines by both macrophages and T cells

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70
Q

name 3 superantigens

A

Exfoliative toxin A
enterotoxins
TSST 1

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71
Q

what forms of coagulase do s aureus strains contain

A

2 - bound and free

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72
Q

function of bound coagulase

A

it is bound to the cell wall and can directly convert fibrinogen to insoluble fibrin and cause staph to clump

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73
Q

how does cell-free coagulase cause staph clumping

A

cell-free coagulase + globulin plasma factor (coagulase-reacting factor) = staphylothrombin (thrombin-like factor) —> catalyses conversion of fibrinogen to fibrin

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74
Q

how does staph clumping help staph

A

it helps them from phagocytosis

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75
Q

what other enzymes do staph produce

A

hyaluronidase
fibrinolysin
lipases
nuclease

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76
Q

hyaluronidase

A

hydrolyses hyaluronic acids

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77
Q

fibrinolysin aka

A

staphylokinase

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78
Q

what staph produce lipases

A

all s aureus strains

more than 30% coagulase negative staph

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79
Q

what is the function of lipases with staph

A

they hydrolyze lipids and ensure the survival of staph in sebaceous areas of the body

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80
Q

function of nuclease with staph

A

it is thermostable and hydrolyzes viscous dna

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81
Q

what is s aureus unable to do

A

invade through intact skin or mucous membranes

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82
Q

what does the cell wall of s aureus contain

A

ribitol phosphate teichoic acid

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83
Q

what kind of clusters do s aureus form

A

like bunches of grapes

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84
Q

what are s aureus

A

pyogenic gram positive cocci

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85
Q

predominant type of bacteria on skin

A

staph

corynebacteria

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86
Q

predominant bacteria on conjunctiva

A

sparse - gram positive cocci and gram negative rods

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87
Q

predominant bacteria on teeth

A

strep

lactobacilli

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88
Q

predominant bacteria on oral mucosa

A

strep

lactic acid bacteria

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89
Q

predominant bacteria in nares (nasal membranes(

A

staph
corynebacteria

(same as skin)

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90
Q

predominant bacteria in pharynx

A

strep
neisseria
gram negative rods
cocci

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91
Q

predominant bacteria in lower respiratory tract

A

none

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92
Q

predominant bacteria in stomach

A

H pylori

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93
Q

what % of stomach bacteria is H pylori

A

50%

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94
Q

predominant bacteria in in small intestine

A

lactics
enterics
enterococci
bifidobacteria

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95
Q

predominant bacteria in colon

A 
bacteroides
lactics
enterics
enterococci
clostridia
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96
Q

difference between colon and small intestinal dominant bacteria

A

bifidobacteria exclusive to small intestine and bacteroides and clostridia exclusive to colon

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97
Q

predominant bacteria in anterior urethra

A

sparse - staph, corynebacteria, enterics (similar to skin, and enterics)

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98
Q

predominant bacteria in vagina during child-bearing years

A

lactic acid bacteria

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99
Q

predominant bacteria in vagina during non-child-bearing years

A

mixed

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100
Q

Main pathogenic Lancefield groupings for humans

A 
A
B
C
D
G
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101
Q

what are lancefield groupings based on

A

antigenic characteristics of cell wall carb - C substance

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102
Q

common characteristics of streptococci

A 
gram positive
cocci
arranged in pairs or chains
most are facultative anaerobes
catalase negative
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103
Q

schemes used to classify strep

A

serologic properties
hemolytic patterns
biochemical properties

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104
Q

serologic classification of strep

A

Lancefield groupings:

a, b, c, d, g

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105
Q

hemolytic patterns classification of strep

A

complete (beta [b])
incomplete (alpha [a])
no hemolysis (gamma [g])

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106
Q

what strains of strep are pathogenic for humans

A

group A

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107
Q

90 % of strep disease in humans is caused by

A

group A beta hemolytic strep - S pyogenes

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108
Q

what defines the virulence of the bacteria - strep

A

M protein

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109
Q

important components in the cell wall of S pyogenes

A

M protein
lipoteichoic acid
F protein

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110
Q

Toxins produced by Group A beta hemolytic strep

A

Streptococcal pyrogenic exptoxins (Spe) A, B, C,F

DNases A to D

Streptolysins O, S

Hyaluronidase

Streptokinase A, B

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111
Q

superantigens produced by Strep pyogenes

A

SpeA
SpeB
Spe = Streptococcal pyrogenic exotoxin

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112
Q

what are SpeA and SpeB associated with

A

severe infections characterised by:

rash
hypotension
multiorgan failure
high mortality rate

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113
Q

most common organisms to cause subacute endocarditis

A

oral streptococci

why? Alpha-hemolytic

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114
Q

what strep are alpha-hemolytic (oral strep)?

A

S viridans
S mutans
S sanguis
S salivarius

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115
Q

characteristic phases of population growth in bacteria

A

A - lag
B - log
C - maximum stationary
D - decline

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116
Q

decline phase aka

A

death phase

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117
Q

log phase aka

A

exponential phase

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118
Q

what happens to bacterial cells in lag phase

A

they are metabolically active but not dividing

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119
Q

what is the cellular activity during lag phase

A

resynthesis of enzymes, coenzymes etc necessary for growth

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120
Q

what happens to bacterial cells in log phase

A

bacteria are growing and dividing at an exponential (logarithmic) rate

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121
Q

What is the period of fastest growth in the bacterial growth curve?

A

log phase

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122
Q

what is the generation time in log phase

A

maximal and constant

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123
Q

what works best in log phase?

A

cidal antibiotics

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124
Q

what is the best phase to stain bacteria culture to study them?

A

log phase

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125
Q

why does total number of viable cells remain constant in maximum stationary phase

A

medium getting depleted in nutrients and toxic quantities of waste materials lead to reduction in number of new cells produced and increase in number of dying cells

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126
Q

what kind of bacteria contain endotoxins in their outer membrane of the cell wall?

A

gram negative bacteria

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127
Q

what is the biological activity of endotoxin associated with

A

lipopolysaccharide

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128
Q

what is the toxicity of endotoxin associated with

A

lipid component

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129
Q

what is the lipid component of endotoxin

A

Lipid A

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130
Q

what is the immunogenicity of endotoxin associated with

A

polysaccharide components

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131
Q

how does lipopolysaccharide activate complement

A

by alternative (properdin) pathway

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132
Q

which one is more potent - endo or exotoxin

A

endotoxin

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133
Q

which one is more specific - endo or exotoxin

A

exotoxin

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134
Q

which one has enzymatic activity - endo or exotoxin

A

exotoxin - often

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135
Q

which one is released by organisms - endo or exotoxin

A

exotoxin

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136
Q

which one is denatured by boiling - endo or exotoxin

A

exotoxin - usually

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137
Q

which one is antigenic - endo or exotoxin

A

both

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138
Q

which one forms toxoid - endo or exotoxin

A

exotoxin

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139
Q

which one is more pyrogenic - endo or exotoxin

A

endotoxin

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140
Q

which one is part of outer membrane - endo or exotoxin

A

endotoxin

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141
Q

which one is diffusible - endo or exotoxin

A

exotoxin

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142
Q

what is the difference in structure between endo and exotoxin

A

endo is lipopolysaccharide, exo is protein

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143
Q

which one is expressed by gram positive organisms only - endo or exotoxin

A

exotoxin

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144
Q

what is essential to function of outer membrane of gram negative bacteria

A

lipopolysaccharide

145
Q

what is the function of the outer membrane of gram negative bacteria

A

to act as a protective permeability barrier

146
Q

outer membrane of gram negative bacteria permeability

A

impermeable to:

large molecules
hydrophobic compounds from the environment

147
Q

how are endotoxins released into bloodstream

A

not secreted - death of bacterial cell and breakdown of outer membrane leads to its release into bloodstream

148
Q

host responses to endotoxins

A

chills
fever
weakness
generalised aches

severe cases - shock and death

149
Q

potency of endotoxins

A

very high

150
Q

action of endotoxins in oral mucosa

A

minute amounts cause

inflammation
resorption

of adjacent bone

151
Q

effect of endotoxin on granulocytes

A

chemotactic effect on neutrophilic granulocytes - it induces phagocytosis by these cells

152
Q

what do plaque bacteria produce other than endotoxin that may initiate perio disease

A

enzymes

  • hyaluronidase
  • collagenase
  • chondroitin sulfatase
  • elastase
  • proteases
153
Q

where do you find free endotoxin

A

dental plaque

inflamed gingiva

154
Q

most likely source of bacteria in diseased perio tissue

A

subgingival plaque

155
Q

collagenase is a part of the component system of which bacteria

A

Porphyromonas spp
Clostridium spp
Bacteroides spp
Actinobacillus actinomycetemcomitans

156
Q

how is endotoxin different from most bacterial exotoxins

A

it is a LPS complex instead of a protein, composed of

  • lipid A
  • core polysaccharide
  • O antigenic side chain
157
Q

which is the portion of endotoxin most responsible for toxic activity

A

lipid A

158
Q

how does endotoxin affect complement system

A

it activates C3 in the absence of preceding activation of C1, 4, 2.

Various complement components are consumed and then their activity disappears or is reduced from serum

159
Q

detection of protein A is used as a specific identification test for

A

staph aureus

160
Q

name a major cause of nosocomial infections associated with indwelling medical devices

A

s aureus

161
Q

how does s aureus cause food poisoning

A

releasing enterotoxins

162
Q

how does s aureus cause tss?

A

release of superantigens in blood stream

163
Q

the surface of which s aureus strains are coated with protein A?

A

the strains that are not coagulase negative staph

164
Q

where is protein A bound in s aureus?

A

peptidoglycan layer or

cytoplasmic membrane

165
Q

what does protein A have a unique affinity for

A

binding to the Fc receptor of IgG and inhibiting complement fixation

166
Q

what are the important human pathogens in genus Neisseria

A

N gonorrhoeae

N meningitidis

167
Q

what is the difference in prevalence and mortality levels of N menigitidis and N gonorrhoeae

A

N gonorrhoeae infections have high prevalence and low mortality

N menigitidis have low prevalence and high mortality

168
Q

Describe salmonella

A

Gram negative
facultative
rod-shaped

169
Q

what bacterium does Salmonella share its proteobacterial family with

A

E coli - family Enterobacteriaceae - aka enteric bacteria

170
Q

what diseases does Salmonella cause in humans

A

Salmonellosis

acute gastroenteritis

171
Q

salmonellosis aka

A

enteric fever (typhoid)

172
Q

what is the cause of typhoid

A

Salmonella

173
Q

how does typhoid occur

A

it results from bacterial (salmonella) invasion of the bloodstream

174
Q

what does acute gastroenteritis result from

A

foodborne infection or intoxication

175
Q

which are the most numerous group of microbes that occur in the oral cavity

A

Streptococci

176
Q

what do streptococci cause in oral cavity

A

dental caries

177
Q

what are more serious infections than dental caries caused by strep?

A

pneumonia (s pneumoniae)
rheumatic fever (s pyogenes)
heart valve infections (s viridans)

178
Q

bacterial enzymes used clinically for removal of blood clots

A

staphylokinase
streptokinase
urokinase

179
Q

what produces staphylokinase

A

staph aureus

180
Q

what produces streptokinase

A

hemolytic streptococci

181
Q

what do staphylokinase, streptokinase and urokinase do

A

they cleave plasminogen, producing plasmin, which causes liquefaction of fibrin

182
Q

list bacteria that produce hyaluronidase

A

staph aureus
strep pyogenes
clostridium perfringens

183
Q

name 2 types of bacteria that are acid fast

A

Mycobacterium spp

Nocardia

184
Q

M tuberculosis - gram + or -?

A

neither - it doesn’t have the chemical characteristics of either

185
Q

What kind of toxins do M tuberculosis produce?

A

neither exo nor endotoxins

186
Q

are M tb motile?

A

no

187
Q

what is the shape of M tb?

A

rods

188
Q

what do M tb produce

A

niacin

189
Q

where are most mycobacteria found?

A

dry and oily locales

190
Q

what is the type of metabolism of M tb

A

obligate aerobe

191
Q

in the classic case of TB where are M tb complexes found

A

in well aerated upper lobes of the lungs

192
Q

what is the generation time of M tb

A

slow - 15 - 20 hours

193
Q

is M tb parasitic

A

yes - facultative intracellular parasite of macrophages

194
Q

what physiological characteristic of M tb contributes to its virulence

A

it slow generation time of 15-20 hours

195
Q

name a method to diagnose active TB

A

acid fast staining

196
Q

method of acid fast staining

A
  1. smear on a slide is flooded with carbol fuchsin stain
  2. decolorized with acid alcohol
  3. counterstained with methylene blue
197
Q

how do acid fast organisms react to acid fast staining

A

they resist decolorisation and appear red against blue background under microscope

198
Q

what is the acid fast property attributable to

A

presence of lipids and waxes in cell wall of certain bacteria

199
Q

what waxes do mycobacteria contain

A

mycolic acids

200
Q

name the skin test used to test for TB

A

PPD skin test

201
Q

how accurate is the ppd skin test in diagnosing TB

A

it indicates infection but not whether infection is active

202
Q

PPD = ?

A

purified protein derivative

203
Q

how is the PPD skin test done

A

a purified protein derivative extract from Mtb is injected subcutaneously and the area near injection is observed for evidence of delayed hypersensitivity reaction

204
Q

what is an indicator of tb infection in ppd test

A

delayed hypersensitivity reaction

205
Q

what does positive ppd test indicate?

A

hypersensitivity to tuberculo-proteins

206
Q

Acid fast bacteria of medical importance

A

Mtb
Mycobacterium leprae
Mycobacterium avium complex (MAC)

207
Q

What does mycobacterium avium complex consist of

A

2 species -
M avium
M intracellulare

208
Q

what does the acid fast cell wall of mycobacterium consist of?

A

peptidoglycan

glycolipids

209
Q

name a specific type of glycolipids that make up approximately 60% of the acid fast cell wall of mycobacteria

A

mycolic acids

210
Q

what is the cause of virulence of mycobacteria

A

a waxlike lipid coat

211
Q

what is the mycobacterial coat made of

A

mycolic acid
cord factor
wax D
sulfolipids

212
Q

what is mycolic acid

A

large a-branched b-hydroxy fatty acids

213
Q

what is cord factor

A

glycolipid of trehalose and two mycolic acids

214
Q

what is wax D

A

glycolipid of 15 to 20 mycolic acids and sugar

215
Q

what is a characteristic of the lipid coat of mycobacteria

A

it is antiphagocytic

216
Q

structure of mycobacteria

A

peptidoglycan layer intertwined with arabinogalactan polymer and surrounded by lipid coat

217
Q

how is the peptidoglycan layer of mycobacteria attached to arabinogalactan polymer

A

covalently

218
Q

what is the function of peptidoglycan in acid fast cell wall (mycobacteria)

A

prevents osmotic lysis

219
Q

what is the function of mycolic acids and other glycolipids in mycobacterial cell wall

A

impede the entry of chemicals —

  • the organisms grow slowly
  • are more resistant to chemical agents and lysosomal components of phagocytes
220
Q

what is the function of surface proteins in acid fast cell wall

A

enzymes

adhesins

221
Q

what do adhesins do

A

they enable the bacterium to adhere intimately to host cells and other surfaces in order to

  • colonise
  • resist flushing
222
Q

what is the role of periplasm in acid fast bacteria

A

Enzymes for nutrient breakdown

periplasmic binding proteins to facilitate transfer of nutrients across cytoplasmic membrane

223
Q

MoA of isoniazid

A

it inhibits mycolic acid biosynthesis

224
Q

Ghon focus aka

A

tubercle

225
Q

What is a tubercle

A

small, rounded nodule produced by infection by Mtb.

226
Q

what is the primary lung lesion of pulmonary TB

A

Ghon focus (tubercle)

227
Q

Ranke complex

A

the result of ghon focus that has healed, fibrosed and is sometimes calcified

228
Q

what is a major factor in the cariogenicity of S mutans

A

its ability to adhere to tooth surface

229
Q

how is S mutans able to adhere to tooth surface?

A

presence of an extracellular glycocalyx

230
Q

extracellular glycocalyx aka

A

capsule

231
Q

what is the major function of the capsule in certain bacteria

A

to protect them against phagocytosis by eukaryotic cells

232
Q

other important functions of the capsule

A
  • mediate adherence of cells to surfaces

- identification purposes

233
Q

how are capsules used to identify bacteria

A

polysaccharide capsules when treated with antiserum swell, allowing them to be identified

234
Q

what kind of capsule surrounds the cells of strains of streptococcus pneumoniae

A

polysaccharide capsules - they are antiphagocytic

235
Q

the virulence of which bacteria is enhanced by capsule production?

A
  • Haemophilus influenzae
  • Klebsiella pneumoniae
  • Cryptococcus neoformans
236
Q

What % of plasma membrane is protein?

A

70% mass

237
Q

Major functions of plasma membrane

A
  • selective permeability
  • electron transport
  • excretion of hydrolytic exoenzymes
  • bearing useful enzymes
  • bearing receptors
238
Q

Main role of cell wall

A
  • rigidity for cell
  • strength
  • protection against mechanical stress
  • essential role in cell division
  • primer for its own biosynthesis
239
Q

which one is thick, gram + or - cell wall

A

Gram +

240
Q

how much of the cell wall does murein make up in gram + bacteria?

A

90%

241
Q

thickness of gram + cell wall

A

15 - 80 nm

242
Q

thickness of gram - cell wall

A

10 nm

243
Q

which one is more complex - gram + or - cell wall?

A

Gram - cell wall

244
Q

which one - gram + or gram -ve have lipoprotein as integral elements of cell wall?

A

Gram -ve

245
Q

What apart from murein makes up gram +ve cell wall?

A

Teichoic acids

246
Q

What is the role of teichoic acids in gram +ve cell wall?

A

attachment sites for bacteriophages

247
Q

What apart from murein make up a part of gram -ve cell wall?

A

Lipoproteins
Lipopolysaccharide layers (endotoxin)
Phospholipids
Proteins

248
Q

What does the gram -ve cell wall have that gram +ve doesn’t?

A

Proteins, lipopolysaccharide layers and phospholipids, that form the cell envelope - it protects the cell from antibiotics and enzymes

249
Q

Function of cell envelope in gram -ve bacteria

A

Protection from antibiotics like penicillin and enzymes like lysozyme

250
Q

Definitive component of murein is

A

N-acetylmuramic acid which is contained in all bacterial peptidoglycans

251
Q

What is the factor that distinguishes the archaebacteria from other bacteria?

A

the cell walls of archaea may be composed of protein, polysaccharides or peptidoglycan-like molecules, but never murein

252
Q

What do most species of lactic acid bacteria ferment glucose to?

A

Lactic acid (duh)

253
Q

Most common application of lactobacillus

A

Industrial - for dairy production

254
Q

What part of the body do lactobacilli generally naturally occur in

A

vagina

255
Q

why are lactobacilli abundant in the vaginal area

A

as they create an acidic environment derived from glucose, they inhibit growth of many bacterial species that can lead to urogenital infections

256
Q

what is the most probable cause of the frequent association of lactobacilli with dental caries?

A

secondary microbial invaders

257
Q

what is the most commonly associated lactobacillus with dental caries

A

Lactobacillus casei

258
Q

what lactobacillus is added to milk to assist lactose intolerant individuals?

A

Lactobacillus acidophilus - it helps them digest lactose sugars

259
Q

How does lactobacillus acidophilus help with lactose intolerant individuals?

A

It converts milk sugars to products that do not cause GI problems

260
Q

Lactic acid bacteria include

A

Lactobacillus

Streptococcus

261
Q

Why are lactobacillus and streptococcus both lactic acid bacteria?

A

They use the lactic acid fermentation pathway

262
Q

What happens in the lactic acid fermentation pathway

A

Pyruvate is reduced to lactic acid

263
Q

Aciduric bacteria

A

another name for the lactic acid bacteria, as they can tolerate an acid environment

264
Q

Lactic acid bacteria aka

A 
Aciduric
Acidogenic (acid forming)
265
Q

Main culprit in dental caries

A

Strep mutans

266
Q

What kind of caries is Strep mutans especially implicated in?

A

Smooth surface caries

267
Q

What kind of problems does lactobacillus cause in humans?

A

It’s generally harmless

268
Q

What is the relationship of lactobacillus to antibiotics?

A

It is resistant to vancomycin

Treated with high doses of penicillin in combination with gentamycin

269
Q

Name a causative agent of root caries

A

Actinomyces

270
Q

Two organisms most commonly associated with the etiology of localized aggressive periodontitis

A

Capnocytophaga ochraceus

Actinobacillus actinomycetemcomitans

271
Q

forms of aggressive periodontitis

A

Generalized

Localized

272
Q

Predominant microbes in generalized aggressive periodontitis

A

Prevotella intermedia
Elkenella corrodens

(gram negative anaerobes)

273
Q

At what ages does generalised aggressive periodontitis occur

A

12-25 years of age

274
Q

What are the characteristic features of generalised aggressive periodontitis

A

Rapid, severe periodontal destruction around most teeth

Episodic, rapid, and severe attachment loss

275
Q

In what kind of patient does localised aggressive periodontitis occur

A

otherwise healthy adolescents - 12-19 years of age

276
Q

Characteristic features of localised aggressive periodontitis

A
  • rapid and severe attachment loss confined to the incisors and first molars
  • relative absence of local factors to explain the severe periodontal destruction
277
Q

at what pH does S mutans grow optimally?

A

well below 7 - acidophilic

278
Q

what points determine the range of pH over which an organism can grow?

A

minimum pH
maximum pH
optimum pH

279
Q

What are bacteria that grow best at neutral pH (7.0) called?

A

neutrophils

280
Q

What are most bacteria - acidophils, neutrophils or basophils?

A

neutrophils

281
Q

name some neutrophilic bacteria

A
  • Pseudomonas aeruginosa
  • Clostridium sporogenes
  • Proteus spp
282
Q

Name some acidophilic bacteria

A
  • Thiobacillus thiooxidans
  • Sulfolobus acidocaldarius
  • Bacillus acidocaldarius
283
Q

What are obligate acidophiles?

A

Bacteria that actually require low pH for growth as their membranes dissolve and the cells lyse at neutrality

284
Q

examples of alkaliphiles

A

Nitrobacter spp

Streptococcus pneumoniae

285
Q

Aciduric vs Acidogenic

A

Aciduric bacteria are capable of or can tolerate living under acid conditions, while acidogenic bacteria produce high concentrations of acid

286
Q

What are the primary acidogenic microorganisms of the oral cavity?

A

Streptococci

287
Q

What is the main cause of enamel decalcification?

A

Lactic acid

288
Q

Most well-known enteric bacteria

A

E coli
Shigella
Salmonella

289
Q

Infections that E coli is responsible for in humans

A

UTIs
Neonatal meningitis
intestinal diseases

290
Q

what are capnophilic bacteria

A

bacteria that require carbon dioxide for growth

291
Q

example of capnophilic bacteria

A

Capnocytophaga ochraceus

292
Q

are streptococci gram + or gram -ve?

A

Gram +ve

293
Q

what kind of metabolism do streptococci have

A

facultative anaerobes or capnophilic

294
Q

which ones are catalase negative - strep or staph?

A

strep

295
Q

What is one of the most frequent pathogens of humans?

A

Strep pyogenes (group A streptococcus)

296
Q

Order of phases of phagocytoses

A 
chemotaxis
adherence
ingestion
phagosome 
phagolysosome 
digestion
residual body
discharge
297
Q

Types of phagocytes

A

Fixed

Free

298
Q

types of fixed phagocytes

A

(do not circulate)
fixed macrophages
cells of reticuloendothelial system

299
Q

Types of free phagocytes

A

(circulate in bloodstream) leukocytes

free macrophages

300
Q

What kind of hb has gamma chains?

A

Fetal globin - 2 alpha and 2 gamma chains

301
Q

describe structure of heme

A

nitrogen containing organic pigment molecule that has a single atom of ferrous iron

302
Q

where does hb combine with co2?

A

protein portion

303
Q

how much higher is carbon monoxide affinity for hb than oxygen

A

240x

304
Q

how is pH related to hb affinity for o2?

A

directly proportional

305
Q

can methemoglobin function as an oxygen carrier

A

no because it has iron in ferric state

306
Q

additional function of hb in blood

A

H+ buffer - deo2 hb is less acidic than oxyhb therefore ideally suited to buffer h+ ions coming from tissue CO2

307
Q

Most common form of Hb in adults

A

Hb A

308
Q

Hb H is composed of what kind of chains?

A

4 beta chains

309
Q

What causes formation of Hb H?

A

Defect in 3 of the 4 alpha chain genes

310
Q

What is Hb H an indicator of?

A

Alpha thalassemia

311
Q

What Hb has valine instead of glutamic acid in the beta chain?

A

Hb S

312
Q

What does the presence of Hb S cause?

A

Change in shape of RBC when exposed to decreased amounts of oxygen - sickle shape

313
Q

When might an rbc be exposed to reduced amounts of oxygen

A
  • exercise

- peripheral circulation

314
Q

In which people is HbS the predominant form of Hb?

A

People with sickle cell anemia

315
Q

Where do you see decreased solubility of deoxy form of Hb

A

Sickle cell anemia

316
Q

Hb M

A

Group of Hb in which a single amino acid substitution favors formation of methemoglobin

317
Q

What kind of Hb is associated with methemoglobinemia

A

Hb M

318
Q

What is the normal kind of Hb?

A

Hb A

319
Q

In what kind of Hb has lysine replaced glutamic acid?

A

Hb C

320
Q

What do you see in people with high Hb C?

A

Reduced plasticity of rbcs

321
Q

List types of Hb

A 
Hb A
C
M
H
S
322
Q

90:10 erythropoietin production to which organs in normal adults?

A

kidneys, liver

323
Q

what kind of molecule is erythropoietin

A

a glycoprotein

324
Q

how is the production of erythropoietin regulated?

A

a negative feedback mechanism that is sensitive to the amount of oxygen delivered to the tissues

325
Q

what does inadequate erythropoiesis lead to?

A

anemia
increased cardic output
hypoxia

326
Q

What does anoxia lead to?

A

greater production of erythropoietin

327
Q

what is the site of action of erythropoietin

A

hemocytoblast

328
Q

what is the hemocytoblast

A

pluripotent stem cell

329
Q

what is anoxia

A

low oxygen

330
Q

what does excessive erythropoiesis lead to

A
  • polycythemia
  • increased blood viscosity
  • sluggish blood flow
331
Q

what is a hallmark of anemic people wrt oxygen in blood?

A

normal oxygen tension

reduced oxygen content in systemic arterial blood

332
Q

diameter of rbcs

A

7-8 microns

333
Q

what do rbcs contain

A

Hb

Carbonic anhydrase in large quantity

334
Q

what does carbonic anhydrase do

A

converts carbon dioxide and water to bicarbonate and proteins

335
Q

what is the lipid membrane of rbcs made of

A

lipoproteins

specific blood group substances

336
Q

what is a good indication of amount of erythrocyte destruction per day?

A

amount of bile pigments excreted by the liver per day

337
Q

erythrocyte production in early embryo

A

yolk sac

338
Q

erythrocyte production in mid-gestation

A

mostly liver
spleen
lymph nodes

339
Q

At what stage of life are erythrocytes exclusively produced in bone marrow?

A

from final month of gestation to about 20 years old

340
Q

After the age of 20, where are erythrocytes produced?

A

marrow of membranous bones such as vertebrae
sternum
ribs
ilia

341
Q

what are the factors that cause the oxyhb dissociation curve to shift to the right?

A

increased co2 concentration
increased blood temperature
increased 2,3 - biphosphoglycerate
decreased pH

342
Q

What are the characteristics of active tissues?

A

during active muscle contraction:

lactic acid is produced, co2 is produced by the tissues and heat is produced

343
Q

How does lower pH shift the curve to the right?

A

Acidic conditions decrease the affinity of Hb for o2 because the higher the H+ concentration, the less o2 is bound to Hb

344
Q

how does increased arterial pco2 affect the oxyhb dissociation curve?

A

co2 molecules bind with Hb and alter Hb conformation from the R state to the T state (low oxygen affinity)

345
Q

what is intrinsic factor essential for

A

absorption of vitamin b12 in the ileum

346
Q

what cells secrete intrinsic factor?

A

parietal cells

347
Q

what is the stomach lining made of

A

columnar epithelium folded into gastric pits

348
Q

what is a gastric pit

A

the opening of a duct into which one or more gastric glands empty

349
Q

how many distinct regions is the gastric mucosa divided into

A

three-
oxyntic or parietal
cardiac glandular region
pyloric gland region

350
Q

where is the cardiac glandular region located

A

just below the lower esophageal sphincter

351
Q

what kind of cells does the cardiac glandular region contain

A

mucus secreting gland cells

352
Q

what kind of secretions does the oxyntic region have

A

acidic

353
Q

where is the parietal gland region situated?

A

above the gastric notch (equivalent to the proximal part of the stomach)

354
Q

where is the pyloric gland region situated

A

below the notch

355
Q

what are the two important types of glands in the stomach mucosa

A

oxyntic

pyloric

356
Q

oxyntic glands aka

A

gastric glands

357
Q

what do the oxyntic glands secrete

A

hydrochloric acid
pepsinogen
intrinsic factor
mucus

358
Q

What do pyloric glands secrete

A

mainly mucus

hormone - gastrin

359
Q

what is the difference between pyloric and oxyntic glands

A

pyloric have no peptic cells and almost no parietal cells

NBDE 1 (4 decks)

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