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Medicine Unit 3 > Microbiology pathogenicity: bacteria > Flashcards

Microbiology pathogenicity: bacteria Flashcards

1
Q

why is microbiology important in medicine

A

microbial infections are associated with significant mortality and morbidity
infection is a global problem
antibiotic resistance is an increasing problem with some infections now untreatable with antibiotics
20% of prescriptions are for antibiotics

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2
Q

single-celled bacterial morphologies

A

each cell is separate, each has independent ability to survive and reproduce
large variety in cell shapes
2 most common are cocci and rod-shaped

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3
Q

cocci shape

A

round cells

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4
Q

rod-shaped cells

A

bacilli

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5
Q

monococcus

A

single cells

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6
Q

diplococcus

A

paired cells

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7
Q

staphylococcus

A

grouped cells

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8
Q

streptococcus

A

chained cells

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9
Q

name of a single rod-shaped bacteria

A

bacillus

they also form groups/clusters and chains

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10
Q

components of a bacterial cell

A

plasma membrane
cell wall
cytoplasm
nucleoid
plasmids
ribosomes
capsule
flagella
fimbriae
endospore

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11
Q

label the spore outside to inside

A

exosporium: adherence and biocide protection
coat: resistance
outermsmbrane: permeability barrier to biocides
cortex: resistance to biocides
germ cell wall
inner membrane: impermeability to biocides
core: resistance to heat, UV radiation, gamma radiation, hydrogen peroxide, formaldehyde and other biocides

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12
Q

which is the left picture and which is the right

A

left is gram-negative, double membrane so more difficult to transport
right is gram-positive
spaces are peroplasmic space

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13
Q

what is the spores coat resistant to

A

peroxynitrile
hydrogen peroxide
lysozyme
hydrochlorite
ozone
other biocides
mechanical resistance§

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14
Q

how do spores impact on infection control

A

important vehicles for transmission
have an impact on treatment
make control of spread more difficult

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15
Q

sequence of treatment of infectious disease diagnosis and control

A

observe patient, symptoms
sampling
laboratory observation and culture
identification tests
treatment e.g. antibiotic therapy
observation of population (epidemiology)
prevention of transmission

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16
Q

disease

A

disturbance in the state of heath wherein the body can’t carry out all normal functions

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17
Q

infectious disease

A

due to infection by pathogenic microorganisms

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18
Q

infections

A

invasion by and multiplication of a pathogenic microbe within or on a host

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19
Q

contamination

A

the presence of microbes in a location/environment

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20
Q

Koch’s postulates, proving a microbial cause

A

the specific causative agent must be observed in every case of the disease
agent must be isolated from a diseased host and grown in pure culture
when agent is inoculated into healthy but susceptible, hosts the agent must cause the same disease
agent must be re-isolated from the inoculated, diseased host and identified s identical to the original specific causative agent

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21
Q

infections in sinuses/nose

A

strep pneumoniae
h influenza
MRSA
rhinovirus

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22
Q

infections in outer ear

A

staphylococci
streplococci
pseudomonas

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23
Q

infections in inner ear

A

streptococci
haemophilius

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24
Q

infections in throat

A

candida
strep pyogenes
MRSA
viruses e.g. adenovirus

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25
infections in lungs
strep pneumoniae h influenza staphylococcus aureus gram-negative organisms tuberculosis
26
infections in liver
viral hepatitis
27
infections in kidney/bladder
gram-negative organisms from gut
28
infections in cannula sites/moist skin
MRSA streptococci fungi e.g. yeasts or candida
29
infections in CNS
meningococcus strep pneumoniae h influenza viruses: enterovirus and h simplex
30
infections in mouth
staphylococci streptococci anaerobic organisms: bacteroides
31
infections in heart valves
e.g. endocarditis haemolytic streptococcus staphylococcus yeasts
32
infections in the blood
e.g. septicaemia staphylococcus aureus e coli malaria dengue meningococcus
33
infections in the large and small intestine
gram negative: e coli, klebsiella,campylobacter,salmonella C. difficile bacteroides/anaerobes
34
infections in the joints
staphylococci streptococci n.gonorrhoea haemophilius in children
35
infections in the bones
staphylococci salmonella streptococci
36
what is an infection
iceberg concept severe symptoms mild symptoms infection but no symptoms exposure but no symptoms
37
stages of disease progression
encounter entry/establishment spread multiplication damage outcome
38
the disease process: stages 1 and 2
transmission and exposure
39
what does successful transmission and exposure depend on
more microbes the better airborne: size.density,surface features waterborne: density, surface features, hydrophobicity contact: resistance to dessication, spore formation, adhesion tosurfaces distribution on host: into cuts, digestive system, GI system, lungs vectors
40
disease process stages 3 and 4
adherence and invasion
41
critical stages in disease success
adhesion depends on microbe and host features invasion depends om break in surface layers or on active procedures from microbe motility and chemotaxis attachment often via pili or non-fimbrial adhesions penetration of epithelial/ cells capsules may allow survival inside phagocytes virulent bacteria may inject epithelium cells with molecules to change surface features
42
stages 5 and 6 of the disease process
colonisation and tissue damage
43
consequences of disease
growth in tissues requires cells to resist host responses may have to neutralise growth also requires appropriate nutrients, some have limited or specific nutrients which slow or enhance microbial growth tissue damage results from host cell death, accumulation of toxins and tissue degradation
44
normal flora
commensal flora organisms living in benign symbiosis with the host e.g. e.coli, lactic acid bacteria, staph aureus, candida yeast some may be pathogenic but unable to enter disease process, lack attachment to suitable surface
45
host defence/disease resistance
surface defences cellular defenses inflammation cytokines complement system immunity
46
pathgenicity
ability of a pathogen to produce an infectious disease in an organism
47
virulence
relative degree of damage done by a pathogen or the degree of pathogenicity of a pathogen
48
virulence/pathogenicity factor
microbial product or strategy that contributes to virulence or pathogenicity
49
molecule determinants of pathogenicity
attachment to host tissues production and delivery of various factor replication and evasion of immunity damage to host tissues
50
LD50
lethal dose of microbes toxin that will kill 50% of experimentally inoculated test animal
51
ID50
infectious dose required to cause disease in 50% of inoculated test animals
52
which proteins to bacteria employ
adhesins attach to host tissues, usually located on the ends of fimbriae can consist of glycocalyx
53
capsules
prevent phagocytosis attachment streptococcus pneumoniae klebsiella pneumoniae haemophilus influenzae bacillus anthracis streptococcus mutans
54
what is in the image
alpha hemolytic streptococci secret hemolysins that cause the incomplete lysis of RBCs
55
what is in the image
beta hemolytic streptococci secrete hemolysins that cause the complete lysis of RBCs
56
C. Coagulase
cause blood to coagulate blood clots protect bacteria from phagocytosis from WBCs and other host defences staphylococcus aureus are often coagulase positive fibrinogen to fibrin (clot)
57
F. collagenase
breaks down collagen which is found in many connective tissues clostridium perfringens- gas gangrene uses this to spread through tissues
58
what is in the image
tissue damage caused by microbial enzymes of clostridium perfringens
59
toxins
poisonous substances produced by microorgansims they're a primary factor for pathogenicity 220 bacterial toxins that are known, 40% of which cause disease by damaging the eukaryotic cell membrane
60
toxemia
toxins in the blood stream
61
toxigenicity
capacity of micro-organisms to produce toxins
62
two types of toxins
exotoxins endotoxins
63
exotoxins
produced inside mostly gram positive bacteria as part of their growth and metabolism released into the surrounding medium
64
endotoxins
part of the outer portion of the cell wall of gram negative bacteria liberated when the bacteria die and the cell wall breaks apart

Medicine Unit 3 (28 decks)

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