chapter 5 microbiology Flashcards

1
Q

whats a pathogen?

A

microorganism capable of causing disease

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2
Q

what does opportunistic mean?

A

cause disease only in compormised individuals

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3
Q

LD 50

A

“lethal dose” number of organisms needed to kill half the hosts cells

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4
Q

ID 50

A

Infectious dose, number of organisms needed to infect half the hosts

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5
Q

Communicable disease

A

spread from host to host. When a disease is highly communicable it is considered contagious

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6
Q

Endemic

A

constanly present at a low level in a specific population

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7
Q

Epidemic

A

occurs more frequently than usual

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8
Q

pandemic

A

worldwide distribution

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9
Q

stages of infectious diseases are….

A

incubation period, prodomal period, acute specific illness, recovery period.

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10
Q

incubation period

A

time between acquisition of organism or toxin and the commencement of symptoms

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11
Q

prodomal period

A

non specific symptoms like fever and malaise, loss of appetite

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12
Q

acute specific illness

A

specific symptoms start occurring

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13
Q

recovery period

A

illness stops and returns to normal

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14
Q

what are the determinates of pathogenicity?

A

transmission, adherence, invasiveness and toxigenicity

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15
Q

How are pathogens transmitted?

A

inhalation, ingestion, inoculation

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16
Q

name the 4 important portals of entry for pathogens

A

skin, respiratory tract, gastrointestinal tract, genitourinary tract

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17
Q

what are biofilms?

A

aggregates of interactive bacteria attached to a solid surface( including prosthesis). Up to 65% of human infections are associated with biofilms

18
Q

what is a quorum in biofilms?

A

sensing molecules- biofilms secrete this which tend to repulse incoming bacteria or activate the communal bacteria to seek new bodies

19
Q

sessile organisms in biofilms

A

harder to eradicate when sessile

20
Q

planktonic biofilm organisms

A

easier to eradicate

21
Q

what does collagenase and hyaluronidase to for bacteria

A

degrade intercellular substances allowing easy spread of bacteria through tissue

22
Q

what does coagulase do for bacteria?

A

accelerates formation of fibrin clot which helps protect the organisms from phagocytes

23
Q

what does immunoglobulin A protease do for bacteria?

A

kills IgA on mucosal layers

24
Q

leukocidins role for bacteria is …

A

kills neutrophilic leukocytes and macrophages

25
what is pyogenic inflammation?
pus producing
26
what is granulomatous inflammation?
granuloma forming
27
Name some contributing factors fo toxigenicity
endotoxins, fever, hypotension, activation of cascade pathway for inflammation, increased phagocytic activity, increased antibody production
28
Endotoxins
they are the cell wall of lipopolysacharides of gram negative bacteria and are not actively released from the cell. These cause fever, shock, and other general symptoms. Some biological effects are below
29
fever
due to release of IL-1 ( interleukin 1). They act on the hypothalamic temperature regulatory centre and reset it to a higher temperature
30
hypotension-
from release of bradykinin which decrease peripheral resistance
31
exotoxins
highly toxic but have good antigens and induce the synthesis of protective antibodies called antitoxins
32
what are exotoxins categorized into?
neurotoxins, enterotoxins, and miscellaneous exotoxins
33
Name some neurotoxins and what they do
tetanus toxin-blocks the release of inhibitory transmitter which leads to sustained contractions of voluntary muscles diptheria toxin- inhibits protein synthesis in all eukaryotic cells botulinum toxin-blocks release of acetylcholine at the synapse , producing paralysis of both voluntary and involuntary muscles
34
what do enterotoxins do?
increase cAMP which promotes cellular chloride ion excretion and inhibition of sodium ion absorption which leads to diarrhoea
35
natural defeses of the oropharynx and intestinal tract
Continuous desquamation of epithelium, presence of saliva, mucous in intestine, gastric acid, bile and proteolytic enzymes, movements of tonuge and cheek and peristalsis, immune mechanisms
36
Defense mechanisms of respiratory tract
mucous from golblet cells and mucociliary escalator, IgA in respiratory secretions, alveolar phagoytes
37
Defense of genitourinary tract
natural mucosal desquamation, vaginal secretions and cervical mucous, flushing of urine action
38
What is viraemia?
entry of the virus into the blood
39
permissive infection
virus enters host and synthesizes its componets and assembles and are released. Cell usually dies
40
non- permissive infection
transforms the host cell and integrates its DNA into the hosts genome. Cell remains alive