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IHL Exam 2 > Introduction to Pathogens (Bowden) > Flashcards

Introduction to Pathogens (Bowden) Flashcards

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1
Q

Commensalism of flora

A

neither hurt harm nor benefit host

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2
Q

mutualism of flora

A

symbiotic interactions between 2 organisms. both benefit

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3
Q

Most important mutualistic role of flora

A

microbial antagonists by providing bacterial interference

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4
Q

What ways does normal flora do good

A

prevent/suppress pathogens
synthesize vitamins (VitK)
Abs produced to commensals cross react with pathogenic Ag
Bacteriocins
Endotoxin release enhances immune response

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5
Q

Whay ways can normal flora be more harmful than good

A

can become pathogenic in tissues
penicillinase + bacteria interfere with therapy
confusion of Dxs because of resemblence to pathogens
Step vindans seeds bloodstream following dental procedure= heart valve and then infectious endocarditis

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6
Q

Resident flora

A

Interferes via competing for R, nutrients and mutual inhibition by metabolic, toxic products or bacteriocins or antibiotics

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7
Q

Transient flora

A

exposure to environment, does not cause disease or establish residency

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8
Q

Colonization of flora

A

establishment of microbial population- acquisition of new organism

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9
Q

How do children acquire flora

A

contact with adults, other children and the rest of their environment

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10
Q

What type of microbes are found in large intestine and why

A

anaerobic populations because LI kept anoxic by facultative anaerobes

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11
Q

How is facultative flora acquired

A

feces

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12
Q

General factors that contribute to potential pathogens

A

Age, immunization history, prior illnesses or coexisting illness, trauma, nutrition, pregnancy, emotional state

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13
Q

Medical care potential pathogens

A

breaching skin (intravenouse or surgery) or mucosal surfaces (endotrach tubes)
Introduction to foreign bodies
alteration of natural flora with antibiotics and Tx with immunosuppressive drugs

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14
Q

2 basic mechanisms of pathogens

A

invasion of tissue and production of toxins

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15
Q

What is invasiveness

A

ability to invade host tissue

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16
Q

Components of invasiveness

A 
capsules (inhibit phagocytosis)
adaptation (can alter selective tissue invasion)
extracellular enzymes (degrade host tissue)
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17
Q

Virulence

A

the combination of invasiveness and toxigenicity

LD50 % dead vs dose

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18
Q

Is variability of virulence genotypic or phenotypic

A

can be both

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19
Q

How can infectious disease be transmitted? factors?

A

directly or indirectly
Source, number of infectious agents, capability of surviving host defense, % of host that is susceptible ID50 %infected vs dose

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20
Q

Toxigenicity. 2 types

A

production of toxins
Exotoxins- secreted proteins, heat labile. mainly gram + organisms
Endotoxins- LPS gram - bacteria

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21
Q

What is required for pathogen to be pathogenic

A

adhere. evade local immune system, must be able to replicate, must evade systemic immune system. must escape body for transmission to new host

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22
Q

Which pathogens are assoc with chronic diseases? acute?

A

generally intracell pathogens- chronic disease

extracell pathogens- acute disease

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23
Q

Stages of infections

A 
Incubation
Prodomal: non-specific symptoms
Specific-illness period: signs and symptoms
Recovery
Latent
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24
Q

What is a virus

A

obligate intracellular parasite capable of infecting a variety of different cell types

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25
What type of genomic material do viruses have
DNA or RNA ss or ds
26
What covers viruses
protecting genome is the coat protein "capsid" | some viruses also have a phopholipid envelope derived from host cell and surrounds the capsid.
27
Virus replication
``` recognize and attach to host- specific R penetration into host uncoating to release viral genome viral nucleic acids replicate new viral proteins packaged and released ```
28
Penetration of host by virus
1 translocation of PM 2 pinocytosis into cytoplasmic vacuoles 3 fusion of PM with viral envelope
29
3 types of infections from viruses
Abortive: when a virus invades a cell that does not permit viral replication Cytolytic: cell lysis and release of large # of visions Persistent: may be productive, latent or transforming
30
Most common virus
common cold. Rhinoviruses
31
2 modes of rhinovirus transmission
aerosols of respiratory droplets | contaminated surfaces
32
What type of genome are rhinoviruses
ss positive sense RNA and capsid- no envelope
33
What are bacteria
unicellular prokaryotic microorganisms found everywhere
34
Describe Gram + structure
thick peptidoglycan external layer with lipotoic acids. grams iodine cross links in peptidocglycan sheets
35
Describe gram - structure
thin layer of peptidoglycan between 2 phosopholipid bilayers. known as periplasmic space. Also have LPS and lipopolysaccharides
36
What is peptidoglycan
polymer of NAM and NAG
37
Structures of bacteria
cocci, bacilli, coccobacilli, spirochetes
38
How does bacteria move
``` flagella made of flagellins monotrichous lophotichous- several polar flagella amphitrichous several at each end peritichious- covering entire cell surface ```
39
Types of bacterial pili
Pili- surface appendages sex pili- conjugation, transfering genetic information common pili- means for attachment to host and important role in colonization
40
Endospores
resisted to heat, radiation and drying. dormant for years and years germinate then return to vegitative state
41
Describe bacterial structure and what dictates it
high molecular weight polysaccharides. capsule- adhere to cell wall slime layer- loosely associated Controlled by genotype and phenotype
42
Aerobic Bacteria
require oxygen and electron acceptor
43
Anaerobin bacteria
energy from fermentation reactions. O2 can be poisonous
44
Facultative anaerobes
grow under aerobic conditions and can also ferment
45
Distinctive properties of Clostridium difficile
gram +, rod shaped, spore formers, obligate anaerobes, ubiquitous saprophytes, part of normal flora
46
What toxins do the spores of C. difficile make
Toxin A- enterotoxin causing fluid accumulation | Toxin B- cytopathic agent
47
how to antibiotics affect C. difficile.
antibiotic associated colitis | diarrhea cramps pseudomembranous colitis
48
Basic properties of fungi
Grow as either yeast or molds
49
Yeast
single cell, round | form bacteria-like colonies
50
mold
long filament (hyphae) forms a mat (mycelium)
51
Thermally dimorphic fungi
at ambient temp- mold | host tissues- yeast
52
Which fungi is reverse temperature wise
Candidas. at ambient temp-yeast. in host tissues- mold
53
Are most fungi aerobes, anaerobes or facultative anaerobes
aerobes. some facultative. no strict anaerobes
54
What do fungi require to survive
preformed carbon sources
55
structure of fungi
cell wall of chitin. cell membrane contains ergosterol and zymosterol
56
Describe the various mycoses
Superficial (skin and hair) Cutaneous (epidermis, hair nails) Subcutaneous (deeper skin layers) Systemic or deep (internal organs)
57
What causes subcu mycoses and where
caused by free living saprophytic fungi and located deeper layers of dermis wide spread manifestations of chronic infections and granulomatous lesions
58
commonalities of mycoses
patient can remember trauma, location of problem relates to wounds, etiological agents from soil or decaying vegetation resemble bacterial infections Tx involves excision or amputation
59
Describe systemic mycoses
severe disease. immunocompromised most serious dimorphic. no human to human transmission geographical niche most infections are sub clinical
60
Candida albicans
yeast and filamentous cells. Opportunistic. grows in biofilms on devices. Superficial: thrush and vaginitis Systemic: candidemia
61
What is a parasite
when 2 different organisms live together and one harms the other.
62
Parasitic taxomonic groups
Protozoans: single cell with membrane bound nucelus Metazoans: helminthes, nematodes etc.. Arthropods: insects
63
What is a definitive host
final host of host in which a parasite reaches sexual maturity
64
What is an intermediate host
host in which a parasite passes through its larval or asexual stage
65
Accidental host
host other than the usual or normal host
66
Reservoir host
host other than normal but parasite is capable of living and infesting
67
Vector
a carrier, usually arthropod, that transmits causative agent of disease to non-infected
68
Direct transmision examples
Ingestion skin penetration inhalation person-person
69
Indirect transmission examples
vectors | transplantation/transfusions
70
Single host parasites
only human to human contact. oral-fecal
71
Multiple host parasites
require 2 or more hosts to complete life cycle sexual parasitic stage in definitive host a sexual or larval stage in intermediate host
72
Protozoans
most common infectious agent. Eukaryotic, large with tru nucleus cytoplasm:endoplasm and ectoplasm
73
Types of protozoans
trophozoites: active form, fragile Cysts: dormant infective form. they are resilient
74
Nematodes
round worms- spindle shaped eith tough outer cuticle Found in muscular, nervous, reproductive and GI sexes are separate, life cycles complex
75
Soil transmitted helminthiases
contaminated environments. species have different signs and symptoms but usually all can result in: nutritional and cognitive impairment as well as conditions that require surgical intervention
76
Platyheliminthes
tape worms. flattened ribbon shapes. scolex on anterior end. generate proglottids which are their reproductive segments
77
What is the structure of platyheliminthes
no vascular or repiratory systems, no gut or body cavity Has segmented body(strobila) Neck (generates proglottids) Head or scolex (sucking discs or grooves) extensive reproductive system

IHL Exam 2 (11 decks)

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