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

Introduction to Pathogens (Bowden) Flashcards

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
Q

What type of genomic material do viruses have

A

DNA or RNA ss or ds

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26
Q

What covers viruses

A

protecting genome is the coat protein “capsid”

some viruses also have a phopholipid envelope derived from host cell and surrounds the capsid.

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27
Q

Virus replication

A 
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
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28
Q

Penetration of host by virus

A

1 translocation of PM
2 pinocytosis into cytoplasmic vacuoles
3 fusion of PM with viral envelope

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29
Q

3 types of infections from viruses

A

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

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30
Q

Most common virus

A

common cold. Rhinoviruses

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31
Q

2 modes of rhinovirus transmission

A

aerosols of respiratory droplets

contaminated surfaces

32
Q

What type of genome are rhinoviruses

A

ss positive sense RNA and capsid- no envelope

33
Q

What are bacteria

A

unicellular prokaryotic microorganisms found everywhere

34
Q

Describe Gram + structure

A

thick peptidoglycan external layer with lipotoic acids. grams iodine cross links in peptidocglycan sheets

35
Q

Describe gram - structure

A

thin layer of peptidoglycan between 2 phosopholipid bilayers. known as periplasmic space. Also have LPS and lipopolysaccharides

36
Q

What is peptidoglycan

A

polymer of NAM and NAG

37
Q

Structures of bacteria

A

cocci, bacilli, coccobacilli, spirochetes

38
Q

How does bacteria move

A 
flagella made of flagellins
monotrichous
lophotichous- several polar flagella
amphitrichous several at each end
peritichious- covering entire cell surface
39
Q

Types of bacterial pili

A

Pili- surface appendages
sex pili- conjugation, transfering genetic information
common pili- means for attachment to host and important role in colonization

40
Q

Endospores

A

resisted to heat, radiation and drying. dormant for years and years
germinate then return to vegitative state

41
Q

Describe bacterial structure and what dictates it

A

high molecular weight polysaccharides.
capsule- adhere to cell wall
slime layer- loosely associated
Controlled by genotype and phenotype

42
Q

Aerobic Bacteria

A

require oxygen and electron acceptor

43
Q

Anaerobin bacteria

A

energy from fermentation reactions. O2 can be poisonous

44
Q

Facultative anaerobes

A

grow under aerobic conditions and can also ferment

45
Q

Distinctive properties of Clostridium difficile

A

gram +, rod shaped, spore formers, obligate anaerobes, ubiquitous saprophytes, part of normal flora

46
Q

What toxins do the spores of C. difficile make

A

Toxin A- enterotoxin causing fluid accumulation

Toxin B- cytopathic agent

47
Q

how to antibiotics affect C. difficile.

A

antibiotic associated colitis

diarrhea cramps pseudomembranous colitis

48
Q

Basic properties of fungi

A

Grow as either yeast or molds

49
Q

Yeast

A

single cell, round

form bacteria-like colonies

50
Q

mold

A

long filament (hyphae) forms a mat (mycelium)

51
Q

Thermally dimorphic fungi

A

at ambient temp- mold

host tissues- yeast

52
Q

Which fungi is reverse temperature wise

A

Candidas. at ambient temp-yeast. in host tissues- mold

53
Q

Are most fungi aerobes, anaerobes or facultative anaerobes

A

aerobes. some facultative. no strict anaerobes

54
Q

What do fungi require to survive

A

preformed carbon sources

55
Q

structure of fungi

A

cell wall of chitin. cell membrane contains ergosterol and zymosterol

56
Q

Describe the various mycoses

A

Superficial (skin and hair)
Cutaneous (epidermis, hair nails)
Subcutaneous (deeper skin layers)
Systemic or deep (internal organs)

57
Q

What causes subcu mycoses and where

A

caused by free living saprophytic fungi and located deeper layers of dermis
wide spread manifestations of chronic infections and granulomatous lesions

58
Q

commonalities of mycoses

A

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
Q

Describe systemic mycoses

A

severe disease. immunocompromised most serious
dimorphic. no human to human transmission
geographical niche
most infections are sub clinical

60
Q

Candida albicans

A

yeast and filamentous cells. Opportunistic.
grows in biofilms on devices.
Superficial: thrush and vaginitis
Systemic: candidemia

61
Q

What is a parasite

A

when 2 different organisms live together and one harms the other.

62
Q

Parasitic taxomonic groups

A

Protozoans: single cell with membrane bound nucelus
Metazoans: helminthes, nematodes etc..
Arthropods: insects

63
Q

What is a definitive host

A

final host of host in which a parasite reaches sexual maturity

64
Q

What is an intermediate host

A

host in which a parasite passes through its larval or asexual stage

65
Q

Accidental host

A

host other than the usual or normal host

66
Q

Reservoir host

A

host other than normal but parasite is capable of living and infesting

67
Q

Vector

A

a carrier, usually arthropod, that transmits causative agent of disease to non-infected

68
Q

Direct transmision examples

A

Ingestion
skin penetration
inhalation
person-person

69
Q

Indirect transmission examples

A

vectors

transplantation/transfusions

70
Q

Single host parasites

A

only human to human contact. oral-fecal

71
Q

Multiple host parasites

A

require 2 or more hosts to complete life cycle
sexual parasitic stage in definitive host
a sexual or larval stage in intermediate host

72
Q

Protozoans

A

most common infectious agent.
Eukaryotic, large with tru nucleus
cytoplasm:endoplasm and ectoplasm

73
Q

Types of protozoans

A

trophozoites: active form, fragile
Cysts: dormant infective form. they are resilient

74
Q

Nematodes

A

round worms- spindle shaped eith tough outer cuticle
Found in muscular, nervous, reproductive and GI
sexes are separate, life cycles complex

75
Q

Soil transmitted helminthiases

A

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
Q

Platyheliminthes

A

tape worms. flattened ribbon shapes. scolex on anterior end. generate proglottids which are their reproductive segments

77
Q

What is the structure of platyheliminthes

A

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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