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Microbiology PMY 3 > Relationships 2 > Flashcards

Relationships 2 Flashcards

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Biology 101 flashcards
1
Q

What is entry?

A

Initial step in the infectious process

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2
Q

What is adhesion?

A

Adherence to host cells through specific interactions between molecules on the pathogen and molecules on these host cells

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3
Q

What are the microbial adhesion factors?

A

Bacterial- bacterial adhesions
-capsule, fimbrae, pili

Viral- viral adhesion

Viral capsid, viral membrane envelope

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4
Q

What is the function of fimbrae/pili?

A

Helps bacterial cells adhere to surfaces

F pili/sex pili enables conjugation/ dna transfer

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5
Q

What are the functions of viral caspid or membrand envelope adhesins?

A

Helps with adherence to specific proteins, glycoproteins or carbohydrate residues on the host cells surface

Virulence factors with similar functions to bacterial ashesins which facilitate adhesion to host cells

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6
Q

What natural environmen5 has microorganisms attached?

A

Rocks (in a stream) In roots of plants

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7
Q

What might Microorganisms attach to in medical environments?

A
  • dental plaque leading to dental caries and gum disease
  • Prosthetic heart valves leading to infective endocarditis, intracardiac abscess
  • joint prosthesis leading to prosthetic joint infections
  • internal catheters leading to catheter related infections
  • medical device implants leading to blood stream infections
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8
Q

What might microorganisms attach to in the industrial environment?

A

Food and beverage industries leading to food safety problems

Water processing plants leading to water quality issues

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9
Q

Describe biofilm formation

A

Planktonic

  1. Attachment to surface
  2. Formation of mono layer and production of matrix
  3. Microcolony formation, multi-layer
  4. Mature biofilm, with characteristic “mushroom” formed of polysaccharide
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10
Q

What is tissue tropism?

A

Phenomenon by which certain host tissues preferentially support the growth and proliferation of pathogens.

Organ and tissue tropism reflects the ability of a given pathogen to infect a specific organ or a set of organs

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11
Q

What is colonization?

A

The process of infection continues with colonization, with or without damage to host tissue

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12
Q

What are the outcomes of colonization?

A

Commensalism- human microbiome, acquisition starting at birth

Infection- these microorganismmay be from exogenous or endogenous sources and have the potential to cause damage to host tissues

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13
Q

What are the conditions of colonization?

A
  1. Environments

2nutrient acquisition

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14
Q

What environmental factors contribute to colonization?

A
  • pH( h pylori colonizers the stomach ph2-4)
  • moisture (corynebacterium colonizers skin)
  • temperature
  • oxygen content
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15
Q

What factors of nutrient acquisition contribute to colonization?

A

Iron

  • host cells
    • transferrin andlactoferrin compete for iron acquisition
  • pathogens
    • siderphores
    • breakdown of iron containing compounds

e. g. N meningitis is
- lactoferrin and transferrin receptors
- hemoglobinreceptors

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16
Q

What determines occurrence if disease?

A

Host, environment, and infectious agent

17
Q

Give examples of agents

A

Viral/bacterial/ fungi/ reservoirs/ transmission route

18
Q

What factors about host contribute to disease occurrence

A

Age, sex, immune status, genetic predispo, comorbidites

19
Q

What factors of environment contribute to disease occurrence?

A

Tropical or temperate countries, sanitation levels, population density, socioeconomic status, vector exposure

20
Q

Contrast infection vs disease

A

STI DONT EQUAL STD

infection- any situation where a microorganism gains entry, becomes established and is growing in a host, whether or not the host is yet harmed

Disease: growth of microorganism, invading pathogen or commensal results in host damage and production of specific signs

21
Q

What are the bacterial virulence factors?

A
  1. Toxins.
  2. Flagella
  3. Glycocalyx
  4. Bacterial enzymes
22
Q

What are toxins?

A

Bacterial proteins encoded by the bacterial chromosomal genes or extrachromosomal genes (plasmids, phages)

23
Q

What are endotoxins?

A

Bacterial toxins secreted from the cells, which bind to specific cell receptors or structures causing a specific action on host cells or tissues

Site of action: neurotoxin, enterotoxin, cytotoxin

24
Q

Give 2 examples of neurotoxins and there purpose

A

Clostridium botulinum and Clostrudium tetani

Botulinum toxin(Botox) in low concentrations is used for cosmetic and medical procedures

Before the advent of the DTP/. DTaP/ diphtheria and tetanus toxoids(DT), tetanus incidence rates= mortality rates

25
Q

Give an example of an entertoxin and how it works

A

Entertoxin: cholera toxin

Enterotoxins are exotoxins

B sub unit binds to ganglioside receptor of epithelial cell

A subunit gets inside cell to activate G-protein and activate Adenylyl cyclase pathway

Causes release of water, sodium and chloride ions

26
Q

What are endotoxins?

A

Toxic component of bacteria outer membranes

Lipopolysaccharide of gram negative bacteria. Usually has a general effect on host cells and tissues causing symptoms of inflammation and fever

The lipid component of endotoxins, lipid A, is responsible for the toxic properties of the LPS molecule

27
Q

Give examples of endotox7ns

A

Salmonella spp: LPS—> gastroenteritis (food poisoning)

N. Meningitidis—> meningococcal meningitis or septicemia

28
Q

Describe flagella as a bacterial virulence factor

A

Long, thin protrusions from the body

Function:

  • bacterial motility
  • bacterial adhesion
29
Q

Describe glycocalyx (capsule/slime layer) as a bacterial virulence factor

A

Coating outside the cell wall of both gram positive and gram negative bacterial cells

Usually consists of polysaccharide but can also ne composed of other materials; glycoprotein etc.

Function- enhances pathogenicity by preventing phagocytosis by host immune cells

30
Q

Describe bacterial enzymes as bacterial virulence factors

A

Bacterial proteins which can participate in catalytic reactions. These reactions may be helpful in bacterial cell invasion, host cell evasion and in some cases laboratory identification.

Invasins:

Hyaluronidase
Streptokinase
Staphylokinase

Hemolysins

Catalase

31
Q

What is antigenic variation (discuss as a viral virulence factor)

A

Occurs mostly in certain types of enveloped viruses

Antigenic drift- a result of point mutations causing slight changes in surface glycoproteins

Antigenic shift- a major change in surface glycoproteins due to gene assortment

E.g. influenza virus

  • orthomyxovirudae family
  • single stranded negative sense RNA genome
  • segmented genome(7-8)

Microbiology PMY 3 (24 decks)

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