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S1B4: MedMicro > Intro to microbiology > Flashcards

Intro to microbiology Flashcards

1
Q

What are the 3 domains of life?

A

Archaea, Bacteria, and Eukarya

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2
Q

What are the differences between prokaryotes and eukaryotes?

A
  1. presence of nucleus
  2. structure of ribosomes
  3. enzymes involved in DNA replication/RNA synthesis
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3
Q

What eukaryotes cause disease?

A

Fungi, protazoa, parasitic worms (helminths), ectoparasitic arthopods

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4
Q

What are the two classifications that make up the scientific name of an organism? Which one is capitalized?

A

genus and species

genus is capitalized

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5
Q

What is the name of microbes living in and on our bodies? Where on our bodies do they live? What is the name of their collective genome?

A

microbiota
skin, nares, oral cavity, intestines, and genitourinary tract
microbiome

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6
Q

What are the possible shapes of bacteria and what are their names (singular and plural)?

A
  1. spheres [cocci (pl.) coccus (sing.)]
  2. rods [bacilli (pl.) bacillus (sing.)]
  3. spirals [spirilla (pl.) spirillum (sing)]
  4. slightly curved rods (vibrios)
  5. flexible spirals [spirochaetes]
  6. short rods [coccobacilli]
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7
Q

What is the name for bacteria that adopt multiple shapes?

A

pleomorphic

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8
Q

What are the typical bacterial arrangements and their names?

A

diplococcus or diplobacillus (two cells), streptococcus or streptobacillus (chains), and staphylococcus (clusters)

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9
Q

What is the typical size range of bacteria? What instrument are they visible with?

A

0.2-0.5 micrometers

light microscope

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10
Q

What are plasmids? What do they frequently carry?

A 
Extrachromosomal genetic material
often required for virulence
1. genes for antibiotic resistance
2. genes for adherence to host cells
3. toxin genes
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11
Q

Name the difference in bacterial and eukaryotic organelles

A

Bacteria–> no ER, Golgi, or lysosomes
bacterial ribosomes = 70S
eukaryotic ribosomes= 80S

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12
Q

Name of bacterial cell asexual reproduction

A

Binary Fission

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13
Q

Gram Staining Characteristics:
color after staining, membrane components

Why is this an important identification?

A

Gram positive:

  • purple after staining
  • cell wall peptidoglycan (thicker)
  • teichoic acids

Gram negative:

  • pink after staining
  • cell wall peptidoglycan (thinner)
  • outer membrane–> (outer half) lipopolysaccharide (LPS) (inner half) phospholipids

Important to know when determining treatment plan.

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14
Q

Accumulation of this protein can cause septic shock during an infection by a gram negative bacteria. Why does this happen?

A

LPS

excessive inflammatory response

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15
Q

What is the name of proteins on the outside layer of gram negative bacteria that for pores or channels? What is their function?

A

porins

small molecules can diffuse passively

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16
Q

What is the procedure used to identify organisms resistant to Gram staining. Name an example of an organism that would require this type of identification.

A

Acid-fast
use to identify bacteria with waxy cell wall
Mycoplasmas– lack a cell wall
Mycobacterium tuberculosis (causal agent TB)

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17
Q

Describe a bacterial capsule. What is its purpose?

A

gelatinous layer that surrounds bacterium composed of mainly polysaccharides
inhibits phagocytosis

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18
Q

What are protein fibers that rotate and allow bacterial cell to move through fluids?

A

flagella

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19
Q

What are proteinaceous rod-like structure on surface of bacteria that allow adherence to various surfaces? Why are they important?

A

Pili (sing. pilus)

Important for colonization and initiation of infection

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20
Q

In what conditions would bacteria produce spores/endospores?

Describe the structure of spores and to what they are resistant.

What are medically relevant bacteria that form spores?

A

When nutrients such as C or N are scarce and allows the bacteria to remain dormant for years

Spores have thick multilayer coat, highly dehydrated, contain bacterial DNA with small amounts cytoplasm. They are resistant to heat, chemicals, and desiccation.
When favorable conditions return, the bacteria reconvert to metabolically active cells.

Example: Clostridium (tetanus and botulism) and Bacillus (anthrax)

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21
Q

What is a biofilm? Where do they grow?

A

communities of bacteria embedded in a polysaccharide matrix that adhere to a surface
mucosal surfaces, teeth, implanted devices, catheters

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22
Q

What is the name for bacterial that only replicate inside the host cell? What is an example of this type of bacterai?

A

obligate intracellular parasites

Example: Chlamydia

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23
Q

What is the name of bacteria that have complex nutritional requirements?

A

nutritionally fastidious

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24
Q

What does it mean for a bacteria to be a:

  1. strict anerobe
  2. strict/obligate anaerobe
  3. facultative anaerobes
  4. microaerophile
A
  1. oxygen must be present for the organism to grow (divide)
  2. cannot grow in the presence of oxygen
  3. can grow whether or not oxygen is present
  4. grow best at low oxygen concentration
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25
Q

What is a unique ability of strict anaerobes and facultative anaerobes?

A

the ability to ferment sugars, producing acids as a by-product

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26
Q

What conditions are important for bacterial growth? What are mesophiles?

A

temperature and pH

bacterial that can grow between 25-40 degrees celciius

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27
Q

What is the typical pH conditions that medically relevant bacteria are able to grow? What is an example of a bacteria that is an exception to this rule?

A 
pH 7.2-7.4
Helicobacter pylori (causal agent or gastric ulcers) grows in the stomach (low pH)
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28
Q

Why is it important to know environment and nutrient requirements of an organism?

A

so that clinical specimens are cultured under the appropriate conditions

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29
Q

What is a selective component in bacteria cultures? What is an example?

A

have components that inhibit the growth of some organisms but not other
bile salts inhibit the growth of gram positive organisms but not gram negative

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30
Q

What is the name of visible bacterial masses found on solid media cultures?

A

colonies

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31
Q

What are differential media cultures? What is an example?

A

contain an indicator

a dye the changes color due to metabolic activity,

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32
Q

What are the criteria through which most medically important bacteria are identified?

A

morphology, staining properties, cultural requirements, and biochemical properties

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33
Q

What is the study of fungi called? Fungal infections?

A

mycology and mycosis

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34
Q

What are the qualities of media cultures intended to promote fungal growth?

A

inhibit bacterial growth

– acidic pH or addition antibiotics

35
Q

What are the three components of fungal cell membrane?

Name the major identifiable difference between mammalian and fungal cell membranes.

A

lipids, glycoproteins, and sterols
fungal sterol: ergosterol
mammalian: cholesterol

36
Q

What are the components of fungal cell walls?

A

carbohydrates (chitin, mannan, glucan)

37
Q

What is the name for fungal asexual reproductive spores? Do fungi always reproduce asexually?

A

conidia

no, they also reproduce sexually

38
Q

Name the major differences between yeasts and molds:

A 
Yeast:
*unicellular
*spherical/ovoid form
*2-5 micrometers
*divide forming buds (daughter cells)
*identified through fermentation and assimilation of 
 carbohydrates

Molds

  • multicellular–> colony = mycelium
  • part of mycelium grows into medium to provide nutrients to aerial hypae forming a “fuzzy” outgrowth
  • identified through color and texture of colonies as well as the specialized reproductive structures
39
Q

What group of people are most susceptible to fungal infections and where are the two places from which those infections usually arise?

A

immunosuppressed people

fungi of the microbiota or after exposure to environmental fungi

40
Q

What are the four divisions of mycosis?

A
  1. superficial and cutaneous: fungus grown on body surfaces
  2. subcutaneous: involve subcutaneous tissue and rarely disseminate
  3. opportunistic: infections caused by fungi present in the environment or the microbiota that normally do not affect healthy people
  4. systemic or endemic mycosis: include fungi capable of infecting healthy individuals
41
Q

What is the general size of protazoa? Are they multicellular or single-cellular organisms?

A

2-100 micrometers

single-celled

42
Q

How to protozoa move?

A

simple cytoplasmic extrusions (pseudopods) OR

more complex structures (cilia and flagella0

43
Q

What types of cells do intracellular protozoa infect?

Where are non-intracellular protozoa found?

A

Red blood cells, macrophages, epithelial, brain, muscle

blood, intestine and genitourinary system

44
Q

Describe a protozoa cyst

A

produced during harsh environmental conditions

the cyst is surrounded by thick cell wall that provides protection and facilitates transmission via fecal-oral route

45
Q

What are the 3 modes of transmission for protozoa?

A

ingestion, sexual contact, insect vector

46
Q

What form of reproduction is utilized by potozoa?

A

Asexual inside humans

may engage in sexual reproduction inside insect vectors

47
Q

What are examples of disease causing protozoa?

A

malaria, dysentery, chagas disease and leishmaniasis

48
Q

What is the general size of helminths? What size are the larvae? Are the multi-cellular or uni-cellular?

A

multicellular (primitive nervous and excretory system– no circulatory system) and are millimeters to meters
larvae are 100-200micrometers

49
Q

Where are helminths and protozoa most commonly fond?

A

tropical and subtropical regions

50
Q

What are the common modes of helminth transmission?

A
  1. fecal-oral (swallowing eggs/ larva)
  2. ingestion larva present in tissue of another host (beef, pork, or fish)
  3. penetration fo skin by larva
  4. injection by blood-sucking insects
51
Q

How do helminths attach? Where are these structures located?

A

hooks, suckers or teeth usually located anteriorly

52
Q

How do helminth’s reproduce?

A

majority do not replicate within host, but release eggs in fecal material as a result of sexual reproduction

53
Q

What are the two classifications of helminths? What are their characteristics?

A

Nematoda (round worms):

  • intestinal parasites or infect blood, lymphatics or subcutaneous tissue
  • hookworms have teeth (buccal plaques) to attache to intestinal wall and feed on blood

Cestoda (tapeworms)

  • anterior part or scolex with hooks/suckers to attache to intestine
  • segmented body

Trematodes (fluke/flatworms):

  • non-segmented body
  • oral and ventral suckers- attachment and migration
  • schistosomes (blood flukes)= most important in terms of prevalence and severity of disease
54
Q

What are the three characteristics in determining severity of helminthic infection?

A

size, movement and longevity

  • blockage of internal organ, pressure exerted by growing parasite
  • migration larval forms through body damages tissue
  • host inflammatory response is often damaging
55
Q

What is the exoskeleton of arthropods composed of?

A

chitin

56
Q

What is the name for organisms the live in on or on the host’s skin from which they take their nourishment?

A

ectoparasite

57
Q

What are the two divisions of arthropods and their characteristics? Provide examples of organisms from each classification.

A 
Arachnids
*8 legs
*Example: spiders, ticks, and mites
Insects
*6 legs
*Example: mosquitoes, flies (tsetse, sandflies), lice, fleas, deduviid bugs, and bedbugs
58
Q

What is an example of an arthropod acting as a carrier?

A

depositing infectious agent in the environment

Example: house flies or cockroaches carrying bacterium Shigella

59
Q

What is an example of an arthropod causing direct damage to the host?

A

human itch mite (Sarcoptes scabiei var. hominis) causes scabies

60
Q

What is the name of the viral characteristic that they are only able to multiply inside living cells due to a lack fo organelles and metabolic activity?

A

obligate intracellular parasites

61
Q

What is the size of viruses? Through which devise are they visible?

A

10-100 nanometers

observed through electron microscopy

62
Q

What are they types of genome found in viruses?

What are the possible configurations?

A

DNA, ssRNA, dsRNA, ssDNA and dsDNA

linear or circular and can consist of one or more fragments

63
Q

What is the name of the protein shell surrounding viral nucleic acid?

What additional outer structure is present in some viruses?

A

capsid

lipid outer envelope –> acquired from host cell nucleocapsid/ It contains specific viral proteins

64
Q

Name and describe the three type of nucleocapsids:

A

Icosahedral symmetry: protein molecules are arranged in the shape of an icosahedron (polyhedron with 20 faces)

Helical symmetry: the capsid surrounds the nucleic acid int eh form of a helix or spiral to form a tubular nucleocapsid

Complex symmetry: exhibited by few families, for example, the human immunodeficiency virus (HIV)shows a pyramid-shaped central core

65
Q

What are the classification criteria for viruses?

A

symmetry, presence/absence envelope and nucleic acid characteristics

66
Q

What are infective glycoproteins devoid of nucleic acid?

A

prions

67
Q

What is the name of the chronic diseases caused by prions?

What are their characteristics?

A

transmissible spongiform encephalopathies

chronic, long incubation (up to 20 yrs), fatal

68
Q

What is the native and diseased identification of prion proteins? What is the cause of this change?

A

PrP^c (native)
Prp^Sc (diseased)
change in conformation from alpha-helical to insoluble beta-sheet structure

69
Q

How does Prp^Sc replicate?

A

Prp^Sc replicates upon interaction with native Prp^c, changes it to the misfolded conformation, which accumulate in vacuoles in neural tissues

70
Q

Prp^Sc is highly resistant to degradation and inactivation by:

A

heat or chemicals

71
Q

What are the three ways human prion diseases are acquired?

A
  1. inheritance of mutations in the PrP gene
  2. spontaneous occurrence (sporadic Creutzfeldt-Jacob disease)
  3. acquisition through environmental exposure (medical procedures, food contaminated with bovine spongiform encephalopathy prions)
72
Q

The use of physical procedures or chemical agents to destroy ALL microbial forms, including bacterial endospores

A

Sterilization

73
Q

use of chemical agents on the skin or other living tissue to inhibit or eliminate microbes; no sporadical action is implied

A

Antisepsis

74
Q

use of physical procedures or chemical agents to destroy most microbial forms on a material or object (bacterial spores and other relatively resistant organisms may remain viable)

A

Disinfection

75
Q

mild heating to reduce the microbial load commonly used in the dairy and other food processing industries

A

Pasteurization

76
Q

Sterilization method:

moist heat sterilization

A

autoclave

77
Q

How does an autoclave work?

A

load is placed in double wall or jacketed chamber
stem circulates at temperature beyond boiling point of water
High temp is maintained for defined amount of time, then restored to atmospheric pressure

78
Q

Sterilization method:
oven, requires prolonged exposure times and higher temperatures

describe when this would be used

A

Dry heat

used for glassware, some powders and oils

79
Q

Sterilization method:
use with media or biologics that are sensitive to heat

describe when this would be used

A

Filtration
Viral-retentive filters, solutions for intravenous use (eliminate endotoxins present in cell wall gram negative bacteria)

80
Q

Sterilization method:
causes DNA damage

describe when this would be used

A

Radiation

medical or dental products, food preservation

81
Q

Sterilization method:
toxic alkylating agent of hydroxyl, carboxyl, amino and sulfhydryl groups

describe when this would be used

A

Ethylene oxide gas
sterilizing heat-sensitive materials, gas must dissipate after sterilization (mutagenic and explosive)
used under defined temperature and humidity

82
Q

Sterilization method:

include aldehydes, hydrogen peroxide and peracetic acid

A

liquid chemicals

83
Q

What are standard precautions taken when interacting with patients?

A
  1. hand hygiene
  2. respiratory hygiene/cough etiquette
  3. safe injection practices
  4. proper disposal of needles and scalpels
  5. Personal Protective Equipment
84
Q

These supplement the standard precautions and are used when the patient is infected or suspected to be infected with a highly transmissible organism

A

transmission-based precautions

S1B4: MedMicro (6 decks)

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