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Microbiology > Lecture 1: Basic Microbiology & Bacterial Taxonomy > Flashcards

Lecture 1: Basic Microbiology & Bacterial Taxonomy Flashcards

1) Define Microbiology 2) History of Microbiology (not included) 3) Different types of microbes 4) Differentiate bacteria based on gram stain, morphology, and metabolic characteristics

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1
Q

What is the definition of Microbiology?

A

the study of organisms called microorganisms (microbes) that are too small to be perceived clearly by the unaided human eye

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2
Q

Microbes include:

A

some metazoan animals, protozoa, many algae, and fungi, bacteria, and viruses

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3
Q

Why are microbes probably the most significant life form sharing the planet with humans?

A

because they are ubiquitous in nature, capable of utilizing any available food source, including humans whose defenses may be compromised

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4
Q

Infection

A

the invasion of the body by a harmful microbe resulting in a disease

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5
Q

Disease

A

a disorder with a specific cause and recognizable signs and symptoms

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6
Q

Pathogen

A

any microbe that has the capacity to cause disease

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7
Q

Koch’s Postulates

A

1) pathogen found in diseased organisms, but not healthy
2) able to isolate pathogen from diseased host and grow on culture
3) pathogen from pure culture must cause disease in inoculated healthy animal
4) able to isolate pathogen from inoculated animal

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8
Q

Exceptions to Koch’s Postulates

A
  • some microbes have unique culture requirements or do not grow on cultured media (ie Treponema pallidum, Mycobacterium leprae, rickettssial and viral pathogens)
  • some pathogens do not show distinct symptoms *some diseases involve several pathogens
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9
Q

3 Major microbe categories

A

Viruses
Prokaryotes (bacteria, mycoplasmas, rikettsiae, and chlamydiae)
Eukaryotes (fungi, protozoans, and multicellular parasites)

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10
Q

Prions

A

noncellular infectious proteins, also inherited form

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11
Q

Characteristics of Prions

A
  • long incubation time
  • characteristic spongiform changes associated with neuronal loss and failure to induce inflammatory response
  • prion proteins modify the folding of normal human cellular proteins (cellular proteins or PrP^c) into additional prions (PrP^sc)
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12
Q

Human Prion Diseases

A

Creutzfeldt-Jakob disease (CJD)
Variant Creutzfeldt-Jakob disease (vCJD)
Kuru

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13
Q

Animal Prion Diseases

A

Mad Cow Disease (bovine spongiform encephalopathy)
Chronic Wasting Disease (CWD)
Scrapie

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14
Q

Viruses

- classification
- size
- cellular or noncellular?
- structure
- examples
A

VIRUSES ARE OBLIGATE INTRACELLULAR PARASITES
*smallest and simplest of all microbes (except for prions and viroids)
*NONCELLULAR
*DNA or RNA (not both) enclosed by a protein coat
*may or may not have a lipoprotein envelope
EX: HIV, SARS, Viral Hepatitis (A,B,C,D,E) H1N1

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15
Q

Viral attachment

A

attachment proteins on capsid or envelope determine specificity of infection

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16
Q

Viral reproduction

A

dependent on host cell

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17
Q

Prokaryotes

 - Def
 - Nucleic Acid
 - Organisms
A
  • Unicellular organisms with no clearly defined nuclear membrane
  • Nucleic acid not complexed with histones, no chromosomes
  • Bacteria, mycoplasmas, chlamydiae, rickettsiae
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18
Q

Eukaryotes

- Def
- Nuclear material (arrangement)
- size
A
  • uni- and multicellular organisms with well defined nuclear membranes and organelles
  • nuclear material (nucleic acid plus histones) is arranged in chromosomes
  • usually larger than prokaryotic cells
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19
Q

Fungi

- Prok. or Euk.?
- Cell wall composition
- Major Sterol in membranes
- 4 Types
A

Eukaryotes
*Cell walls containing chitin, glucans, and mannans
*Membranes with ergosterol as major sterol
Include:
-Yeasts (Unicellular)
-Filamentous molds (Mycelia)
-Dimorphic fungi (can grow like yeast or mold)
-Saprophytes (utilize organic matter for energy e.g. mushrooms)

20
Q

Parasite

- Def
- Animal parasite characteristics
A
  • an organism that lives in or on another organism (host) and causes damage to the host
  • animal parasites are euk. organisms with no cell walls, single celled to large organisms, multicellular worms
21
Q

Classification of bacteria is based on what?

A

1) Morphological differences
2) Biochemical/metabolic differences
3) Immunololgic characteristics
4) Genetic characteristics

22
Q

2 common stains for identification of bacteria

A

Gram stain

Acid fast stain

23
Q

Questions to ask when identifying bacteria

A

1) Gram + or Gram -
2) Morphology (rod, coccus, spiral, pleomorphic)
3) Cells occur singly or in chains
4) Size of cells

24
Q

Gram Stain components

A

1) Crystal Violet -primary stain
2) Iodine -mordant
3) Alcohol -decolorizer
4) Safranin -counter stain

25
Q

Cell Wall

- functions
- components
A

semirigid cell wall outside the cell membrane

  • maintains shape
  • prevents cell from bursting
  • porous
  • Peptidoglycan -molecules of N-acetyl glucosamine alternate with N-acetyl muramic acid
26
Q

Gram (+) Amino Acids

Gram (-) Amino Acids

A

G(+): L-Alanine, D-Glutamic Acid, L-LYSINE, D-Alanine

G(-): L-Alanine, D-Glutamic Acid, L-DIAMINOPIMELLIC ACID, D-Alanine

27
Q

Teichoic Acid

- G(+) or G(-)
- Def
- 2 Classes
- Functions
A

Gram (+) only
-polyol phosphate polymers with either ribitol or glycerol linked by phosphodiester bonds
Classes: (1) Lipotechoic acids
(2) Wall techoic acid
Functions:
(a) binds and regulates movement of cations in and out of the cell
(b) provides wall’s antigenic specificity
(c) may also assume a role in cell growth, preventing extensive wall breakdown and possible cell lysis

28
Q

Outer Membrane

  • G(+) or G(-)
  • function
  • contents
A

Primarily in Gram (-)
-bilayer membrane
-controls transport of certain proteins from the environment
Contents:
-surface antigens and receptors present
-Lipopolysaccharide (LPS) -consists of:
a) O-antigen polysaccharides (antigenic)
O for outer
b) water soluble core polysaccharide
c) Lipid A

29
Q

Lipid A

A

responsible for toxic properties

Gram (-) Endotoxin

30
Q

Gram (+) vs. Gram (-)

-Envelope

A 
Gram (+) -2 Layers
  1) Peptidoglycan (open, netlike)
  2) Cytoplasmic membrane (hydrophobic)
Gram (-) -3 Layers
  1) Outer membrane (hydrophobic)
  2) Peptidoglycan (open, netlike)
  3) Inner membrane (hydrophobic)
31
Q

Gram (+) vs. Gram (-)

-Unique features

A

Gram (+)
-Teichoic Acids -helps in the attachment to human cells (along with pili and specific virulence factors)

Gram (-)

- Outer membrane and endotoxin
- Pili
- Specific Virulence Factors
32
Q

Gram (+) vs. Gram (-)

-Antigens & Proteins

A

Gram (+)

 - Surface antigens- Teichoic acids
 - Surface specific proteins
   * M-protein (Streptococcus (fimbria))
   * Tuberculin (M. tuberculosis)
   * A-protein (S. aureous)

Gram (-)

 - O antigens (polysaccharide of LPS)
 - Outer membrane proteins
 - Fimbria and pili
33
Q

Gram (+) vs. Gram (-)

-Capsules and Flagella

A

Gram (+)

  • Capsular material (except S. pyogenes hyaluronic acid capsule)
  • Flagella

Gram (-)

  • Capsular material
  • Flagella
34
Q

Gram (+) vs. Gram (-)

-Peptidoglycan

A

Gram (+)
-thick layer, highly cross linked by pentaglycine bridges

Gram (-)
-thin layer, not highly cross linked

35
Q

Gram (+) vs. Gram (-)

-Susceptibility to lysozyme and beta lactam drugs

A

Gram (+)
-more susceptible

Gram (-)
-less susceptible

36
Q

Gram (+) vs. Gram (-)

-Major trigger of inflammation

A

Gram (+)
-peptidoglycan-teichoic acids

Gram (-)
-endotoxins

37
Q

4 major shapes of bacteria

A

1) Cocci: spherical
2) Bacilli: rods (short bacilli are cocco-bacilli)
3) Spiral forms: comma, S, or spiral shaped
4) Pleomorphic: lacking a distinct shape (like jello)

38
Q

Gram (+) Bacteria

A

6 classic: 2 cocci, and 4 bacilli

  • Streptococcus
  • Staphylococcus
  • Bacillus (spores)
  • Clostridium (spores)
  • Corynebacterium
  • Listeria
39
Q

Gram (-) Bacteria

A

Cocci - Neisseria
Spiral - Spirochetes
-rest are G(-) rods or pleomorphic

40
Q

Acid Fast Stain

A

1) Corbol Fuschin with heat
2) Alcohol
3) Methylene blue
*acid fast =red, non acid fast =blue
Mycobacterium ->acid fast
Nocardia ->partially acid fast
All bacteria except Legionella micadadei ->non-acid fast

41
Q

Non Gram Staining Bacteria

A

Mycoplasma -permanently lack peptidoglycan
*Diagnosis -largely clinical. 65% patients produce cryoagglutinins (agglutinate RBC’s in cold) -suggestive, not specific

Ureaplasma -does not have a cell wall

42
Q

Poorly Gram staining or poorly visible bacteria

A
  • Mycobacteria -waxy cell wall, does not take stain
  • Rickettsiae and Chlamydiae -stain color not visible (too small to be visualized)
  • Spirochetes -Treponema pallidum (syphilis) and Borrelia burgdorferi (Lyme disease) detected by dark field microscopy
43
Q

Obligate Aerobes

A

-require Oxygen for growth at atmospheric oxygen levels (21%)
-no fermentive pathways
-generally produce superoxide dismutase
(eg Pseudomonoas, M.tuberculosis, Bacillus)

44
Q

Microaerophiles

A

-require oxygen for growth, but concentration of oxygen must be below atmospheric level (<21%)
(eg Campylobacter, Helicobacter)

45
Q

Facultative Aerobes

A

-organisms will use oxygen if it is present but can grow by anaerobic respiration or fermentation in the absence of oxygen
(eg most human pathogens, Streptococci, Enterobacteria)
-Aka Facultative anaerobes

46
Q

Aerotolerant Anaerobes

A

-organisms can grow in the presence of oxygen by they cannot use it
(eg Streptococcus spp.)

47
Q

Obligate Anaerobes

A

-organism cannot grow in presence of oxygen
-utilize fermentive pathways
(eg Actinomyces, Bacteriodes, Clostridium)
(^ABC of anaerobiosis)

Microbiology (15 decks)

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