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Principles of Infectious Disease > Clinical Microbiology > Flashcards

Clinical Microbiology Flashcards

1
Q

Binary Fission

A

form of asexual reproduction and cell division

used by most bacteria

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2
Q

Generation time

A

length of time required for a single bacterial cell to yield two
daughter cells

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3
Q

Lag phase

A

active metabolism of the cells as they acquire various essential constituents prior to
division

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4
Q

Log Phase

A

Binary fission of the young cells results in an exponential increase in numbers

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5
Q

Stationary Phase

A

growth ceases as
nutrients are depleted and toxic metabolites accumulate in the medium.

No net increase in bacterial number.

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6
Q

Decline Phase

A

Old cells die rapidly followed by younger

resulting rate of
cell death is exponential

involution forms can be seen

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7
Q

involution forms

A

abnormally shaped cells

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8
Q

Direct physical measurement of cell mass

A

dry weight, wet weight, or volume of cells after centrifugation

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9
Q

Direct chemical measurement of cell mass

A

some chemical component of the cells such as total protein, or total DNA content

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10
Q

Indirect measurement of chemical activity

A

rate of O2 production or consumption, CO2 production or consumption, etc

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11
Q

Turbidity measurements of cell mass

A

amount of light scattered by a suspension of cells

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12
Q

Counting cells using a Direct smear (Breed’s method)

A

Microscopic counting of cells on a fixed and stained smear prepared from a defined volume of fluid

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13
Q

Counting cells using a counting chamber

A

Microscopic counting on a fixed volume of bacterial suspension using a calibrated slide

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14
Q

Real-Time PCR method for cell counting

A

number of bacterial cells in a sample is quantified based on detection of DNA concentration

For detection of total viable cells

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15
Q

chemoheterotrophs

A

bacteria that use organice chemicals as sources of energy production

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16
Q

fermentation

A

metabolic process that:

1) releases energy from a sugar or other organic molecules
2) does not require oxygen or an electron transport system
2a. uses an organic molecule as the final electron acceptor

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17
Q

Peptones

A

short chains of amino acid monomers linked by peptide (amide) bonds

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18
Q

Phosphates

A

essential for production of nucleic acids and molecules containing energy-rich bonds

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19
Q

Sulfates

A

are required for synthesis of sulfur-containing amino acids

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20
Q

Trace Elements

A

dietary element needed in very minute quantities for proper growth, development, and physiology

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21
Q

Growth factors

A

essential substances required in small amounts to fulfill specific roles in biosynthesis

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22
Q

Purines and pyrimidines (growth factors) required for…

A

synthesis of nucleic acids

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23
Q

Amino Acids (growth factors) required for…

A

synthesis of proteins

24
Q

Vitamins (growth factor) needed as…..

A

coenzymes and functional groups of enzymes

25
Q

General Purpose Medium

A

provides enough nutrients to allow for a wide variety of microorganisms to grow

26
Q

Bile Salts

A

inhibit most gram-positive bacteria

27
Q

Crystal Violet Dye

A

inhibits certain gram-positive bacteria

28
Q

Neutral Red Dye

A

stains microbes fermenting lactose

29
Q

Mesophils

A

Organisms with an optimum growth temperature near 37 degrees Celsius (body temperature of warm-blooded animals)

30
Q

Thermophils

A

organisms with an optimal growth temperature between 45 and 70 degrees Celsius

31
Q

Hyperthermophiles / extreme thermophils

A

optimum growth temperature between 80 and 115 degrees Celsius

32
Q

psychrophiles

A

cold loving organisms

ability to grow at 0 degrees Celsius
10-15 optimum

33
Q

psychrotrophs

A

optimum temperature near room temp but can grow at 0 degrees Celsus

34
Q

acidophiles

A

grow at an optimum pH well below neutrality (7.0)

35
Q

neutrophiles

A

grow best at a neutral pH

36
Q

alkaliphiles

A

grow best under alkaline conditions

37
Q

Buffers (in medium)

A

used to maintain pH of medium at optimal for growth despite bacterial waste
products accumulating

38
Q

Protoplast

A

bacteria whose cell wall has been completely or partially removed using either mechanical or enzymatic means

39
Q

obligate aerobes

A

require oxygen for growth

40
Q

Obligate anaerobes

A

do not need or use oxygen as it is toxic to them

41
Q

Facultative anaerobes

A

can switch between aerobic and anaerobic types of metabolism

42
Q

Aerotolerant anaerobes

A

exclusively anaerobic but are insensitive to oxygen

43
Q

Capnophiles

A

grow best in carbon dioxide

44
Q

Substrate level phosphorylation (SLP)

A

ATP synthesized during the conversion of an organic molecule from one form to another

45
Q

Electron Transport Phosphorylation (ETP)

A

ATP synthesized by dumbing electrons down transport chain

46
Q

Main nutritional requirements for bacteria

A

Organic Compounds:
C, O, N, H, P

Growth Factors:
Purines & Pyrimidines - for nucleic acids
Amino Acids - for protein synthesis
Vitamins - as coenzymes and functional groups

47
Q

___________ is a general purpose medium used for a wide range of applications including; culture storage, enumeration (counting), isolation of pure cultures or simply general culture

A

Trypticase soy agar (TSA)

48
Q

____________ is a general purpose enriched medium often used to:

  • grow fastidious organisms
  • identify hemolytic bacteria
A

Blood Agar

49
Q

_______________ is designed to grow Gram-negative bacteria and differentiate lactose fermenters from non-fermenters.

A

MacConkey agar

50
Q

Presence of a red/pink color in MacConkey agar indicate what has happened?

A

Lactose has been fermented producing acid that lowers pH of medium to produce red/ pink colored colonies

51
Q

What does MacConkey agar contain and why is it used?

A

bile salts and crystal violet dye
- to inhibit most Gram-positive bacteria
crystal violet dye
neutral red dye
- stains microbes fermenting lactose
lactose and peptone as food source

52
Q

Describe the 4 basic steps in gram staining.

A

1) Primary stain (crystal violet)
- stains gram + and - cells

2) Mordant (Gram’s Iodine)
- forms complexes with primary stain and fixes it to cells

3) Decolorizer (alcohol or acetone)
- destroys gram negative membrane and washes away primary stain
- large peptidoglycan layer of gram positive keeps primary stain in

4) Counterstaining
- safranin or basic fuchsin stains gram negative only

53
Q

Environmental factors that influence bacterial growth.

A 
– Temperature
– pH (H+ concentration)
– Moisture
– Atmospheric composition
– Osmotic pressure
54
Q

Testing for antibiotic sensitivity is often done by the _____________, where mall wafers containing antibiotics are placed onto a plate upon which bacteria are growing. If the bacteria are sensitive to the antibiotic, a clear ring, or zone of inhibition, is seen around the wafer indicating poor growth.

A

Kirby-Bauer method

55
Q

Minimum Inhibitory Concentration (MICs) can be determined by _________ or ____________, usually following the guidelines of a reference.

A

agar dilution

broth microdilution

56
Q

minimum inhibitory concentration (MIC)

A

the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation

Principles of Infectious Disease (4 decks)

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