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Micro Test 2- Albertson > Control Of Microbial Growth & Tools and Techniques > Flashcards

Control Of Microbial Growth & Tools and Techniques Flashcards

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1
Q

Infections that develop during the course of a hospital stay and not present at the time of admission

A

Nosocomial infection

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2
Q

Microbes present at given place and time that are undesirable or unwanted

A

Contaminant

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3
Q

Free of all microorganisms and their spores

A

Sterile

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4
Q

Agent or method used to carry out disinfection

A

Disinfectant

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5
Q

Use of chemical agents on the skin or other living tissue to eliminate or inhibit microorganisms

A

Antisepsis

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6
Q

Use of physical procedures or chemical agents to destroy, inhibit, neutralize, or remove at least most potentially infectious microorganisms

A

Disinfect / decontaminate

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7
Q

Microbial resistance to killing (from most resistant to least resistant)

A 
Bacterial endospore 
Mycobacterium 
Protozoan cysts 
Non-enveloped small viruses 
Vegetative bacteria 
Fungi 
Enveloped viruses

(Younger cells are easier to destroy then older cells)

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8
Q

Factors affecting the effectiveness and choice of sterilization or disinfection method

A

Microbial population composition
Microbial death
Population size
Concentration/ intensity of antimicrobial
Duration of exposure
Temperature and pH
Presence of protective or neutralizing matter
Physical nature of materials being treated

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9
Q

Modes of action of microbial control methods

A

Damage to cell wall
Disrupt cytoplasmic membrane
Inhibit synthesis of proteins and nucleic acids
Alter function of proteins and nucleic acids

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10
Q

General methods of physical control of microorganisms

A

Cold temperatures
Heat
Radiation
Filtration

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11
Q

How can cold temperatures be a physical control?

A

Refrigeration
- Slow metabolism of microbes, but does not kill most microbes

Freezing
- stops metabolism, but does NOT kill microbes

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12
Q

How can heat be a physical control?

A

Heat kills the cells

Most heat is more effective than dry heat but boiling does not kill bacterial endospores

Dry heat
Most heat
Incineration

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13
Q

What are the conditions of dry heat?

A

160 to 180 C for two hours

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14
Q

What are the conditions for moist heat?

A

121 C for 15 minutes

  • minimum time required to ensure killing
  • Large load may require more then an hour
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15
Q

What are the limitations to moist heat?

A
  • cant be used for certain thermolabile substances

- cant be used for items adversely affected by moisture

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16
Q

The burning of organic material destroys living cells

A

Incineration

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17
Q

How can radiation be a physical control?

A

Ionizing radiation- Gamma
Ionizing radiation- Electron beam radiation
Non- ionizing radiation- ultraviolet

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18
Q

How can filtration be a physical control?

A

Membrane micropore filters

High-efficiency particulate air (HEPA) filtration

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19
Q

Methods of chemical control of microorganisms

A

High- level disinfectant
Intermediate- level disinfectant
Loop level disinfectant

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20
Q

What may be sterilants under appropriate conditions?

A

High- level disinfectants

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21
Q

Microbial and sporocidal, although some may do so slowly; effectiveness approaches sterilization

A

High- level disinfectants

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22
Q

Effective against vegetative forms of bacteria and maybe be effective against fungi and viruses but few products will be sporocidal

A

Intermediate- level disinfectants

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23
Q

A few are antiseptics

A

Intermediate- level disinfectants

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24
Q

Usually bactericidal; not sporocidal or tuberculocidal, often not fungicidal or virucidal

A

Low- level disinfectants

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25
A chemical substance of natural, semisynthetic, or synthetic origin that inhibits or kills microorganisms and which can be used to treat or control infection
Antibiotic
26
The antibiotic will affect only the target organism (microbe) without harming the host (patient)
Selective toxicity
27
What are inhibitors of cell wall synthesis?
Beta-lactam Antibiotics Vancomycin Bacitracin Isoniazid (INH)
28
Inhibits peptidoglycan synthesis by inhibiting the formation of cross links between the polymers of the bacterial cell wall and examples
Beta- lactam - penicillins - cephalosporins
29
Binds onto the cross-link peptide, so that the link cannot be completed and peptidoglycan polymer cannot elongate
Vancomycin
30
Blocks phospholipid carrier that helps carry subunits of peptidoglycan across membrane to cell wall
Bacitracin
31
Inhibits formation of mycolic acid in cell walls of mycobacterium (tb organism)
Isoniazid (INH)
32
Inhibitors of protein synthesis
Chloramphenicol, clindamycin Macrolides Aminoglycosides Tetracyclines
33
What is the principle of inhibitors of protein synthesis?
Inhibits accurate translation of mRNA or polypeptide chain formation at the ribosome
34
Inhibits the polypeptide elongation in translation by binding to 50S ribosome subunit and blocking peptide bond formation
Chloramphenicol, clindamycin
35
Binds to 50S subunit; prevents translocation
Macrolides
36
Inhibit translation by binding to 30S ribosomal protein causing misreading of mRNA and incomplete synthesis of protein molecules
Aminoglycosides
37
Inhibits translation into polypeptides (protiens) by blocking binding of tRNA to the 30S ribosome-mRNA complex
Tetracyclines
38
Disrupts functional integrity of cytoplasmic membrane, allowing nucleotides and proteins to escape
Principle of inhibitors of cell membrane function
39
Inhibitors of cell membrane function
Polymyxins | Amphotericin B
40
Active against gram-negatives, but neurotoxins limits them to external use
Polymyxins
41
Antifungal; binds with ergosterol in fungal membranes; somewhat toxic
Amphotericin B
42
Competitive inhibition of essential nucleic acid precursor or binds essential enzyme
Inhibitors of nucleic acid synthesis
43
Inhibitors of nucleic acid synthesis
``` Quinolone and Fluorquinolones Rifampin Metronidazole Nucleoside analogues Flucytosine, 5-fluorocytosine ```
44
Inhibit bacterial DNA gyrase
Quinolone and Fluorquinolones
45
Inhibits transcription by binding to RNA polymerase and inhibiting initiation of mRNA synthesis
Metronidazole
46
Antiviral antimicrobics
Nucleoside analogues
47
Incorporates into fungal RNA and interferes with DNA and protein synthesis
Flucytosine, 5-fluorocytosine
48
Inhibitors of bacterial metabolism
Sulfonamides Trimethoprim Azoles
49
What do antiviral inhibit?
Inhibit viral DNA polymerase | Inhibit translation of viral mRNA
50
Major types of culture media
Nutrient Enriched Selective Differential
51
To dilute the specimen in order to obtain colonies which are physically separated from each other
Isolation - streak the specimen across agar cutler media in Petri dish
52
A single type of bacteria which is maintained free from other bacteria
Pure culture | - Pure culture is required for biochemical testing
53
What is the significance of bacterial colony morphology?
Enables visual differentiation of many bacteria
54
Hemolysis is only where and due to what?
Due to bacterial production of enzymes which alter the hemoglobin of red blood cells - Alpha: green sone around colony - Beta: clear zone around colony - Gamma: no change in the red blood cells around the colony
55
Cellular morphology and staining characteristics are useful
Microscopic exam - Gram stain or various wet mount preparations
56
Grows on blood agar plate and other special media similar to bacteria and how long will it take?
Cultivation of yeast - 2 to 7 days
57
Presumptive by microscopy; biochemical tests; antigen tests
Identification for yeasts
58
Grow on media with antibiotics which inhibit the growth of bacteria and when will colonies be visible?
Cultivation for moulds - 1 to 4 weeks
59
Direct microscopic exam of specimen; microscopic exam of culture; few biochemical tests; few antigen detection tests
Identification of moulds
60
Grow in living culture cells and how long will it take to grow?
Cultivation of viruses and some atypical bacteria - 2 to 21 days to grow
61
The ability of the test to detect every low levels of antigen or antibody when it is present
Sensitivity - designed to ensure that all true- positives are detected - may be used as initial screening or presumptive tests
62
The ability of the test to accurately detect only the correct antigen or antibody
Specificity - distinguish cross- reactive and false positive results from true positives
63
Reaction is based on specific Ag-Ab match-ups, what are they?
Epitopes must be detectable Epitopes must be highly specific to produce accurate results Possibility of cross reactive (false positive)
64
Increase the number of copies of significant microbial gene sequences soothed so they can be detected
Gene amplification
65
Test kits used to detect the presence of significant gene sequences
Gene probes
66
The reaction of a particle- sized antigen with its corresponding antibody resulting in a macroscopic (visible) clumping
Slide agglutination
67
Characteristics of slide agglutination
``` Time: 2-20 min Low sensitivity Uses: - specimen screening - confirm culture/ biochemical identification ```
68
AB is tagger with fluorescent substance which hives off a particular color of light at a specified wavelength of UV light
Immunoflourescence
69
Characteristics of Immunoflourescence
Time: real time to 1 hour to 2 days after collection Ver sensitive and very specific
70
Ab (known) is labeled with color producing enzyme
Enzyme Linked Immunosorbent Assay (ELISA) Method
71
Characteristics of ELISA
- Known Ab reacts with unknown Ag; unbound Ab washed off - Very sensitive and accurate test Time: Few min-2 days; typically 1-4 hours
72
Know molecule and detection molecules are embedded in a membrane
Lateral flow immunoassay - specimen deposited on one end of membrane and wicking pad draws the fluid containing the specimen and reagents through membrane Prego test
73
What are the commonly used objectives and eyepiece magnification?
``` Low power - 10x High (dry) power - 40 to 45x Oil immersion - 90 to 100x ``` Eye piece 10x
74
Magnification total, lighting and exam for low power
Total: 100x total Lighting: use low light intensity Exam: KOH prep, other wet count preparations
75
Magnification total, lighting and exam for high dry power
Total: 450x Lighting: low to medium light Exam: other wet mount preparations
76
Magnification total, lighting and exam for oil immersion
Total: 1000x Lighting: high light intensity Exam: gram stain of bacteria
77
Gran stain smear preparation
1. Smear specimen onto clean glass 2. Allow to air dry 3. Fix smear to slide by flooding dry smear with methanol for 1 min
78
What are the staining steps of a gram stain?
1. Primary stain (crystal violet): 1 min, rinse 2. Mordant (grams iodine)L 1 min, rinse 3. Decolorizer (acetone and alcohol): 2 to 5 seconds, rinse 4. Counterstain (safranin): 30 to 60 seconds, rinse, dry
79
When is a gram stain interpreted and what do the results mean?
30-60 minutes Gram positive: blue-violet Gram negative: print-red
80
What is the procedure of wet mount microscopic exams?
1. Place specimen on clean slide and cover with think glass | 2. Observe using low and/ or high dry power and reduced light intensity
81
What are the four wet mount exams?
Potassium Hydroxide Wet Prep (KOH) - fungal mycelia fragment in skin scrapings India ink capsules in CSF - reveals yeast cells Saline we prep of vaginal exudate - reveals yeast cells and Trichomonas Direct observation Viral or chlamydia cell - reveals cytoplasmic effects (CPE)
82
The microorganism is not inhibited by the maximum safe dose/ concentration of the anti microbic
Resistant
83
The microorganism is inhibited by the maximum safe dose/ concentration of anti microbic
Susceptible
84
The microbe may be inhibited by a very high dosage that may be borderline toxic
Intermediate | -typically resistant
85
Factors affecting choice of antimicrobic
``` “Drug-bug” relationship Toxicity of drug Route of administration for pt Patient compliance Cost of treatment ```
86
What is the purpose of disk diffusion?
Determine which antibiotics might be effective in treating a particular infection when tested against one breakpoint concentration of each antimicrobic
87
What is the principle of disk diffusion?
Technique is useful only for rapid growing aerobic and facultative bacteria
88
Interpretation of disk diffusion
- zone size measured and compared | - zone size correlates with specific concentration of anti microbic in bloodstream
89
The purpose of Minimum inhibitory concentration
Determines the minimum effect concentration of each anti microbic agent that is effective against the bacterial pathogen
90
The principle of Minimum inhibitory concentration
- Bacterium is tested against various concentrations of each antimicrobic - Minimum concentration required to inhibit the bacterium is report, often along with interpretive information
91
The interpretation of Minimum inhibitory concentration
Report indicate the MIC value | - one MIC per antimicrobic for each bacterium

Micro Test 2- Albertson (3 decks)

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