Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology Prelim > Microbial Control > Flashcards

Microbial Control Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Sepsis

A

microbial contamination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Asepsis:

A

absence of significant contamination. o Aseptic surgery techniques prevent microbial contamination of wounds. o Antimicrobial chemicals, expected to destroy pathogens but not to achieve sterilization § Disinfectant: the destruction of vegetative pathogens, used on objects § Antiseptic: used on living tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Nosocomial

A

hospital infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sterilization:

A

Removal of all microbial life (heat, filtration) o For food: Commercial sterilization to kill C. botulinum endospores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Sanitization

A

reduce microbe numbers to safe levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Bacteriostatic:

A

Inhibits bacterial reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

bactericidal

A

kills bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

RATE OF MICROBIAL DEATH

A

Bacterial populations subjected to heat or antimicrobial chemicals die at a constant rate. • Microbial Death Curve, plotted logarithmically, shows this constant death rate as a straight line.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

EFFECTIVENESS OF ANTIMICROBIAL TREATMENT

A

t depends on: • Time it takes to kill a microbial population is proportional to number of microbes. • Microbial species and life cycle phases (e.g.: endospores) have different susceptibilities to physical and chemical controls. • Organic matter may interfere with heat treatments and chemical control agents. • Exposure time: Longer exposure to lower heat produces same effect as shorter time at higher heat. • Environmental influences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

ACTIONS OF MICROBIAL CONTROL AGENTS

A

• Alternation of membrane permeability • Damage to proteins • Damage to nucleic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

PHYSICAL METHODS OF MICROBIAL CONTROL

A

Not for use on living organisms Somehow, alter membrane permeability and/or structure of proteins and nucleic acids Heat is very effective (fast and cheap).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thermal death point (TDP):

A

The lowest temperature at which all cells in the culture are killed in 10 min.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thermal death time (TDT):

A

Time to kill all cells in a culture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Decimal Reduction Time (DRT):

A

Minutes to kill 90% of a population at a given temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

MOIST HEAT STERILIZATION

A

Denatures proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Autoclave

A

Steam under pressure Most dependable sterilization method • Steam must directly contact material to be sterilized. • Pressurized steam reaches higher temperatures. • Normal autoclave conditions: 121.5 OC for 15 min. • Prion destruction: 132 OC for 4.5 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

PASTEURIZATION

A

Significant number reduction (esp. spoilage and pathogenic organisms) it does not sterilize!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The historical goal of pasteurization

A

the destruction of M. tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Classic holding method: (pasteurization)

A

63 OC for 30 min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Flash pasteurization (HTST):

A

72 OC for 15 sec. o Most common in the US o Thermoduric organisms survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Ultra-High Temperature (UHT):

A

140 OC for < 1 sec o Technically not pasteurization because it sterilizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

DRY HEAT STERILIZATION

A

• Kills by sterilization • Flaming of loop • Incineration of carcasses o Anthrax o Foot and mouth disease o Bird flu

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

FILTRATION

A

Air filtration using high efficiency particulate air (HEPA) filters. Effective to 0.3 µm Membrane filters for fluids. • Pore size for bacteria: 0.2 – 0.4 µm • Pore size for viruses: 0.01 µm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

LOW TEMPERATURE

A

• Slows enzymatic reactions à inhibits microbial growth • Freezing forms ice crystals that damage microbial cells • Refrigeration (deep freezing, lyophilization)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

High pressure in liquids

A

denatures bacterial proteins and preserves flavor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Desiccation

A

prevents metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Osmotic pressure

A

causes plasmolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

IONIZING RADIATION

A

• X-rays, gamma rays, electron beams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What element is most commonly used in Ionizing radiation

A

Commonly used Cobalt-60 radioisotope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

bacteria that are sensitive to ionizing radiation

A

Salmonella and pseudomonas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

UV Light

A

Most effective wavelength ~ 260 nm • Effect: thymine dimers • Actively dividing organisms are more sensitive because thymine dimers cause ____? • Used to limit air and surface contamination. Use at close range to directly exposed microorganisms E.g.: germicidal lamps in OR, cafeteria, and our lab

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

MICROWAVE

A

Wavelength: 1 mm - 1m • H2O quickly absorbs energy released as heat to environment • Indirect killing of bacteria through heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

CHEMICAL METHODS OF MICROBIAL CONTROL

A

• Few chemical agents achieve sterility. • Consider the presence of organic matter, degree of contact with microorganisms, and temperature • Disinfectants regulated by EPA • Antiseptics regulated by FDA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

USE-DILUTION TEST

A
  1. Metal rings dipped in test bacteria are dried. 2. Dried cultures of S. choleraesuis, S. aureus, and P. aeruginosa are placed in disinfectant for 10 min at 20°C 3. Rings are transferred to culture media to determine whether bacteria survived treatment.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

DISK-DIFFUSION METHOD

A

The disk of filter paper is soaked with a chemical and placed on an inoculated agar plate; a zone of inhibition indicates effectiveness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

PHENOL =

A

carbolic acid (historic importance) • Phenolics: Cresols (Lysol); disinfectant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

BISPHENOLS

A

• Hexachlorophene (pHisoHex, prescription), hospitals, surgeries, nurseries • Triclosan (toothpaste, antibacterial soaps, etc).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

CHLORINE

A

• Oxidizing agent • Widely used as a disinfectant • Forms bleach (hypochlorous acid) when added to water. • Broad spectrum, not sporicidal (pools, drinking water)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

IODINE

A

• More reactive, more germicidal • Alters protein synthesis and membranes. • Tincture of iodine (solution with alcohol) à wound antiseptic • Iodophors combined with an organic molecule o iodine detergent complex (e.g. Betadine®). Occasional skin sensitivity, partially inactivated by organic debris, poor sporicidal activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Ethyl (60 - 80% solutions) and isopropyl alcohol

A

• Denature proteins, dissolve lipids • No activity against spores and poorly effective against viruses and fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

MERCURIC CHLORIDE

A

(HgCl2, Greeks & Romans for skin lesions); Thimerosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

COPPER

A

against chlorophyll-containing organisms à Algicides

43
Q

SILVER NITRATE (AGNO3):

A

Antiseptic for eyes of newborns

44
Q

ZINC (ZNCL2)

A

in mouthwashes, ZnO in antifungal In paint

45
Q

SURFACE ACTING INGREDIENTS/SURFACTANTS

A

soaps and detergents

46
Q

The major purpose of soap:

A

Mechanical removal and use as wetting agent

47
Q

Acidic-

A

Anionic detergents: Anion reacts with the plasma membrane. Nontoxic, non-corrosive, and fast-acting. Laundry soap, dairy industry.

48
Q

Cationic detergents

A

Quaternary ammonium compounds (Quats). Strongly bactericidal against a wide range, but especially Gram (+) bacteria

49
Q

SULFUR DIOXIDE:

A

wine

50
Q

ORGANIC ACIDS:

A

Sorbic acid, benzoic acid, and calcium propionate; Inhibit metabolism; Control molds and bacteria in foods and cosmetics

51
Q

SODIUM NITRATE AND NITRITE:

A

prevents endospore germination; In meats; Conversion to nitrosamine (carcinogenic)

52
Q

ALDEHYDES (alkylating agents)

A

• Inactivate proteins by cross-linking with functional groups (-NH2, -OH, -COOH, -SH)

53
Q

Glutaraldehyde:

A

sterilant for delicate surgical instruments (Kills S. aureus in 5, M. tuberculosis in 10 min)

54
Q

Formaldehyde:

A

Virus inactivation for vaccines

55
Q

CHEMICAL STERILANTS

A

for heat sensitive material • Denature proteins • Ethylene oxide

56
Q

PLASMA

A

• Luminous gas with free radicals that destroy microbes • Use: Tubular instruments, hands, etc

57
Q

HYDROGEN PEROXIDE:

A

OXIDIZING AGENT • Inactivated by catalase à Not good for open wounds Esp. effective against anaerobic bacteria • Effervescent action may be useful for wound cleansing through the removal of tissue debris

58
Q

Resistance order

A

Prions bacterial endospores Mycobacteria protozoa cyst g -ve bacterium Fungal spores virus without envelope gram +ve Virus with lipid

59
Q

STERILIZATION

A
  • The killing or removal of all viable organisms within a growth medium
60
Q

INHIBITION

A
  • Effectively limiting microbial growth.
61
Q

DECONTAMINATION

A
  • The treatment of an object to make it safe to handle.
62
Q

DISINFECTION

A
  • Directly targets the removal of all p
63
Q

HEAT STERILIZATION

A
  • Is the most widely used method of controlling microbial growth - Simplest means of sterilizing materials provided the material is itself resistant to heat.
64
Q

Decimal reduction time

A

Amount of time required to reduce the viability tenfold

65
Q

Antimicrobial agents can be classified as

A

bacteriostatic, bacteriocidal and bacteriolytic

66
Q

MINIMUM INHIBITORY CONCENTRATION (MIC)

A

Is the smallest amount of an agent needed to inhibit the growth of a microorganism - Varies with the organism used, inoculum size, temp, pH, etc.

67
Q

DISC DIFFUSION ASSAY

A

The antimicrobial agent added to the filter paper disc The antimicrobial agent added to the filter paper disc - MIC is reached at some distance § Zone of Inhibition – an area of no growth around the disc.

68
Q

Antimicrobial drugs are classified on the basis of

A
  • Molecular structure - Mechanism of action - Spectrum of antimicrobial activity
69
Q

Characteristics of the ideal antimicrobial drug:

A

Selectively toxic to the microbe but nontoxic to host cells - Microbicidal rather than microbiostatic - Relatively soluble and function even when it is highly diluted in body fluids - Remains potent long enough to act and is not broken down or excreted prematurely - Not subject to the development of antimicrobial resistance - Complements or assists the activities of the host’s defences - Remains active in tissues and body fluids - Readily delivered to site of infection - Not excessive in cost - Does not disrupt the host’s health bu causing allergies of predisposing the host to other infections.

70
Q

Inhibition of cell wall synthesis

A

Pencillin, Cephalosporins

71
Q

Beta-Lactam drugs

A

selective inhibitors of bacterial cell wall synthesis

72
Q

Inhibition/alteration of cell membrane function

A

Detergents disrupt cytoplasmic membrane o Ex. Valinomycin, Daptomycin, Telavancin

73
Q

Inhibition of protein synthesis:

A

Bacteria have 70S ribosomes while mammalian cells have 80 S ribosomes, which explains why antimicrobials can inhibit protein synthesis in bacterial ribosomes without having a major effect on mammalian ribosomes Ex. aminoglycosides, Macrolides, Azalides and Ketolids, Lincosamides, tetracyclines, Glycylcyclines, Chloramphenicol, Streptogramins, Oxazolidinones

74
Q

Inhibition of Nucleic acid synthesis:

A

on of Nucleic acid synthesis: o Inhibiting growth by binding strongly to DNA-Dependent RNA polymerase of bacteria and inhibits RNA synthesis. (Rifampicin) o Inhibit microbial DNA synthesis by clocking DNA gyrases (Quinilones and fluoroquinolones) o Sulfonamides enter into reaction and compete for active center of enzyme. o More examples: Trimethoprim and Timetrexate

75
Q

SULFA DRUGS:

A

discovered by Gerhard Domagk in the 1930’s\Inhibit growth of bacteria (sulfanilamide is the simplest) - Isoniazid is a growth analog effective only against Mycobacterium.

76
Q

NUCLEIC ACID-BASE ANALOGS:

A

formed by adding bromine or fluorine

77
Q

QUINOLONES:

A

antibacterial compounds that interfere with DNA gyrase (e.g., ciprofloxacin)

78
Q

Gram Negatives and positives

A

vary in their sensitivities to antibiotics but Broad spectrum antibiotics are effective against both groups.

79
Q

B-lactam antibiotics are

A

one of the most important groups of antibiotics of all time and over half of all antibiotics used worldwide. Composed of Penicillins, Cephalosporins & Cephamycins.

80
Q

Penicillin

A

Discovered by Alexander Fleming - Effective against Gram-positive, but some synthetic forms can act against gram-negative bacteria - Targets the cell wall synthesis - Natural: Benzylpenicillin (Penicillin G)

81
Q

Methicillin

A

(acid-stable)

82
Q

Oxacillin

A

(acid-stable)

83
Q

Ampicillin

A

(broad spectrum & acid stable)

84
Q

Carbenicillin

A

(broad spectrum & acid stable)

85
Q

CEPHALOSPORINS

A
  • Produced by fungus Cephalosporium - Targets cell wall synthesis - Treats Gonorrhoea
86
Q

Daptomycin

A

produced by streptomyces- g+ve infection

87
Q

Platensimycin

A

New antibiotic, BS, MRSA and vancomycin-resistant Enterococci

88
Q

Aminoglycoside

A

Kanamycin, neomycin, amikacin

89
Q

Macrolides

A

Erythromycin- lactone rings bonded to sugars

90
Q

Tetracyclines

A

30S inhibition, BS, Used in Humans and animals, aureomycin, Terramycin

91
Q

AZT-

A

block Reverse Transcriptase DNA

92
Q

NNTRI

A

Bind directly to RT and inhibit reverse transcription

93
Q

FUSION INHIBITORS

A

prevent viruses from successfully fusing with the host cell

94
Q

Two categories of drugs successfully limit influenza infection:

A
  • ADAMANTANES - NEURAMINIDASE INHIBITORS
95
Q

Interferons

A

are small proteins that prevent viral multiplication by stimulating antiviral proteins in uninfected cells

96
Q

Mechanism of drug resistance:

A
  • Drug inactivated by Penicillinases - Decreased permeability to drug or increased elimination of drug from cell. - Change in metabolic patterns - Change in drug receptors
97
Q

Methicillin-resistant S. aureus

A

(MRSA)

98
Q

Origin of drug resistance:

A

Nongenetic origin of drug resistance o Microorganisms that are metabolically inactive may be phenotypically resistant to drugs, but their offspring are fully susceptible. Ex. Mycobacteria o Lose specific target structure for drug for several generations and may become resistant. Ex. Penicillin-susceptible organisms may change to cell wall deficient L forms o Microorganisms may infect host at sites where antimicrobials are excluded or not active. Ex. gentamycin not effective against Salmonella enteric fevers because they are found intracellularly and Gentamycin do not enter the cells.

99
Q

The genetic origin of drug resistance

A

Result of change and subsequent selection process

100
Q

Chromosomal Resistance

A

Result of spontaneous mutation

101
Q

Cross-resistance

A

o Microorganisms resistant to a certain drugs may also be resistant to other drugs that share a mechanism of action.

102
Q

Limitation of drug resistance:

A
  • By maintaining high levels of drugs in tissues to inhibit both the original population and first-step mutants - Spontaneously administering two drugs that do not give cross-resistance - Avoiding exposure of microorganisms to a particularly valuable drug by limiting its use.
103
Q

Bacteriophage therapy

A
  • Use of bacteriophages to treat infections - A form of the virus that attacks bacteria

Microbiology Prelim (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions