Control of Microorganisms

1742 days ago, 780 views
PowerPoint PPT Presentation
Definitions. Cleansing: A treatment that murders or evacuates every single living cell, including infections and spores, from a substance or objectDisinfection: A treatment that diminishes the aggregate number of microorganisms on an article or surface, yet does not as a matter of course uproot or execute the majority of the organisms. Definitions.

Presentation Transcript

Slide 1

Control of Microorganisms Definitions Conditions Influencing Antimicrobial Activity Physical Methods Chemical Agents Preservation of Microbial Cultures

Slide 2

Definitions Sterilization: A treatment that executes or evacuates every living cell, including infections and spores, from a substance or protest Disinfection: A treatment that decreases the aggregate number of organisms on a question or surface, however does not really expel or murder the greater part of the microorganisms

Slide 3

Definitions Sanitation: Reduction of the microbial populace to levels considered safe by general wellbeing benchmarks Antiseptic: A mellow disinfectant operator reasonable for use on skin surfaces - cidal: A postfix implying that "the specialist slaughters." For instance, a bacteriocidal specialist eliminates microscopic organisms

Slide 4

Definitions - static: An addition that signifies "the specialist hinders development." For instance, a fungistatic operator represses the development of growths, yet doesn't really execute it.

Slide 5

Conditions Influencing Antimicrobial Activity Under most conditions, a microbial populace is not killed in a flash by an operator but rather over a timeframe The passing of the populace after some time is exponential, like the development amid log stage

Slide 6

Conditions Influencing Antimicrobial Activity Several basic elements assume enter parts in deciding the viability of an antimicrobial specialist, including: Population estimate Types of life forms Concentration of the antimicrobial specialist Duration of introduction Temperature pH Organic matter Biofilm arrangement

Slide 7

Physical Methods Moist Heat Dry Heat Low Temperatures Filtration Radiation

Slide 8

Physical Methods: Moist Heat Mechanism of killing is a combinantion of protein/nucleic corrosive denaturation and film disturbance Effectiveness Heavily reliant on kind of cells present and in addition ecological conditions (sort of medium or substrate) Bacterial spores considerably more hard to kill than vegetative cells

Slide 9

Physical Methods: Moist Heat Measurements of killing by soggy warmth Thermal demise point (TDP): Lowest temperature at which a microbial suspension is killed in 10 minutes; deluding on the grounds that it suggests quick lethality in spite of substrate conditions Thermal demise time (TDT): Shortest time expected to kill all life forms in a suspension at a predetermined temperature under particular conditions; deceiving in light of the fact that it doesn't represent the logarithmic way of the passing bend (hypothetically impractical to get down to zero)

Slide 10

Physical Methods: Moist Heat Measurements of killing by wet warmth (cont.) Decimal diminishment time ( D esteem): The time required to decreased a populace of microorganisms by 90% (a 10-overlap, or one decimal, lessening) at a predefined temperature and indicated conditions z esteem: The adjustment in temperature, in ºC, important to bring about a ten times change in the D estimation of a living being under determined conditions F esteem: The time in minutes at a particular temperature (typically 121.1°C or 250 °F) expected to kill a populace of cells or spores

Slide 11

Physical Methods: Moist Heat Calculations utilizing D and z values Given: For Clostridium botulinum spores suspended in phosphate cushion, D 121 = 0.204 min How long would it take to decrease a populace of C. botulinum spores in phosphate cushion from 10 12 spores to 10 0 spores (1 spore) at 121°C? Reply: Since 10 12 to 10 0 is 12 decimal decreases, then the time required is 12 x 0.204 min = 2.45 min

Slide 12

Physical Methods: Moist Heat Calculations utilizing D and z values (cont.) Given the D esteem at one temperature and the z esteem, we can infer a condition to anticipate the D esteem at an alternate temperature:

Slide 13

Physical Methods: Moist Heat Calculations utilizing D and z values (cont.) First, compose a condition for this line. Since the y pivot is on a log scale, then y = log (D). The slant of the line is - 1/z; we'll let the y block be equivalent to c. In this way: At a given temperature T a , D = D a , so we can dispose of the "c" term

Slide 14

Physical Methods: Moist Heat Calculations utilizing D and z values (cont.) We can unequivocally allude to the second temperature and D esteem as T b and D b , so:

Slide 15

Physical Methods: Moist Heat Calculations utilizing D and z values (cont.) Given: For Clostridium botulinum spores suspended in phosphate support, D 121 = 0.204 min and z = 10°C How long would it take to lessen a populace of C. botulinum spores in phosphate cradle from 10 12 spores to 10 0 spores (1 spore) at 111°C? Reply: To answer the question we have to know D 111 , which we can figure from the recipe : log( D 111/0.204) = (121-111)/10 D 111 = 0.204(10) = 2.04 min 12 D 111 = 24.5 min

Slide 16

Physical Methods: Moist Heat Calculations utilizing D and z values (cont.) Given: For Staph. aureus in turkey stuffing, D 60 = 15.4 min and z = 6.8°C How long would it take to decrease a populace of Staph. aureus in turkey stuffing from 10 5 cells to 10 0 cells at 55°C, 60°C, and 65°C? Answers: Work it out for yourself. Here are the appropriate responses. At 55°C: 419 min At 60°C: 77 min At 65°C: 14.2 min

Slide 17

Physical Methods: Moist Heat Methods of Moist Heat Boiling at 100°C Effective against most vegetative cells; insufficient against spores; inadmissible for warmth touchy chemicals & numerous sustenances Autoclaving/weight canning Temperatures over 100°C accomplished by steam weight Most methodology utilize 121.1°C, accomplished at approx. 15 psi weight, with 15 - 30 min autoclave time to guarantee disinfection Sterilization in autoclave in biomedical or clinical research facility should by intermittently approved by testing with spores of Clostridium or Bacillus stearothermophilus

Slide 18

Physical Methods: Moist Heat Methods of Moist Heat Pasteurization Used to lessen microbial numbers in drain and different refreshments while holding flavor and sustenance nature of the drink Retards waste however does not sanitize Traditional treatment of drain, 63°C for 30 min Flash sanitization (high-temperature here and now purification); snappy warming to around 72°C for 15 sec, then fast cooling

Slide 19

Physical Methods: Moist Heat Methods of Moist Heat Ultrahigh-temperature (UHT) cleansing Milk and comparable items warmed to 140 - 150°C for 1 - 3 sec Very rapidly disinfects the drain while keeping its flavor & quality Used to deliver the bundled "rack drain" that does not require refrigeration

Slide 20

Physical Methods: Dry Heat Incineration Burner flares Electric circle incinerators Air incinerators utilized with ferementers; by and large worked at 500°C Oven cleansing Used for dry china & warm safe metal gear Typically 2 hr at 160°C is required to eliminate bacterial spores by dry warmth: this does exclude the ideal opportunity for the glass to achieve the required temp (entrance time) nor does it incorporate the cooling time

Slide 21

Physical Methods: Low Temperatures Refrigerator: around 4°C restrains development of mesophiles or thermophiles; psychrophiles will develop Freezer: "customary" cooler around - 10 to - 20°C "ultracold" lab cooler regularly - 80°C Generally hinders all development; numerous microorganisms and different organisms may survive solidifying temperatures

Slide 22

Physical Methods: Filtration Used for physically expelling organisms and tidy particles from arrangements and gasses; frequently used to clean warmth touchy arrangements or to give a disinfected wind current Depth channels: eg. Diatomaceous earth, unglazed porcelean Membrane channels: eg. Nitrocellulose, nylon, polyvinylidene difluoride HEPA channels: High productivity particulate air channels utilized as a part of laminar stream natural wellbeing cupboards

Slide 23

Physical Methods: Radiation Ultraviolet Radiation DNA retains bright radiation at 260 nm wavelength This causes harm to DNA as thymine dimer transformations Useful for persistent cleansing of work surfaces, e.g. in natural security cupboards

Slide 24

Physical Methods: Radiation Ionizing Radiation Gamma radiation created by Cobalt-60 source Powerful disinfecting specialist; enters and harms both DNA and protein; successful against both vegetative cells and spores Often utilized for sanitizing expendable plastic labware, e.g. petri dishes; and additionally anti-toxins, hormones, sutures, and other warmth touchy materials Also can be utilized for sanitization of nourishment; has been endorsed however has not been generally received by the sustenance business

Slide 25

Chemical Agents Phenolics Alcohols Halogens Heavy metals Quaternary Ammonium Compounds Aldehydes Sterilizing Gasses Evaluating Effectiveness of Chemical Agents

Slide 26

Chemical Agents: Phenolics Aromatic natural mixes with appended - OH Denature protein & upset layers Phenol, orthocresol, orthophenylphenol, hexachlorophene Commonly utilized as disinfectants (e.g. "Lysol"); are tuberculocidal, compelling in nearness of natural matter, stay on surfaces long after application Disagreeable smell & skin disturbance; hexachlorophene once utilized as a germ-free however its utilization is constrained as it causes cerebrum harm

Slide 27

Chemical Agents: Alcohols Ethanol; isopropanol; utilized at focuses between 70 – 95% Denature proteins; upset layers Kills vegetative cells of microorganisms & parasites yet not spores Used in cleaning surfaces; thermometers; "ethanol-flaring" method used to sanitize glass plate spreaders or dismembering instruments at the lab seat

Slide 28

Chemical Agents: Halogens Act as oxidizing specialists; oxidize proteins & other cell parts Chlorine mixes Used in purifying municiple water supplies (as sodium hypochlorite, calcium hypochlorite, or chlorine gas) Sodium Hypochlorite (Chlorine Bleach) utilized at 10 - 20% weakening as benchtop disinfectant Halazone tablets (parasulfone dichloroamidobenzoic corrosive) utilized by campers to sterilize water for drinking

Slide 29

Chemical Agents: