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Control of Microbial Growth

Control of Microbial Growth. Pathogenic Microorganisms. Prions—proteins (Kuru, CJD) Viruses—DNA or RNA surrounded by a protein coat (AIDS, Herpes, Small Pox, Polio) Bacteria—unicellular organisms, genetic material not enclosed in a nuclear membrane, cell wall (Tuberculosis, Anthrax ).

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Control of Microbial Growth

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  1. Control of Microbial Growth

  2. Pathogenic Microorganisms • Prions—proteins (Kuru, CJD) • Viruses—DNA or RNA surrounded by a protein coat (AIDS, Herpes, Small Pox, Polio) • Bacteria—unicellular organisms, genetic material not enclosed in a nuclear membrane, cell wall (Tuberculosis, Anthrax)

  3. Pathogenic Microorganisms • Fungi—unicellular/multi cellular organisms with a nuclear membrane surrounding the genetic materials (Athlete’s foot, Ring worm) • Protozoa—single-celled organisms with membrane bound organelles, nucleus, no cell wall, classified by locomotion (Malaria, Cryptosporidiosis)

  4. Yersinia pestis - Gram (-) bacillus Vectors - Rat and Flea

  5. Smallpox Variola virus Eradicated in 1977 (Somalia)

  6. Control of microbial growth : introduction • Early civilizations practiced salting, smoking, pickling, drying, and exposure of food and clothing to sunlight to control microbial growth. • Use of spices in cooking was to mask taste of spoiled food. Some spices prevented spoilage. • In mid 1800s Semmelweiss and Lister helped developed aseptictechniques to prevent contamination of surgical wounds. Before then: • Nosocomial infections caused death in 10% of surgeries. • Up to 25% mothers delivering in hospitals died due to infection

  7. Control of microbial growth : introduction Sterilization: Killing or removing all forms of microbial life (including endospores) in a material or an object. Heating is the most commonly used method of sterilization. Commercial Sterilization: Heat treatment that kills endospores of Clostridium botulinum the causative agent of botulism, in canned food. Does not kill endospores of thermophiles, which are not pathogens and may grow at temperatures above 45oC.

  8. Physical Methods of Microbial Control • 1. Heat • works by denaturing enzymes and proteins

  9. Moist Heat • Kills microorganisms by coagulating their proteins. In general, moist heat is much more effective than dry heat.

  10. Moist Heat • 1. Boiling Water, Heat to 100oC or more. • kills vegetative bacterial cells, Fungi and many viruses in 10 minutes • not effective for endospores and some viruses • Hepatitis (20 min) • Some spores may survive boiling water for up to 20 hrs

  11. Moist Heat • 2. Autoclave (Chamber which is filled with hot steam under pressure. Preferred method of sterilization, unless material is damaged by heat, moisture, or high pressure) • Temperature of steam reaches 121oC at twice atmospheric pressure. • All organisms and endospores are killed within 15 minutes. • 121 C for 15 min.

  12. Autoclave • Mekanisme membunuh mikroorganisme dengan denaturasi protein dan reaksi hidrolisis • Suhu sterilisasi 121 derajat celsius 15 menit atau 134 derajat celsius 3 menit, atau 115 derajat celsius 30 menit. • Penggunaan sangat luas, peralatan bedah, diagnostik, wadah, aqua injeksi, preparat mata, cairan irigasi, media dan bahan termostabil lain

  13. Dry Heat, Kills by oxidationeffects. • Direct Flaming, Used to sterilize inoculating loops and needles. Heat metal until it has a red glow. Inoculating Loop and Needle 100% effective • Incineration, Effective way to sterilize disposable items (paper cups, dressings) and biological waste. • Hot Air Sterilization, Place objects in an oven. Require 2 hours at 170oC for sterilization, used on substances that would be damaged by moist heat sterilization (gauzes, dressings or powders)

  14. Dry heat

  15. Filtration • Removes microorganisms from solutions that might be damaged by heat, by passage of a liquid or gas through a screen like material with small pores. • culture media • enzymes • vaccines • antibiotics

  16. Filtration • High Efficiency Particulate Air Filters (HEPA): Used in operating rooms and burn units to remove bacteria from air. • Membrane Filters: Uniform pore size. Used in industry and research. Different sizes: • 0.22 and 0.45um Pores: Used to filter most bacteria. Don’t retain spirochetes, mycoplasmas and viruses. • 0.01 um Pores: Retain all viruses and some large proteins.

  17. Low Temperature: Effect depends on microbe and treatment applied. • Refrigeration: Temperatures from 0 to 7oC. Bacteriostaticeffect. Reduces metabolic rate of most microbes so they cannot reproduce or produce toxins. • Freezing: Temperatures below 0oC. • Flash Freezing: Does not kill most microbes. • Slow Freezing: More harmful because ice crystals disrupt cell structure. • Over a third of vegetative bacteria may survive 1 year. • Most parasites are killed by a few days of freezing.

  18. Dessication • In the absence of water, microbes cannot grow or reproduce, but some may remain viable for years. After water becomes available, they start growing again. Susceptibility to dessication varies widely: Neisseria gonnorrhea: Only survives about one hour. Mycobacterium tuberculosis: May survive several months. Viruses are fairly resistant to dessication. Clostridium spp. and Bacillus spp.: May survive decades.

  19. Osmotic Pressure • The use of high concentrations of salts and sugars in foods is used to increase the osmotic pressure and create a hypertonic environment. Plasmolysis: As water leaves the cell, plasma membrane shrinks away from cell wall. Cell may not die, but usually stops growing. • Yeasts and molds: More resistant to high osmotic pressures. • Staphylococci spp. that live on skin are fairly resistant to high osmotic pressure.

  20. Radiation • 1. Ionizing Radiation • gamma rays & x-rays, penetrates most substances • Used on substances that could be damaged by heat plastic petri dishes, plastic syringes, catheters, surgical gloves • Cause mutations in DNA and produce peroxides. • Disadvantages: Penetrates human tissues. May cause genetic mutations in humans.

  21. Forms of Radiation

  22. Radiation • 2. Non-Ionizing Radiation • UV Light, Wavelength is longer than 1 nanometer. Damages DNA by producing thymine dimers, which cause mutations. does not penetrate plastic, glass or proteinaceous matter • Used to reduce microbial populations • hospital rooms, nurseries, operating rooms Disadvantages: Damages skin, eyes. Doesn’t penetrate paper, glass, and cloth.

  23. Efficiency of Different Chemical Antimicrobial Agents

  24. Produk farmasetikal dan peralatan sterilisasi Ada jaminan betul-betul steril ???

  25. KONTROL STERILISASI FISIKA : thermocouple, ukuran pore KIMIA: kemampuan panas, uap atau sterilan untuk mengubah sifak fisik/kimia senyawa kimia BIOLOGI: menggunakan mikroorganisme

  26. Indikator Kimia Autoclave/dry heat larutan berwarna Browne’s tube sensitif dengan suhu Etilen oksida senyawa kimia reaktif Kertas indikator diimpregnasi senyawa kimia Radiasi Radiokromik Plastik radiosensitif yang berubah warna jika dosis rendah Dosimeter Feri ammonium sulfat atau serium sulfat

  27. Misal

  28. Indikator biologi Autoclave Bacillus stearothermophlus Clostridium sporogenes Dry heat Bacillus subtilis var niger Etilen oksida Bacillus subtilis var niger Filtrasi Serratia marcescens

  29. Direct inoculation Membrane filter

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