1. Practical bacteriology Lab -1-
Dr. Raz Nawzad

2. BACTERIA:
Bacteria are the smallest and most versatile independently living cells about (1 to 10  μm).
Prokaryotic design includes envelope, appendages, cytosol, and nucleoid.
In artificial culture, can be grown often in less than 1 day.

3. Gram-Positive & Gram -Negative bacteria

4. Sterilization, Disinfection, and Infection Control
From the time of debates about the germ theory of disease, killing microbes before they reach patients has been a major strategy for preventing infection.
In fact, Ignaz Semmelweis successfully applied disinfection principles.
The most important methods are:
Sterilization
Disinfection
Asepsis

5. Sterilization
It is complete killing, or removal, of all living organisms from a particular location or material. It can be accomplished by incineration, nondestructive heat treatment, certain gases, exposure to ionizing radiation & some liquid chemicals.

6. Sterilization Types of sterilization:
Physical sterilization: (moist Heat, dry heat, flaming and Incineration)
Chemical sterilization
Ultraviolet Light and Ionizing Radiation

7. A. Physical sterilization
Flaming: The simplest method of sterilization is to expose the surface to be sterilized to a naked flame, as is done with the wire loop used in microbiology laboratories. It can be used equally effectively for emergency sterilization of a knife blade or a needle.
Incineration: disposable material is rapidly and effectively decontaminated in incinerator. It is used to sterilize medical and other bio-hazardous waste before it is discarded with non-hazardous waste.

8. A. Physical sterilization
Dry heat:
It was the first method of sterilization.
Carbonization of organic material and destruction of microorganisms, including spores, occur after exposure to dry heat of 160°C for 2 hours in a sterilizing oven.
This method is applicable to metals, glassware, and some heat-resistant oils and waxes that are immiscible in water and, therefore, cannot be sterilized in the autoclave.
A major use of the dry heat sterilizing oven is in preparation of laboratory glassware.

9. A. Physical sterilization
Moist heat
Autoclave is a sophisticated pressure cooker.
Autoclaves are usually operated at 121°C, which is achieved with a pressure of 15 pounds per square inch for minutes.
The velocity of killing increases logarithmically with arithmetic increases in temperature. For example, the spores of Clostridium botulinum, the cause of botulism, may survive 5 hours of boiling, but can be killed in 4 minutes at 121°C in the autoclave.

10. B. Chemical sterilization
Ethylene oxide is an effective sterilizing agent for heat-labile devices such as artificial heart valves that cannot be treated at the temperature of the autoclave.
formaldehyde vapor and glutaraldehyde solutions can be used without pressure to decontaminate larger areas such as rooms.
oxidizing agents (hydrogen peroxide, ozone).

11. C. Ultraviolet Light and Ionizing Radiation
Ultraviolet (UV) light in the wavelength range of 240 to 280 nm is absorbed by nucleic acids and causes genetic damage, including the formation of the thymine dimers .
Ionizing radiation carries far greater energy than UV light. It, too, causes direct damage to DNA and produces toxic free radicals and hydrogen peroxide from water within the microbial cells.
Cathode rays and gamma rays from cobalt-60 are widely used in industrial processes, including the sterilization of many disposable surgical supplies such as gloves, plastic syringes, specimen containers, some foodstuffs

12. Disinfection
It is the destruction of pathogenic microorganisms by processes that fail to meet the criteria for sterilization.
Disadvantages: Bacterial spores, organisms with waxy coats (eg, mycobacteria), and some viruses may show considerable resistance to the common disinfectants.

13. Types of disinfection A. Physical Methods Filtration Pasteurization
Microwaves
B. Chemical Methods
Alcohol
Halogens
Hydrogen Peroxide
Surface-Active Compounds
Phenolics compounds
Aldehydes

14. A. Physical Methods Filtration:
Both live and dead microorganisms can be removed from liquids by positive- or negative-pressure filtration.
Membrane filters, usually composed of cellulose esters (eg, cellulose acetate.
Membrane filters remove bacteria by mechanical and electrostatic mechanisms by a pore size of 0.2 μm.
Filtration is used for disinfection of large volumes of fluid, especially fluid containing heat-labile components such as serum.

15. Pasteurization
It is the use of heat at a temperature sufficient to inactivate important pathogenic organisms in liquids such as water or milk, but at a temperature lower than that needed to ensure sterilization.
For example, heat-sensitive materials such as milk are exposed to temperatures below boiling (pasteurization) that kills the pathogens in milk but does not sterilize it, at a temperature of 74°C for 3 to 5 seconds.

16. A. Physical Methods
Microwaves:
The use of microwaves in the form of microwave ovens or specially designed units is another method of disinfection.
Microwaves kill by generating heat and these systems are not under pressure.

17. B. Chemical Methods
Chemical disinfectants are classified on the basis of their ability to disinfect:
High-level disinfectants kill all agents, except the most resistant of bacterial spores.
Intermediate-level disinfectants kill all agents, but not spores.
Low-level disinfectants are active against most vegetative bacteria and lipid-enveloped viruses

18. B. Chemical Methods Alcohol:
The alcohols are protein denaturants that rapidly kill vegetative bacteria when applied as aqueous solutions in the range of 70% to 95% alcohol.
They are inactive against bacterial spores and many viruses.
Ethanol (70-90%) and isopropyl alcohol (90-95%) are widely used as skin decontaminants before simple invasive procedures such as venipuncture.

19. B. Chemical Methods Halogens: Iodine Chlorine Hydrogen Peroxide
Surface-Active Compounds:
Surfactants are compounds with hydrophobic and hydrophilic groups that attach to and solubilize various compounds or alter their properties.
Anionic detergents such as soaps

20. B. Chemical Methods
Phenolics: is a potent protein denaturant and bactericidal agents (5% phenol, hexachlorophene and chlorhexidine).
They are the active ingredient in many mouthwash and sore throat preparations.
Glutaraldehyde and formaldehyde are alkylating agents highly lethal to essentially all microorganisms

21. Asepsis
describes processes designed to prevent microorganisms from reaching a protected environment. It is applied in many procedures used in the operating room, in the preparation of therapeutic agents, and in technical manipulations in the microbiology laboratory.
Asepsis applies sterilization and disinfection to create a protective environment.

22. Disinfectants: applied to the surface of non-living objects to destroy microorganisms that are living on the object
Antiseptics: are disinfectant agents that can be used on body surfaces such as the skin to reduce the numbers of normal flora and pathogenic contaminants. They have lower toxicity than disinfectants used environmentally, but are usually less active in killing vegetative organisms.
Sanitization: is a less precise term with a meaning somewhere between disinfection and cleanliness. It is used primarily in housekeeping and food preparation contexts.