 بسم الله الرحمن الرحيم  وَقُل رَّبِّ أَدْخِلْنِي مُدْخَلَ صِدْقٍ وَأَخْرِجْنِي مُخْرَجَ صِدْقٍ وَاجْعَل لِّي مِن لَّدُنكَ سُلْطَانًا نَّصِيرًا  سورة الاسراء الآيات (80) بسم الله الرحمن الرحيم

CULTURE MEDIA AND STERELIZATION

CULTURE MEDIA Culture media are used for recognition δ identification of microorganism

Common ingredients of culture media 1. PEPTONE 2.Meat extract 3.Nacl a. Melting point 92-95 c b. solidifing point 42-45 c 4. Agar agar c. concentration 1.5-2% (solid) 0.4- 0.8% (semisolid)

e.g. nutrient broth (Fluid)media 1.Liquid TYPES OF CULTURE MEDIA A. PHYSICAL STATE(CONSISTENCY)OF MEDIA e.g. nutrient broth (Fluid)media 1.Liquid 2.solid media e.g. nutrient agar ,blood agar 3. Semisolid Media

Blood agar and nutrient agar Solid culture medium Fluid culture medium (nutrient broth) Blood agar and nutrient agar

B. USE OF MEDIA 1)simple media e.g. nutrient agar and nutrient broth. 2)special-purpose media

Nutrient agar Nutrient broth Simple culture media

ENRICHED MEDIA Simple media enriched with appropriate substance ,e.g. Blood ,glucose ,serum and ascetic fluid ,most commonly used to cultivate fastidious microorganism like streptococci

Chocolate agar Blood agar (Enriched media)

SELECTIVE MEDIA Containing inhibitory substance ( e.g. bile salt ,antibiotic, dyes…etc) which favour the growth of concerned microorganism and inhibit the growth of other . e.g. Macon key's agar

Slective medium for gram negative bacilli (contains bile salts which inhibit the growth of gram positive microorganisms)

DIFFERENTIAL MEDIA Certain species produce characteristic growth that can be easily recognized, or can produce certain effects in the media e.g. hemolytic and non-hemolytic species on blood agar ,MacConkeys agar differintiates between lactose fermenter and non lactose fermenter gram negative bacilli, nutrient agar differintiates between species of genus Staphylococcus

Haemolytic bacteria on blood agar Non haemolytic bacteria on blood agar

MacConkey′s agar(selective and differential medium) selective for gram negative bacilli and differentiate between lactose fermenter and non lactose fermenter gram negative bacilli)

Staphylococcus albus (white colonies) on nutrient agar Staphylococcus citreus (lemon yellow colonies) on nutrient agar

Staphylococcus aureus on nutrient agar (golden yellow colonies)

Other uses of culture media…e.g Antibiotic sensitivity test on Mueller-Hinton agar

E- Test( strip of antibiotic contains gradients of concentrations to determine the minimum inhibitory concentration MIC)

STERELIZATION DISINFECTION Is the destruction or removal of all living organisms in or on an object DISINFECTION Is the destruction of pathogenic microorganism only

TYPES OF STERELIZATION 1. PHYSICAL METHODS 2. CHEMICAL METHOD

A-Heat 1. dry heat A-flaming B-hot air oven C- infra-red radiation PHYSICAL METHOD A-Heat 1. dry heat A-flaming B-hot air oven C- infra-red radiation

Hot air oven (Temperature 160 C ⁰ for one hour) used for sterilization of glasses , powders oils and surgical instrument)

Infrared radiation

2.MOIST HEAT a. At a temperature below 100 c e.g. pasteurization of milk 100 c: b. At a temperature of min. I. Boiling at 100 c for 5-10 II. steaming at 100 c e.g. Tyndallization c. At a temperature above 100 c e.g. auto clave

Autoclave (Temperature 121C⁰ + Pressure 15 IB / inch) used for sterilization of bacteriological media and surgical instruments.

1)Direct sun light 2)Ultra violet light 3)Ionizing radiation B. Radiation 1)Direct sun light 2)Ultra violet light 3)Ionizing radiation

Sterilization of operating theater by ultraviolet light

C. Filtration to render fluids sterile e. g C. Filtration to render fluids sterile e.g. serum ,antibiotic solution ,sugar ,toxins

II.CHEMICAL METHODS A-DISINFECTANTS e.g. acids(toxic to living tissue) B-ANTISEPTICS e.g. chlorine and iodine(safely applied to living (tissue

TESTING THE EFFICIENCY OF STERILIZATION 1.Chemical indicators control tubes brown s sterilization 2.Adhesive tape Bowie ---dick auto clave tape test

Browns′ sterilization control tubes (contain red solution change to green when sterilization is effective)

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