Bacteriological Culture Media

Culture media provide optimal conditions

for growth & multiplication of bacteria.

BACTERIOLOGICAL LOOP

INOCULATION ON CULTURE PLATES

According to the physical state media may be:

Fluid Media Solid Media

Growth is visualized as

Turbidity Colonies(macroscopic products of 20-30 cell divisions of a single bacterium on a solid medium)

Plating-out technique

Procedure:

SpecimenSpecimen

Loopful of the specimen Loopful of the specimen

Solid media are preferable:

Isolation in pure culture. Identification (colony morphology, effect on medium).

Types of culture media:

1) Simple media

2) Enriched media

3) Selective media

4) Enrichment media

5) Indicator media

6) Selective and indicator media

1- SIMPLE MEDIA

1- SIMPLE MEDIA a- Nutrient broth

Meat Extract

SEA WEEDS

Sea weeds

AGAR POWDER

1- SIMPLE MEDIA b- Nutrient agar

Nutrient Broth + 2% agar-agar

1-SIMPLE MEDIAStaphylococcus aureus on nutrient agar (golden yellow endopigment)

1- SIMPLE MEDIAPs. aeruginosa on nutrient agar (greenish exopigment)

1-SIMPLE MEDIA Proteus on nutrient agar (swarming growth)

2-ENRICHED MEDIA a- Blood agar ( also Indicator Medium)

Nutrient agar +5-10% Blood

2- ENRICHED MEDIA Beta hemolysis on blood agar

2- ENRICHED MEDIA Alpha hemolysis on blood agar

2- ENRICHED MEDIA Non hemolytic organism on blood agar

2- ENRICHED MEDIA Blood agar

2- ENRICHED MEDIA b-Chocolate agar

Heated Blood agar

Haemoglobin

Heat

Haematin

3-SELECTIVE MEDIA Lowenstein Jensen medium for M. tuberculosis

Beaten Eggs + Mineral salts + Malachite Green

4- ENRICHMENT MEDIA Selenite F Broth

5- Differential (indicator) media

Triple Sugar Iron (TSI) agar

TSI agar

6- SELECTIVE INDICATOR (DIFFERENTIAL) MEDIA MacConkey’s medium

Bile Salts+

Lactose+

Neutral Red

6- SELECTIVE INDICATOR (DIFFERENTIAL) MEDIA MacConkey’s medium

Blood Culture

For isolation of bacteria from blood samples in cases of bacteraemia.

Blood culture technique

(1)

(2)

(3)5 – 10 ml blood

Added to 50 – 100 ml fluid medium (broth)

Subculture on Solid medium

(4) Bacterial Growth

Why use Large volume of broth???

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1- Reduction of conc. of antibacterial constituents in blood

2- Multiplication of bacteria

3- Neutralization of antibiotics

Anaerobic Cultivation

-For obligate anaerobes

Achieved by: - exclusion of oxygen

- addition of reducing substance

ANAEROBIC MEDIAa- Robertson’s cooked meat medium

ANAEROBIC MEDIA b- Thioglycollate Broth

GAS PAK SYSTEM FOR ANAEROBIC CULTIVATION

GAS PAK SYSTEM FOR ANAEROBIC CULTIVATION

MCQs

1) MacConkey’s medium:

a) Is an enriched medium.

b) Is an enrichment medium.

c) Contains phenol red as a pH indicator.

d) Gives pink colonies by lactose fermenting

bacteria.

e) Gives green colonies by lactose non-fermenting

bacteria.

2) Blood culture technique is used to diagnose:

a) Sore throat

b) Conjunctivitis

c) Skin infection

d) Sinusitis

e) Bacteraemia

3) All are correct about enrichment media except:

a)They are solid media.

b) Blood agar is not considered an enrichment medium.

c)They have selective properties.

d)They help multiplication of certain species and suppress others.

e)They include selenite broth.

4) All are correct about chocolate agar EXCEPT:

a) It is an enrichment medium.

b) It contains heated blood.

c) It is used to grow fastidious organisms.

d) It is an enriched medium.

e) It is brown in colour.

5) One of the following is used to grow strict anaerobes:

a) Selenite broth

b) MacConkey’s medium

c) Blood agar

d) Lowenstein-Jensen medium

e) Robertson’s cooked meat medium

6) When strict anaerobes are grown in the Gaspak system:

a)They must be inoculated on cooked meat medium.

b)They can be grown on blood agar plates.

c) 50% carbon dioxide must be added.

d) The hydrogen released acts as a catalyst.

e)The palladium in the system acts as a nutrient.

Thank You For Your Attention