Micobacterium Leprae

Difference between Blood Agar and Chocolate Agar

Hi everyone!

I’ll tell you in short about Nutrient agar first

It is a simple basal medium used for growth of common pathogens

It constitutes peptone water, meat extract and agar

Difference between Blood Agar and Chocolate Agar

What is common between Blood agar and Chocolate agar?

Both are enriched media

Used for the growth of Gram positive cocci and fastidious organisms like Neisseria & Haemophilus species

Can be used to indicate hemolysis

What are fastidious organisms?

They require specialized environments due to complex nutritional requirement

What is the difference between Blood agar and Chocolate agar?

The difference lies in how the media are made

How is Blood agar made?

Nutrient agar is sterilized by autoclave, cooled to 50°C and sterile sheep blood (5-10%) is added gradually and poured into plates

How is Chocolate agar made?

Nutrient agar is sterilized by autoclave, cooled to 75-80°C and sterile sheep blood (5-10%) is added gradually and poured into plates

How is the difference in temperature significant?

Certain organisms such as Haemophilus species require V factor for growth (complex nutritional requirement)

Factor V is present in blood but it is present inside the red blood cells (RBC)

These organisms can not utilize V factor which is trapped inside the RBC’s in Blood agar

When Blood agar is heated to 80-90°C for a few minutes (boiled blood agar), the V factor is released from within the erythrocytes and made available to the organism for utilization

Some strains of Neisseriae and Diphtheroids require V factor too

That’s why these media are superior to plain Blood agar for growing organisms requiring V factor

What is V fatcor?

V fatcor is a coenzyme, Nicotinamide Adenine Dinucleotide (NAD) or Nicotinamide Adenine Dinucleotide Phosphate (NADP) which acts as a hydrogen acceptor in the metabolism of cell

So to conclude, Chocolate agar is a type of blood agar in which the blood cells have been lysed by heating for growing fastidious organisms :)

Did you know?

Modified Thayer Martin is a type of chocolate agar which contains antibiotics (Vancomycin, Nystatin & Colistin) to suppress growth of other bacteria and promote growth of  N gonorrhoeae

*phew* That’s all for today!

The image is my first photoshop work on the site, hope you like it =D

Just to remind you guys, Chocolate agar contains no chocolate, they simply named it after the yummy color :P

-IkaN

nasty moodboard

MORE MIXED MNEMONICS

Microbial Genetics

Infectious bacterial diseases and where to find them

Palmoplantar Rash - Secondary Syphilis

classically a generalised polymorphic rash

usually non-itchy, often affecting palms + soles

important to exclude HIV seroconversion

similar appearance to “target lesions” of erythema multiforme

diagnosis —> syphilis serology

A sample of notes from Medical Virology // I keep the margins empty so that I have space to add in relevant additional material from extra reading

PSEUDOmonas aeroginosa.

Pneumonia 

Sepsis (black lesion on skin).

External otitis (swimmers ear)

UTI,Drug use .

Diabetic osteomylitis

Aminoglycoside„,extended spectrum penicillin(pipracilin,ticarcillin)

Think pseudomonas in burn victims

11.19.17

2 more days until break

Music mood: Mili - Miracle Milk