Mueller Hinton Agar (MHA)

Mueller Hinton Media contains Beef Extract, Acid Hydrolysate of Casein, Starch and Agar. Beef Extract and Acid Hydrolysate of Casein provide nitrogen, vitamins, carbon, amino acids, sulphur and other essential nutrients. Starch is added to absorb any toxic metabolites produced. Starch hydrolysis yields dextrose, which serves as a source of energy. Agar is the solidifying agent. Final pH 7.3 ± 0.1 at 25ºC

Composition of Mueller Hinton Agar (MHA)

Ingredients	Gms/Litre
Beef extract	2.0
Acid hydrolysate of casein	17.5
Starch	1.5
Agar	17.0

 Uses of MHA

1. The major use of Mueller Hinton Agar is for antimicrobial susceptibility testing. It has become the standard medium for the  Kirby-Bauer method

2. It can be used to cultivate Neisseria

3. It is specified in FDA Bacteriological Analytical Manual for food testing, and procedures commonly performed on aerobic and facultative anaerobic bacteria.

Why MHA is used for antibiotic susceptibility testing?

1. It is a non-selective, non-differential medium. This means that almost all organisms plated on here will grow.

2. It contains starch. Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. It also mediates the rate of diffusion of the antibiotics through the agar.

3. It is a loose agar. This allows for better diffusion of the antibiotics than most other plates. A better diffusion leads to a truer zone of inhibition.

4. MHA shows acceptable batch-to-batch reproducibility for susceptibility testing.

5. MHA is low in sulfonamide, trimethoprim, and tetracycline inhibitors (i.e. concentration of inhibitors thymidine and thymine is low in MHA).

6. It supports the growth of most non-fastidious bacterial pathogens.

Limitations of MHA

1. Numerous factors can affect results: inoculum size, rate of growth, medium formulation and pH. Strict adherence to protocol is required to ensure reliable results.

2. Drug inactivation may result from the prolonged incubation times required by slow growers.

3. This medium is recommended for susceptibility testing of pure cultures only. Inoculum density may affect the zone size.

4. Heavy inoculum may result in smaller zones or too less inoculum may result in bigger zones. 

5. Fastidious organisms may not grow on this medium and may require supplementation of blood. 

6. As antimicrobial susceptibility is carried with antibiotic disc, proper storage of the disc is desired which may affect the potency of the disc. 

Bombay blood group

 The rare, Bombay blood group was first discovered in Mumbai ( Bombay) in 1952 by Dr Y M Bhende. Each red blood cell has antigen over its surface, which helps determine which group it belongs to. In addition to the common A, B, D antigens in the positive blood group people, H antigen is also seen in all blood groups. Thus, in the AB positive blood group,  antigens A, B, D and H are found. A positive will have A, D and H antigens; B positive will have B, D and H antigens. O positive lack A, B but have D antigen. In the Bombay blood group, also called hh, is deficient in expressing antigen H, meaning the RBC has no antigen H. Thus, in hh, there are no A or B antigens, so they are similar to O group. But they alos lack H antigen, hence called Bombay blood group. Could be D positive or negative.

Blood type A is the most ancient, and it existed before the human species evolved from its hominid ancestors

Rarest blood type?

• AB-negative (. 6 percent)
• B-negative (1.5 percent)
• AB-positive (3.4 percent)

O+ is the most frequently occurring blood type and is found in 37 percent of the population. O- is found in six percent of the population

O positive donors who are CMV negative are known as Heroes for Babies at the Red Cross because it is the safest blood for transfusions for immune deficient newborns

Of the eight main blood types, people with type O have the lowest risk for heart disease. People with types AB and B are at the greatest risk

• People with A and AB blood have the highest rates of stomach cancer.

Type O individuals may be more likely to develop peptic ulcers caused by Helicobacter pylori bacterium than other blood types, and that type O women may have more risk of fertility problems

The golden blood type or Rh null blood group contains no Rh antigens (proteins) on the red blood cell (RBC). This is the rarest blood group in the world, with less than 50 individuals having this blood group

Rh incompatibility - If a woman who is Rh negative and a man who is Rh positive have a baby, the fetus may have Rh-positive blood, inherited from the father. Rh incompatibility usually isn't a problem if it's the mother's first pregnancy because the baby's blood does not normally enter the mother's circulatory system. During the birth, the mother's and baby's blood can mix. The mother's body recognizes the Rh protein as a foreign substance and begin making antibodies  against the Rh protein.Rh antibodies are harmless until the mother's second or later pregnancies. If she is next carrying another Rh-positive child, her Rh antibodies will recognize the Rh proteins on the surface of the baby's blood cells as foreign. Her antibodies will pass into the baby's bloodstream and attack those cells. This can make the baby's red blood cells swell and rupture. This is known as hemolytic or Rh disease of the newborn.