Question

define and explain: ASO(antistreptolysin), DNase B and neisseria meningitidis

Answer 1

Bacteria cause a number of diseases in humans. The food and the environment is the main source of bacteria.

Millions of people are affected by one or the other bacterial disease in the US, annually. Bacteria are of 3 shapes- rod-shaped (bacillus), round-shaped(cocci), helical (spirilla). Not all strains of bacteria are harmful but mostly cocci cause diseases in humans by producing endotoxins and exotoxins.

ASO (antistreptolysin)

Streptococcus bacteria are harmful to humans. Mostly, group A Streptococcus bacteria. Streptococcus pyogenes cause infection by entering through the oral route or through the wound or cut on the skin and production of toxin called streptolysin O. 'O' means that the toxin is oxygen-labile. It is hemolytic in nature.

They cause bacterial endocarditis, glomerulonephritis, rheumatic fever.throat infection,etc.

On infection, the body produces antibodies against the toxin within a week.

The levels of antibodies produced against streptolysin O are tested so as to confirm whether the patients' symptoms are due to streptococcal infection or not.

ASO test is the abbreviation for the Antistreptolysin test. This is a test that helps in the determination of titers of Antistreptolysin against the bacterial toxin streptolysin O in the blood sample of the patient. Generally, a titer below 200 IU/mL in adults and below 100 IU/mL in infants is considered as normal. Above these values, the streptococcal infection is positive.

DNase B

The group A, C & G strains of streptococci that cause beta hemolysis secrete an enzyme, DNase B.

The levels (titers) of DNase B in the blood sample of the patients help to confirm past streptococcal infection.

The titers at which the anti-DNase B test is normal are less than 85 units/milliliter (mL) in adults and less than 60 units/mL in small children.

Thus to confirm the streptococcus infections at 90%, the blood tests are done to check the titers of antibodies like Antistreptolycin and anti-DNase.

Neisseria meningitidis

Neisseria meningitidis a gram-negative diplococcus. It is the causative agent of the disease meningitis & Meningococcal septicemia.

It is specific to humans. It causes fatigue, fever, and headache and can rapidly progress to neck stiffness, coma, and even death (in 10% of cases).

The bacteria are found in the nasopharyngeal area of carriers.it is spread through close contact, unhygienic practices, saliva, and respiratory secretions during coughing, sneezing.

Menactra and Menveo are the 2 vaccines that are given to children in the US in their preteens & teens.

Maintaining hygiene in day to day life is the best practice to reduce bacterial infections.