Why Is Sheep Blood Agar Used For Throat Cultures?

Why is sheep blood used in blood agar?

Blood agar contains general nutrients and 5% sheep blood. It is useful for cultivating fastidious organisms and for determining the hemolytic capabilities of an organism. Some bacteria produce exoenzymes that lyse red blood cells and degrade hemoglobin; these are called hemolysins.

What is the clinical reason that throat cultures are performed on blood agar?

Blood agar is commonly used to isolate not only streptococci, but also staphylococci and many other pathogens. Besides providing enrichments for the growth of fastidious pathogens, Blood agar can be used to detect hemolytic properties.

What kind of agar is used during throat swabbing and why?

When strep is suspected, the throat material is cultured on blood agar that has been prepared as a broth and poured into petri dishes (plates) where it solidifies into a gel. Blood agar is usually made from the cell walls of red algae (also trypticase soy, heart infusion, or Todd-Hewitt agar) and sheep’s blood.

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What organism is pathogenic in the throat?

S pyogenes, the most important bacterial pathogen of the throat, is a group A beta-hemolytic Streptococcus (GABHS), and the infection is commonly known as strep throat or streptococcal sore throat.

What bacteria grows on sheep blood agar?

Blood Agar is used to grow a wide range of pathogens particularly those that are more difficult to grow such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria species. It is also required to detect and differentiate haemolytic bacteria, especially Streptococcus species.

Why dont we use human blood agar?

Agar prepared with human blood is not recommended, partly because of the safety risk to laboratory personnel, but mainly because it is said to result in poor bacterial isolation rates, although there are few published data to support this (2).

Why is chocolate agar used in throat culture?

It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis. The agar is named for its color and contains no chocolate products.

What bacteria does a throat culture test for?

A throat culture or strep test is performed by using a throat swab to detect the presence of group A streptococcus bacteria, the most common cause of strep throat. These bacteria also can cause other infections, including scarlet fever, abscesses, and pneumonia.

Why are throat cultures are the gold standard for gas diagnosis?

Throat culture remains the gold standard for diagnosing streptococcal pharyngitis. Failure to isolate β-hemolytic streptococci in a carefully obtained and accurately interpreted throat culture rules out the diagnosis of streptococcal sore throat for practical purposes.

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What if throat culture is negative?

A negative throat culture may mean that the cause of your infection is a virus, rather than bacteria or fungus. Some viruses that cause throat infections include: Enterovirus. Epstein-Barr virus.

What do you do for a throat culture?

Your doctor will press your tongue down with a flat stick (tongue depressor) and then examine your mouth and throat. A clean swab will be rubbed over the back of your throat, around your tonsils, and over any red areas or sores to collect a sample. The sample may also be collected using a throat washout.

How much does a throat culture cost?

In the base case analysis, the cost of obtaining a throat culture was estimated to be $2.40. At a cost of culture greater than $4.46, the EIA Only strategy would be the least expensive, but the Culture strategy would be the most effective. We estimated the cost of reporting culture results to patients to be $0.63.

Why is a throat culture done?

The purpose of a throat swab culture is to detect the presence of organisms in the throat that could cause infection. For example, the presence of group A streptococcus bacteria (Streptococcus pyogenes) in your throat is a key sign that you may have strep throat.

When do you repeat a throat culture?

Repeat throat culture should be considered after completion of this form of therapy to document eradication of group A strep, but should not be obtained routinely after therapy of acute streptococcal pharyngitis.

What kinds of bacteria are commonly found in the throat?

Group A streptococci are bacteria commonly found in the throat and on the skin. People may carry GAS in the throat or on the skin and not become ill.

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