What is the optochin test used for?
This test determines whether the bacterium is either sensitive (susceptible) to optochin or resistant to the chemical. The optochin test is widely used in the form of filter paper discs, impregnated with ethylhydrocupreine hydrochloride, which are applied directly to inoculated plates before incubation.
What is an optochin disk?
Optochin Discs are paper discs ready impregnated with Optochin (ethylhydrocuprein hydrochloride) which provide a convenient and reliable alternative to the bile-solubility test.
Which organism is identified by a positive optochin test?
II. Optochin sensitivity allows for the presumptive identification of alpha-hemolytic streptococci as S. pneumoniae, although some pneumococcal strains are optochin-resistant.
What are the bacitracin and optochin test good at differentiating?
The bacitracin test can also be used to differentiate the bacitracin-resistant Staphylococcus from the bacitracin-susceptible Micrococcus. Optochin is also known as ethylhydrocupreine; it is a chemical that inihibits pneumococci but does not affect other α-hemolytic streptococci.
What groups of bacteria are differentiated using optochin?
Optochin, also called ethylhydrocupreine hydrochloride, is used to differentiate S. pneumoniae from S. viridans group, which is also an alpha-hemolytic streptococcus.
What are the reagents used in optochin test?
The optochin test is widely used in the form of filter paper discs. In 1955 Bowen and Jeffries impregnated disks with the reagent ethylhydrocupreine hydrochloride, which are applied directly to inoculated plates before incubation to demonstrate the susceptibility of pneumococcus for identification purpose.
Which bacteria is optochin sensitive?
Streptococcus pneumoniae. S. pneumoniae is a gram-positive, α-hemolytic, catalase-negative, and optochin-sensitive bacterium.
How do you do the optochin test?
For the optochin susceptibility test, the Optochin impregnated disk is placed on a lawn of the organism on a sheep blood agar plate, allowing the antibiotic to diffuse into the medium. The antibiotic inhibits the growth of a susceptible organism, creating a clearing, or zone of inhibition, around the disk.
What is Taxos A?
Taxos A (bacitracin sensitivity) This is a differential test used to distinguish between organisms sensitive to the antibiotic bacitracin and those not. Bacitracin is a peptide antibiotic produced by Bacillus subtilis. It inhibits cell wall synthesis and disrupts the cell membrane.
What does a positive CAMP test look like?
Principle of CAMP test The group B streptococci are streaked perpendicular to a streak of S. aureus on sheep blood agar. A positive reaction appears as an arrowhead zone of hemolysis adjacent to the place where the two streak lines come into proximity.
How do you take optochin test?