Principle of Optochin Sensitivity Test Optochin is water-soluble and diffuses readily into agar medium. Filter paper disks impregnated with optochin can be used in a disk diffusion test format to determine the susceptibility of suspected pneumococci and, thereby, confirm their identity as such.Thereof, is Optochin an antibiotic?
A blood agar plate is streaked for confluent growth with the organism to be tested, and paper disks that have been infused with either bacitracin or optochin are applied to the surface of the agar. Bacitracin is a true antibiotic in that it is an antimicrobial compound which is naturally produced by a microorganism.
Subsequently, question is, what is the mechanism of action for Optochin? Optochin (or ethylhydrocupreine hydrochloride) is a derivative of hydroquinine introduced in 1911 by Morgenroth and Levy with the intention to treat pneumococci infection. In very high dilutions inhibits the growth of representatives of all four groups of pneumococci in vitro.
Hereof, what organism does the Optochin sensitivity test identify?
S. pneumoniae strains are sensitive to the chemical optochin (ethylhydrocupreine hydrochloride). Optochin sensitivity allows for the presumptive identification of alpha-hemolytic streptococci as S. pneumoniae, although some pneumococcal strains are optochin-resistant.
Is Streptococcus oxidase positive or negative?
Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes (capable of growth both aerobically and anaerobically).
What bacteria is resistant to bacitracin?
The activity of bacitracin is primarily against gram-positive organisms: staphylococci, streptococci, corynebacteria, and clostridia. The development of resistance to bacitracin is rare, although it has been reported in S. aureus.What is Optochin disc?
Ethylhydrocupreine hydrochloride (optochin), is a quinine derivative. Optochin selectively inhibits the growth of Streptococcus pneumoniae at very low concentration (5 mg/mL or less). pneumoniae cells surrounding the disk are lysed owing to changes in the surface tension, and a zone of inhibition is produced.How do you do a bacitracin test?
With sterile forceps, obtain a bacitracin disk and place inon the inoculated agar at the intersection of the primary and secondary streaks. Tap the disk with forceps to ensure adherence to the agar surface. Incubate the blood agar plate in ambient air at 35°C for 18 to 24 hours.What is sensitive to bacitracin?
Bacitracin can be used to distinguish Streptococcus pyogenes from other "strep" bacteria, with S. pyogenes being sensitive to bacitracin and others resistant. In this case bacitracin is used to distinguish S. pyogenes from other β-hemolytic streptococci.What does beta hemolytic mean?
Beta hemolysis (β-hemolysis), sometimes called complete hemolysis, is a complete lysis of red cells in the media around and under the colonies: the area appears lightened (yellow) and transparent. Streptolysin, an exotoxin, is the enzyme produced by the bacteria which causes the complete lysis of red blood cells.Why should these tests be run with positive and negative controls?
Answer and Explanation: It is necessary to have positive and negative controls in an experiment to ensure that the results are due to the independent variable.What is novobiocin test?
Novobiocin test is used to differentiate coagulase-negative staphylococci (CONS) and presumptively identify the isolate as Staphylococcus saprophyticus (novobiocin resistant). It is usually performed on urine isolates (isolated from women of reproductive age groups) that are coagulase negative.What does bile soluble mean?
The bile solubility test is a qualitative procedure for determining the ability of bacterial cells to lyse in the presence of bile salts under specific conditions of time and temperature. The test is primarily used to differentiate bile soluble Streptococcus pneumoniae from bile insoluble alpha-hemolytic streptococci.What is chocolate agar made of?
Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C.Does Streptococcus grow on MacConkey Agar?
Streptococcus pneumoniae (S. Hence, it does not grow on MacConkey agar (MA) due to the absence of blood as well as due to the presence of high concentration of bile in the medium which is inhibitory to the growth of S.How is Streptococcus pneumoniae diagnosed?
Diagnosis. The rapid diagnostic test for Streptococcus pneumoniae is also used to confirm the causative bacterium in cases of pneumonia using coughed-up sputum, a nasal cavity swab, or urine as samples.Does the Zone of Inhibition edge indicate?
A larger zone of inhibition around an antibiotic-containing disk indicates that the bacteria are more sensitive to the antibiotic in the disk. If the observed zone of inhibition is greater than or equal to the size of the standard zone, the microorganism is considered to be sensitive to the antibiotic.Where is Streptococcus pneumoniae found?
Streptococcus pneumoniae are most commonly found in the human upper respiratory tract, specifically in the nasopharynx (the nasal passages). Most people carry these bacteria in their nasopharynx, and the harboring of S. pneumoniae within a human is called carriage.What is the shape of Streptococcus pneumoniae?
Streptococcus pneumoniae cells are Gram-positive, lancet-shaped cocci (elongated cocci with a slightly pointed outer curvature). Usually, they are seen as pairs of cocci (diplococci), but they may also occur singly and in short chains. When cultured on blood agar, they are alpha hemolytic.How does Streptococcus pneumoniae attack?
Pneumococcal disease is caused by common bacteria (Streptococcus pneumoniae) that can attack different parts of the body. When these bacteria invade the lungs, they can cause pneumonia; when they invade the bloodstream, they can cause sepsis; and when they invade the covering of the brain, they can cause meningitis.Is blood agar selective or differential?
Blood agar is a differential medium that distinguishes bacterial species by their ability to break down red blood cells. The ability to break down the cells will cause a change in the color of the blood agar. Some media are both differential and selective.What does the bile solubility test indicate?
The bile solubility test is a qualitative procedure for determining the ability of bacterial cells to lyse in the presence of bile salts under specific conditions of time and temperature. The test is primarily used to differentiate bile soluble Streptococcus pneumoniae from bile insoluble alpha-hemolytic streptococci. 
