how can you tell? The results suggest that both E. coli and S. aureus are gram-positive organisms. examples of selective media. (1, 2, and 3) Blood agar as a selective medium. Columbia CNA Agar with 5% Sheep Blood is a selective and differential medium used for the isolation and differentiation of gram-positive microorganisms from clinical and nonclinical materials . Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. The difference between selective and differential media is mainly due to the following factors: Intended use of the media: The purpose of both selective and differential media differs.A selective media only permits the development of particular organisms, while a differential media discerns one species of the organism from the other growing on the similar substrate. Overnight broth cultures of Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis (on plate). Blood agar as a differential medium. Hektoen Enteric (HE) Agar was introduced in 1968 by Sylvia King and William I. Metzger. MacConkey agar is a selective and differential medium designed to isolate and identify gram-negative bacteria while suppressing the growth of gram-positive bacteria. Phenylethyl alcohol agar is used for the isolation of most gram-positive organisms. Often, in a clinical setting, the most helpful type of medium is one that is both selective and differential. One blood agar plate 3. MacConkeyâs (MAC), Blood agar (BAP) and Mannitol Salt (MSA) are three examples of these specialized types of media. It detects hemolysis by cytolytic toxins that are secreted by some strain of bacteria. Selective media allows the selection of a group of organisms but not others.Examples are: McConkey Agar, Blood Agar, Mannitol Salt Agar, and EMB. ECC ChromoSelect Selective Agar is a selective medium recommended for the simultaneous detection of Escherichia coli and coliforms in water and food samples. Organism Appearance Hemolysis result Staphylococcus epidermidis Non-hemolytic colonies Î³-hemolysis Streptococcus pyogenes Large clear zones beta-hemolysis Streptococcus pneumoniae Green zone around organism alpha-hemolysis Unknown 4 Large clear â¦ Is PEA blood agar a selective or differential medium? BCYE Agar is â¦ Buffered Charcoal Yeast Extract Agar Medium(BCYE Medium) M813I Intended use Recommended for selective isolation and cultivation of Legionella species from cooling towers, water samples, `clinical and other materials. Selective vs. differential media The usefulness of blood agar The term denoting the process of growing bacteria Skills Practiced. Distinguish between a pure culture and a mixed culture. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis. You Have Isolated Gram-positive Cocci From A Throat Culture That You Cannot Identify As Staphylococci Or Streptococci. Blood agar can be made selective for certain pathogens by the addition of antibiotics, chemicals or dyes. 3. Blood Agar/MacConkey Biplate, (Blood/MAC), 15x100mm plate, order by the package of 10, by Hardy Diagnostics: Section I: MacConkey Agar is for the selective and differential isolation of gram negative bacteria, especially the Enterobacteriaceae. Blood agar, EMB agar, and MacConky agar are examples of differential media. The active ingredient, phenylethyl alcohol, inhibits or markedly reduces growth of Gram negative organisms by interfering with DNA synthesis. Blood agar is an enriched, differential media used to isolate organisms and detect hemolytic activity, meaning they rupture the blood cells (lysis). Blood agar is a differential medium that distinguishes bacterial species by their ability to break down red blood cells. Differential and selective media are special types of agar that can can exclude certain types of bacteria and even test for certain bacterial metabolic capabilities. Î²-hemolytic activity will show lysis and complete digestion of red blood cell contents surrounding â¦ Blood Agar Plate 5% sheep blood from random sheep Enriched with selective and differential media Bacteria may release enzymes eating RBCâs 3 types of results may occur (pg 101) Alpha hemolysis: narrow partial clearing around bacteria, sometimes greenish color, partial digestion Beta hemolysis: clear zone, complete digestion Gamma hemolysis: no hemolysis, no change, no digestion. ; Hektoen enteric agar is selective for Gram-negative bacteria. B) Explain what alpha, beta and gamma hemolytic results mean and what they look like on the blood agar plate. Blood agar is a bacterial growth medium which contains 5% sheep's blood. Sterile swabs and sterile toothpicks 5. Blood contains inhibitors for certain bacteria such as Neisseria and Haemophilus genera and the blood agar must be heated to inactivate these inhibitors and to release essential growth factors (e.g., V factor). So, media could be both selective as well as differential. A) Blood agar is selective, differential, or both? Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms. Rabbit plasma 6. It is not selective, and will grow many different types of microbes. The ingredients help even the sublethally injured coliforms to grow rapidly, Tergitol â¢ inhibits Gram-positive as well as some Gram-negative bacteria other than coliforms. Phenylethyl alcohol agar (PEA) is a selective medium used to cultivate Gram positive organisms. These media are non selective and they contain general nutrients which required for the growth of wide range of microorganisms. 2. It is a selective as well as differential medium. While differential media is used in order to differentiate between closely related organisms.Examples are: McConkey, Blood, and EMB Agars. If these bacteria do not present a health hazard, why are these tests being developed? Why is MacConkey agar selective as well as differential? Blood agar is growth medium for bacterial which considered to be differential but not selective & it is an enriched medium that provides a rich nutrient for many types of bacteria. Blood Agar (BAP) is another type of differential medium. 3% Hydrogen peroxide solution Procedure: (work in pairs) 1. When an agar plate is inoculated, why is the loop sterilized after the initial inoculum is put on? BAP is rich in nutrients and contains sheep blood. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C. Sheepâs blood 50 ml Agar 15 g pH 7.2 â 7.6 Figure 01: Blood Agar Plate What is Macconkey Agar? It is a partially selective medium which applies the ability of staphylococci to reduce tellurite to tellurium and to detect lecithinase from egg lecithin. C) MacConkey agar is selective, differential or both, and explain why (what are the specific components of the agar)? Is The Gram Stain Of Significant Importance In Identifying The Organisms Studied In This Exercise? YM (yeast extract, malt extract agar) has a low pH, deterring bacterial growth. Phenylethyl Alcohol Agar. It The ability to break down the cells will cause a change in the color of the blood agar. 1. Blood agar is a differential medium because it helps detect and differentiate haemolytic bacteria such as Streptococcus species. Selective media = Media providing a means of isolating a particular species or type or microorganisms, while inhibiting the growth of others (e.g., EMB, MAC, T-7, MSA, etc.). Nutrient media: These media are also called general purpose media. ; MacConkey agar is for Gram-negative bacteria. Selective: high salt selects for Staphylococci. One mannitol salt agar (MSA) plate 2. They formulated HE Agar medium while working at the Hektoen Institute in Chicago, to increase the recovery Salmonella and Shigella from clinical specimens. Explain. Eosin methylene blue agar is a selective and differential medium used for isolation and differentiation among members of the Enterobacteriaceaeâthe enteric (gut) bacteria. Heating of blood agar converts it into chocolate agar (heated blood turns a chocolate color) and supports the growth of these bacteria.. Briefly Explain. 4. Is Blood Agar Selective Or Differential? Tests to determine the presence of Bacteroides in clams and oysters are being developed. Blood agar is a bacterial growth medium which is nutrient agar supplemented with a5% concentration of sheep blood. Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow. Blood agar medium is, however, differential. 3. 1.0 and 0.1 ml pipets 7. Medical Applications EMB agar, like DOC, allows a quick preliminary indication of whether a specimen contains enteric pathogens. Baird-Parker Agar is widely used and is included in many standard procedures for testing foods, â¦ Exercise 4: Pure bacterial colonies. The key difference between blood agar and MacConkey agar is that blood agar is an enriched differential medium used to isolate fastidious microorganisms and detect their hemolytic activity whereas MacConkey agar is a selective and differential medium used to differentiate between non-fastidious gram-negative bacteria from gram-positive bacteria. Data Sheet 7 â Selective and/or differential media and Serial Dilution Complete the following table with your blood agar plate results. Some media are both differential and selective. 1. Examples includes crystal violet blood agar to select Streptococcus pyogens from throat swabs, and kanamycin or neomycin blood agar to select anaerobes from pus. Media are included with necessary nutrients for â¦ Blood agar is one type of differential medium, allowing bacteria to be distinguished by the type of hemolysis produced. It is the selective and differential medium for coliforms. Define a bacterial colony. PEA also prevents Proteus species from swarming across the surface of the agar. Agar was published in 1962. It will display a color change in the presence of bacteria that can lyse (break down) the red blood cells in the medium. Summary - Selective vs Differential Media Culture media are used to grow, isolate, differentiate and identify microorganisms. MacConkey agar medium has both selective and differential properties. Advanced formula controls the swarming of Proteus. Blood agar is a differential medium that distinguishes bacterial species by their ability to break down red blood cells. Composition of Blood Agar. 2. Examples of selective media include: Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria.