Eosin methylene blue agar (EMB) is a selective and differential medium used to isolate fecal coliforms. Eosin Y and methylene blue are pH indicator dyes which combine to form a dark purple precipitate at low pH; they also serve to inhibit the growth of most Gram positive organisms.
What does an EMB do?
EMB is a differential microbiological medium, which slightly inhibits the growth of Gram-positive bacteria and provides a color indicator distinguishing between organisms that ferment lactose (e.g., E. coli) and those that do not (e.g., Salmonella, Shigella).
What bacteria grows on EMB?
Some gram-positive bacteria, such as enterococci, staphylococci, and yeast will grow on this medium and usually form pinpoint colonies. Non-pathogenic, non-lactose-fermenting organisms will also grow on this medium.
What makes EMB Agar selective?
EMB contains the dyes eosin and methylene blue that inhibit the growth of gram-positve bacteria. Therefore, EMB is selective for gram-negatives. In addition, the gram-negatives that grow can be differentiated based on their ability to ferment lactose.
What does Levine EMB test for?
Levine EMB Agar is a slightly selective and differential medium for the isolation, cultivation and differentiation of gram-negative enteric microorganisms isolated from both clinical and nonclinical specimens. It is widely used for the examination of materials of sanitary importance for the presence of coliforms.
How do you make an EMB?
Preparation Instructions Suspend 36 grams of EMB Agar in 1000 mls of distilled water. Heat to dissolve the medium completely. Dispense and sterilize by autoclaving at 15 lbs. pressure (121 °C) for 15 minutes.
Why does EMB inhibit gram positive?
Most bacteria that ferment lactose form colonies on EMB agar that are dark blue to black with a metallic sheen due to precipitation of the dyes by the acid by-products of fermentation. The growth of Gram positive bacteria is generally inhibited on EMB agar because of the toxicity of methlyene blue dye.
What are the selective agents found in EMB?
The selective/ inhibitory agents of EMB are the dyes eosin Y and methylene blue. Methylene blue inhibits the gram + bacteria (eosin to a lesser extent), while eosin changes color, to a dark purple, when the medium around the colony becomes acidic.
What is EMB?
An endometrial biopsy (EMB) is an office procedure in which a sample of cells from inside the uterus is collected. An EMB is usually done for women who have irregular or heavy bleeding in order to diagnose uterine abnormalities like uterine cancer, precancerous cells or polyps.
What color is E coli on EMB?
Normally-colored or colorless colonies indicate that the organism ferments neither lactose nor sucrose and is not a fecal coliform. Escherichia coli often produces a metallic green sheen on EMB.
What ingredient makes EMB differential?
lactose The differential ingredient is lactose. Fermentation of this sugar results in an acidic pH and causes the pH indicator, neutral red, to turn a bright pinky-red color. Thus organisms capable of lactose fermentation such as Escherichia coli, form bright pinky-red colonies (plate pictured on the left here).
What types of bacteria grow on 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 is blood agar used?
One of the essential uses of blood agar is to observe the hemolysis caused by the growing bacteria, which can then be used for the identification of the organism. Blood agar is mostly used for the cultivation of pathogenic organisms that are capable of producing extracellular enzymes that cause hemolysis of the blood.
How does EMB inhibit gram positive?
Most bacteria that ferment lactose form colonies on EMB agar that are dark blue to black with a metallic sheen due to precipitation of the dyes by the acid by-products of fermentation. The growth of Gram positive bacteria is generally inhibited on EMB agar because of the toxicity of methlyene blue dye.
Is E coli gram positive?
Escherichia Coli is a Common Intestinal Bacteria. E. coli is a Gram negative anaerobic, rod-shaped, coliform bacteria of the genus Escherichia, commonly found in the lower intestine of humans and animals.
The biopsy is performed by using a small straw-like tube through the cervical opening and into the uterine cavity. Using the tube, the provider will take a small sample of cells from the inner layer of the uterine wall.