What tests are performed in a microbiology lab?

What tests are performed in a microbiology lab?

List of Laboratory Tests – Microbiology

• Aspirate culture & sensitivity.
• Aspirate for AFB.
• Blood culture & sensitivity.
• Cholera ag.
• Chlamydia.
• CSF- culture & sensitivity.
• Ear culture & sensitivity.
• Endocervical swab.

Why do microbiologists transfer bacteria from 1 plate to a selective or differential media?

Why do microbiologists transfer bacteria from 1 plate to a selective or differential media? They want to make a mixed culture. You are using the microscope to view bacteria.

Is MacConkey agar selective or differential?

MacConkey agar is an example of a medium that is both differential and selective. The presence of bile salts, as well as crystal violet, within the media prevent gram-positive organisms from growing.

Is chocolate agar selective or differential?

Chocolate agar, a differential medium for gram-positive cocci. Journal of Clinical Microbiology.

What bacteria does not grow on blood agar?

Blood agar is an enriched, bacterial growth medium. Fastidious organisms, such as streptococci, do not grow well on ordinary growth media. Blood agar is a type of growth medium (trypticase soy agar enriched with 5% sheep blood) that encourages the growth of bacteria, such as streptococci, that otherwise wouldn’t grow.

What grows MacConkey Agar?

MacConkey agar is selective for Gram-negative organisms and helps to differentiate lactose fermenting gram-negative rods from non-lactose fermenting gram-negative rods. It is primarily used for the detection and isolation of members of family enterobacteriaceae and Pseudomonas spp.

What is the purpose of chocolate agar?

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.

What is MacConkey agar used for?

MacConkey Agar (MAC) is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose. Bile salts and crystal violet inhibit the growth of Gram positive organisms. Lactose provides a source of fermentable carbohydrate, allowing for differentiation.

What does MacConkey agar test for?

MacConkey agar is used for the isolation of gram-negative enteric bacteria. It is used in the differentiation of lactose fermenting from lactose non-fermenting gram-negative bacteria. It is used for the isolation of coliforms and intestinal pathogens in water, dairy products and biological specimens.

How do you make nutrient agar?

How to prepare nutrient agar?

1. Suspend 28g of nutrient agar powder (CM0003B) in 1L of distilled water.
2. Mix and dissolve them completely.
3. Sterilize by autoclaving at 121°C for 15 minutes.
4. Pour the liquid into the petri dish and wait for the medium to solidify.

What is the function of nutrient agar?

Nutrient Agar is used for the cultivation of bacteria and for the enumeration of organisms in water, sewage, feces and other materials. Early in the 20th century, the American Public Health Associa- tion published the formula for a general purpose medium for the growth of a wide variety of nonfastidious microorganisms.

What is the use of blood agar?

Many species of bacteria produce toxic by-products that are capable of destroying red blood cells. Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.

What is the difference between agar medium and broth?

The only difference between broth and agar media is that broths do not contain an agar component. We use broth tubes primarily for specific assays, or (rarely) for bacteria that will not form colonies on a solid surface. Unlike preparation of agar plates, tubes are prepared with media already in the incubation vessel.

Why is agar slant useful?

Agar slants can be used to culture bacterial cells for identification. Attempting to identify bacteria from a large sample is difficult because bacteria are small and can be difficult to find. Agar slants are also useful in maintaining bacterial cultures, more so than stacks of Petri dishes.

How do you make blood agar?

Preparation of Blood Agar

1. Suspend 28 g of nutrient agar powder in 1 litre of distilled water.
2. Heat this mixture while stirring to fully dissolve all components.
3. Autoclave the dissolved mixture at 121 degrees Celsius for 15 minutes.
4. Once the nutrient agar has been autoclaved, allow it to cool but not solidify.

What is the purpose of broth in microbiology?

The purpose of broth in a microbiology laboratory is to provide a growth medium for bacteria by giving a constant and steady amount of nutrients that allows the bacteria to reproduce quickly.

How many types of media are there in microbiology?

These are classified into six types: (1) Basal media, (2) Enriched media, (3) Selective (4) Indicator media, (5) Transport media, and (6) Storage media. 1. BASAL MEDIA. Basal media are those that may be used for growth (culture) of bacteria that do not need enrichment of the media.

What are examples of selective media?

Examples of selective media:

• Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria.
• YM (yeast extract, malt extract agar) has a low pH, deterring bacterial growth.
• MacConkey agar is for Gram-negative bacteria.
• Hektoen enteric agar is selective for Gram-negative bacteria.

What is broth and agar?

Agar is solidified media while broth is liquid media. 2. Agar is used for the Isolation and preservation of bacterial culture while N. broth is used to prepare bacterial Culture for growth and cultivation for production.

What are the different types of agar plates?

Types of Agar Plates

• Blood Agar Plates. Blood agar plates (BAP) are made by adding five to ten percent sheep or horse blood to the nutrient medium.
• Nutrient Agar Plates. Nutrient agar grows the largest variety of microbes, typically fungi and bacteria.
• MacConkey Agar Plates.
• Other Kinds of Agar Plates.

What broth means?

bouillon

What type of media is nutrient agar?

Nutrient agar is a general purpose medium supporting growth of a wide range of non-fastidious organisms. It typically contains (mass/volume): 0.5% Peptone – this provides organic nitrogen. 0.3% beef extract/yeast extract – the water-soluble content of these contribute vitamins, carbohydrates, nitrogen, and salts.

What Bacteria grows on nutrient agar?

What Grows on Nutrient Agar? Microorganisms need food, water and a suitable environment in order to survive and grow. Nutrient agar provides these resources for many types of microbes, from fungi like yeast and mold to common bacteria such as Streptococcus and Staphylococcus.

What is differential agar?

Differential media are bacteriological growth media that contain specific ingredients to allow one to distinguish selected species or categories of bacteria by visual observation. Blood agar is one type of differential medium, allowing bacteria to be distinguished by the type of hemolysis produced.

What is selective agar?

Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms. Tellurite agar, therefore, is used to select for Gram-positive organisms, and nutrient agar supplemented with penicillin can be used to select for Gram- negative organisms.

What makes EMB Agar selective?

Eosin Methylene Blue (or EMB) Agar is a Selective & Differential Medium. The selective and differential aspects are due to the dyes Eosin Y and Methylene Blue, and the sugars lactose and sucrose in the medium. It is Selective because it encourages some bacteria to grow while inhibiting others.

What is primary media microbiology?

Primary media. The first media used to culture a specimen. The basic purpose of primary media. 1) Culture all bacterial species present to determine which species predominates.

Is MacConkey Agar defined?

MacConkey Agar is a selective medium, Is it also a defined or an undefined medium? Why is that formulation desirable? Undefined, it’s beneficial because it gives a wide variety of growth ability. Only gram-negatives will grow on MacConkey, so you always want to streak to something that you know it will grow on.