Search results
Results from the WOW.Com Content Network
The plates are incubated for 12 hours up to several days, depending on the test that is performed. Commonly used types of agar plates include: Red blood cells on an agar plate are used to diagnose infection. On the left is a positive Staphylococcus infection, on the right a positive Streptococcus culture.
The streak plate method is a way to physically separate the microbial population, and is done by spreading the inoculate back and forth with an inoculating loop over the solid agar plate. Upon incubation , colonies will arise and single cells will have been isolated from the biomass .
An inoculation loop (also called a smear loop, inoculation wand or microstreaker) is a simple tool used mainly by microbiologists to pick up and transfer a small sample of microorganisms called inoculum from a microbial culture, e.g. for streaking on a culture plate. [1] [2] This process is called inoculation.
The inoculation needle after incineration is cooled down on an uninoculated region of the agar plate culture. [1] Too much heat will kill off the inoculum during the direct contact of a flamed inoculation needle. [1] The inoculation needle is withdrawn from the agar culture after obtaining a small colony and the agar plate lid is then replaced.
The inoculation loop is then dragged across the surface of the agar back and forth in a zigzag motion until approximately 30% of the plate has been covered. The loop then is re-sterilized and the plate is turned 90 degrees. Starting in the previously streaked section, the loop is dragged through it two to three times continuing the zigzag pattern.
To obtain uniform growth, the agar plate is streaked with the swab in one direction, rotated 120° and streaked again, rotated another 120° and streaked again. Using an antibiotic disk dispenser, disks containing specific antibiotics are then applied to the plate. This must be done within 15 minutes of inoculation.
Chocolate agar (CHOC) or chocolate blood agar (CBA) is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. [ 1 ] [ 2 ] [ 3 ] It is a variant of the blood agar plate , containing red blood cells that have been lysed by slowly heating to 80°C.
The disc diffusion method involves selecting a strain of bacteria, placing it on an agar plate, and observing bacterial growth near antibiotic-impregnated discs. [12] This is also called the Kirby-Bauer method, [13] although modified methods are also used. [14]