Microbiology

Microbiology



Microbiology

Aseptic technique refers to a procedure that is performed under sterile conditions. This includes medical and laboratory techniques, such as with microbiological cultures. It includes techniques like flame sterilization. The largest example of aseptic techniques is in hospital operating theatres.

Aseptic technique is the name given to the procedures used by microbiologists to prevent microbial contamination of themselves, which may result in infection, contamination of the environment they are working in (e.g. fomites), and contamination of the specimen they are working on, which is especially important when a pure culture is desired. It is used whenever specimens are to be transferred between media, for example, when subculturing. Such a procedure, using a flame sterilization method, might occur as follows:

A person would assemble the closed tube or flask from which—and the closed tube or flask to which—the specimen is to be transferred, an inoculating loop, and a fire source, all on a clean, preferably microbe-free surface with some overhead protection from airborne microbes.

The person would start the fire, and move the end of the inoculating loop, in a slow back-and-forth motion, through the top of the blue part of the flame. The person would not allow the loop to touch anything except the specimen itself, until the entire procedure is finished.

Preparing to execute the specimen transfer, the person would hold both of the tubes or flasks in one hand, typically the opposite of the writing hand. The person would then open the tube or flask containing the specimen source and briefly hold the top of it in the flame, to kill unwanted microbes.

Quickly, so as to minimize the possible time for contamination of the specimen in the source tube or flask, the person would use the inoculating loop with their writing hand to retrieve the specimen, and then sterilize the top of the tube or flask again before immediately closing it.

Keeping in mind that the specimen on the inoculating loop could be contaminated during every moment it is exposed, the person would repeat the previous step identically with the tube or flask in which the specimen is to be deposited; however, the person would be depositing the sample into the tube or flask.

The human flora is the assemblage of microorganisms that reside on the surface and in deep layers of skin, in the saliva and oral mucosa, and in the gastrointestinal tracts. They include bacteria, fungi, and archaea. Some of these organisms are known to perform tasks that are useful for the human host, however the majority have no known beneficial or harmful effect. Those that are expected to be present, and that under normal circumstances do not cause disease, but instead participate in maintaining health, are deemed members of the normal flora,[1] or microbiota. An effort to better describe the microflora of humans has been initiated; see Human microbiome project.

Gram staining (or Gram's method) is an empirical method of differentiating bacterial species into two large groups (Gram-positive and Gram-negative) based on the chemical and physical properties of their cell ...