In life, we process a lot of information. From good news, bad news, and everything in between. Do you know what we have to process in the laboratory? Specimens!! From blood cultures, bacteria, body fluids, swabs, and more, the lab handles a lot of specimens. That is why it’s imperative to understand the basics of specimens and processing. Today’s topic in microbiology we will talk about specimen collection and agar plates (media).
Specimen Processing
There is a lot of information concerning specimen processing. For example, swabs are generally not acceptable in the laboratory except for certain samples. In order to remember what samples are acceptable for swabs, remember “swabs are
Specimen Preservation
Preservation is also an important factor in the microbiology department because samples need to be properly stored. For example, remember that “you get bored in the room if you get stuck there for 24 hours.” For urine, boric acid is used to preserve colony counts at room temperature for up to 24 hours. Additionally, another phrase you can use to remember preservation of stool is “Cary and Blair liked to go to school.”
Specimen Storage
In terms of specimen storage, specimens are located in different places depending on what they are. For example, if specimens can’t be processed as soon as possible, they should be stored in the refrigerator. Remember the following phrase, “U store very special food for your cat in the
Priority of Specimens
Every day, we prioritize. Whether it’s watching Netflix, or doing homework lol. Samples in the laboratory also have priority. For example, level 1 (STAT) specimens are those who are critical and invasive like CSF, brain, blood, heart valves, and amniotic fluids. Level 2 specimens are those that are unpreserved such as sputum, tissue, stool, body fluids, drainage, pus, and bone. Level 3 specimens are those that require quantitation such as urine, quantitative tissue, and cath tip. Lastly, level 4 specimens are those that are preserved such as swabs in holding media.
Specimen Requirements and Rejection Criteria
Once you receive a sample in the lab, there are certain requirements that need to be done before you accept it. For example, you need to make sure you have proper labelings, such as patient name, hospital number, date of collection and source. Additionally, there are criteria that need to be followed and criteria that require you to reject a sample. For example, some rejected samples include improper transport temperature, insufficient quantity (QNS), and unpreserved/
Media for Specimens
Once the sample is permitted, you need to know what media you plate your sample on. There are different media that either support or inhibit the growth of some organisms. For example, nutritive/non-selective media support the growth of a wide range of microorganisms. Examples of non-selective media include tryptic soy agar (TSA) with 5% sheep blood and blood agar plate (BAP). Another agar is enriched/enhanced. This type of media supports the growth of fastidious organisms and include chocolate agars. For this, remember, “rich people eat chocolate really fast.” Differentia media are nutritive media that can be differentiated on the basis of certain growth characteristics. For example, MacConkey agars inhibit gram-positive organisms and produce pink colonies for lactose fermenters.
Closing remarks
Microbiology is one of my favorite disciples in the laboratory world and there are so many organisms! However, before we study and dive into the different organisms, we have to go through the basics. Specimen and processing are vital and imperative because the results of the laboratory are limited by the quality of the specimen recieved. I hope you learned something today or just reinforced the knowledge you already know! Continue to learn more, explore the world and process everthing one day at a time and then one thing at a time. You got this!