identifying gram positive cocci
IDENTIFYING GRAM POSITIVE COCCI
As mentioned in Exercise 8, “Identifying Gram Negative Rods”, identifying bacteria is a common activity in the microbiology lab. Like the game Clue™, each time you gather a piece of information to solve the mystery, you gather some information that supports some identities and eliminates others from contention. In the lab, the process continues as you gather more information until only one microbe remains and all others have been eliminated as possibilities. Thus, identification of microbes is a process of elimination based on logic and carefully-performed tests to determine the capabilities of the unknown microbe.
The pieces of evidence used in the microbiology lab are your observations of the shape, morphology, Gram reaction, and the results from biochemical tests performed using a pure culture of an unknown organism. Results are compared to tables of known results for all bacteria with similar shape, morphology and Gram reaction to see where similarities and differences occur. Such tables in VirtualUnknown™ Microbiology can be accessed by clicking “Identification Matrix” under the “View” option in the lab. Displayed will be tests along the left and the microbes still possible (based on the results you have input) across the top. Every time you record a test result, the Identification Matrix shrinks as the columns with results that directly conflict with those you record for your unknown are eliminated from the table. Those microbes with results that agree with those you record (or that are displayed as [+], d, or [-]) remain possibilities and more testing is needed.
A way of gauging how much progress is being made is to observe the Virtual Lab Report to see how each test result reported increases the number of microbes eliminated. Ideally, every test conducted would reduce the number of possible microbe IDs in half (just as each round of the “March Madness” basketball tournament reduces the number of possible
As mentioned in Exercise 8, “Identifying Gram Negative Rods”, identifying bacteria is a common activity in the microbiology lab. Like the game Clue™, each time you gather a piece of information to solve the mystery, you gather some information that supports some identities and eliminates others from contention. In the lab, the process continues as you gather more information until only one microbe remains and all others have been eliminated as possibilities. Thus, identification of microbes is a process of elimination based on logic and carefully-performed tests to determine the capabilities of the unknown microbe.
The pieces of evidence used in the microbiology lab are your observations of the shape, morphology, Gram reaction, and the results from biochemical tests performed using a pure culture of an unknown organism. Results are compared to tables of known results for all bacteria with similar shape, morphology and Gram reaction to see where similarities and differences occur. Such tables in VirtualUnknown™ Microbiology can be accessed by clicking “Identification Matrix” under the “View” option in the lab. Displayed will be tests along the left and the microbes still possible (based on the results you have input) across the top. Every time you record a test result, the Identification Matrix shrinks as the columns with results that directly conflict with those you record for your unknown are eliminated from the table. Those microbes with results that agree with those you record (or that are displayed as [+], d, or [-]) remain possibilities and more testing is needed.
A way of gauging how much progress is being made is to observe the Virtual Lab Report to see how each test result reported increases the number of microbes eliminated. Ideally, every test conducted would reduce the number of possible microbe IDs in half (just as each round of the “March Madness” basketball tournament reduces the number of possible