Conventional and new technologies are available for the enumeration of Staphylococcus aureus. Here are some commonly used methods: Conventional Methods: 1. Agar Plate Counting: This is a traditional method where a sample is serially diluted and plated on agar plates, typically Mannitol Salt Agar (MSA), which selectively allows the growth of Staphylococcus aureus. After incubation, colonies are counted, and the viable cell count is determined. 2. Most Probable Number (MPN) Method: The MPN method is a statistical technique used for estimating the number of bacteria in a sample. It involves inoculating multiple tubes with different dilutions of the sample and assessing growth based on turbidity. The MPN is determined by comparing the results with a statistical table. New Technologies: 1. Polymerase Chain Reaction (PCR): PCR is a molecular technique used to amplify specific DNA sequences. In the case of Staphylococcus aureus enumeration, quantitative PCR (qPCR) can be used to target specific genes unique to Staphylococcus aureus. The number of bacterial DNA copies is then quantified, providing an estimation of the bacterial load. 2. Real-time PCR (RT-PCR): RT-PCR combines the amplification of PCR with real-time monitoring of the amplification process. It allows for the quantification of DNA or RNA in real-time, providing rapid and accurate results. RT-PCR can be used to detect and quantify Staphylococcus aureus in a sample. 3. Flow Cytometry: Flow cytometry is a technique that analyzes individual cells or particles as they pass through a laser beam. It can be used for the enumeration of Staphylococcus aureus by labeling the bacteria with fluorescent dyes or antibodies specific to the organism. The instrument then detects and counts the labeled bacteria, providing quantitative information. 4. Digital PCR (dPCR): dPCR is a method that partitions the sample into thousands of individual reactions and performs PCR amplification in each partition. The presence or absence of the target DNA is detected in each reaction, and the number of positive partitions is used to estimate the absolute quantity of the target DNA, giving an enumeration of Staphylococcus aureus cells. These new technologies offer advantages such as increased sensitivity, faster results, and the potential for automation. However, it's important to note that the choice of method depends on factors such as the purpose of enumeration, available resources, and the level of accuracy and precision required.

1. Coagulase Test
Author: Multiple Authors
Citation: Multiple Authors. 2010. Coagulase test.
Publication Date: November 2010

2. Positive Tube Coagulase Test Result for Staphylococus aureusA positive tube coagulase test result for Staphylococus aureus after a 24-hour incubation
in coagulase plasma. A positive result is indicated by clotting in the tilted tube. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

3. Negative Tube Coagulase Test Result given by Staphylococcus epidermidis
A negative tube coagulase test result given by Staphylococcus epidermidis after a 24-hour incubation in coagulase plasma. A negative reaction is
indicated by a lack of clotting in the tilted tube. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

4. Coagulase-negative Staphylococci
Coagulase-negative staphylococci. Note the individual cells and lack of large clumps of cells. Cells on the slide coagulase test slide were dried, heat
fixed, and stained with methylene blue.
Photograph is at 1,000X magnification. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

5. Coagulase-positive Staphylococci
Coagulase-positive staphylococci. While some individual cells are observed, the majority of cells are gathered into a large clump, large enough to be
visible to the naked eye. Cells on the slide coagulase test slide were dried, heat fixed, and stained with methylene blue. Photograph is at 1,000X
magnification. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

6. Slide Coagulase Test Results
Slide coagulase test results. (Right) A positive slide coagulase test result for Staphylococcus aureus when mixed with coagulase plasma. A positive
reaction is indicated by visible clumping of Staphylococcus aureus. (Left) A negative slide coagulase test result for Staphylococcus epidermidis when
mixed with coagulase plasma. A negative reaction is indicated by no visible clumping. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

7. Tube Coagulase Test Results
Tube coagulase test results. (Left) A negative tube coagulase test result for Staphylococcus epidermidis after a 24-hour incubation in coagulase
plasma. A negative reaction is indicated by a lack clotting in the tilted tube. (Right) An uninoculated control is also shown. (D. Sue Katz, Rogers State
University, Claremore, OK)
American Society For Microbiology ©

8. Tube Coagulase Test Results
Tube coagulase test results. (Left) A negative tube coagulase test result for Staphylococcus epidermidis after a 24-hour incubation in coagulase
plasma. A negative reaction is indicated by a lack clotting in the tilted tube. (Right) An uninoculated control is also shown. (D. Sue Katz, Rogers State
University, Claremore, OK)
American Society For Microbiology ©

9. Tube Coagulase Test Results
Tube coagulase test results. (Right) A positive tube coagualse test result for Staphylococus aureus after a 24-hour incubation in coagulase plasma. A
positive reaction is indicated by clotting in the tube. (Left) A negative tube coagulase test result for Staphylococcus epidermidis after a 24-hour
incubation in coagulase plasma. A negative reaction is indicated by a lack of clotting in the tube. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

10. Stained Slide Coagulase Test
Staphylococcus aureus cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note the presence of
large clumps of cells. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

11. Stained Slide Coagulase Test
Staphylococcus aureus cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note the presence of
large clumps of cells. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

12. Stained Slide Coagulase Test
Staphylococcus aureus cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained.
Note the presence of large clumps of cells. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

13. Stained Slide Coagulase Test
Staphylococcus aureus cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note the presence of
large clumps of cells. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

14. Stained Slide Coagulase Test
Staphylococcus epidermidis cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note that the cells
are well dispersed and in large clumps. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

15. Stained Slide Coagulase Test
Staphylococcus epidermidis cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note that the cells
are well dispersed and in large clumps. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

16. Stained Slide Coagulase Test
Staphylococcus epidermidis cells observed under an oil immersion lens after the coagulase test slide was dried, fixed, and stained. Note that the cells
are well dispersed and in large clumps. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

17. Coagulase Plasma and Staphylococcus aureus
Close-up of a positive slide coagulase test result given by Staphylococcus aureus mixed with coagulase plasma. A positive reaction is indicated by
visible clumping of Staphylococcus aureus. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

18. Coagulase Plasma and Staphylococcus epidermidis
Close-up of a negative slide coagulase test result given by Staphylococcus epidermidis mixed with coagulase plasma. A negative reaction is indicated
by no visible clumping. (D. Sue Katz, Rogers State University, Claremore, OK)
American Society For Microbiology ©

19. Tube Coagulase Test Results
Tube coagulase test results. (top) A positive tube coagulase test of +3 designation is indicated by a well-formed clot in the test tube. (bottom) A
negative tube coagulase test is indicated by a lack of clotting in the tube. (Diane Hartman, Baylor University, Waco, TX)
American Society For Microbiology ©

20. Postive Tube Coagulase of +2 Designation
A postive tube coagulase test of +2 designation is indicated by a soft clot "stingray" form in the test tube when tilted. (Diane Hartman, Baylor University, Waco, TX)

21. Negative Tube Coagulase Test
A negative tube coagulase test after a 24-hour incubation in coagulase plasma. A negative reaction is indicated by a lack clotting in the tilted tube. (Diane Hartman, Baylor University,
Waco, TX)

22. Tube Coagulase Test Results
Tube coagulase test results.
(bottom)
A positive tube coagulase test result given by Staphylococus aureus after a 24-hour incubation in coagulase plasma. A positive reaction is indicated by clotting in the tilted tube.
(top)