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Introduction of Citrate Utilization Test Sodium citrate is the only carbon source in citrate agar composition. On the basis of citrate utilization, some bacteria can be differentiated. Klebsiella pneumoniae and Citrobacter freundii are citrate positive while Escherichia coli and Shigella species are negative.  Simmons Citrate Agar is recommended for differentiation of the members of Enterobacteriaceae as well as other Gram-Negative rods ( Pseudomonas, Acinetobacter) on the basis of citrate utilization from clinical and non-clinical samples. Principle of Citrate Test A citrate test...

Introduction of Bacterial Coagulase Test The bacterial coagulase test is an enzymatic test that is used to differentiate Staphylococcus aureus (positive) from coagulase-negative staphylococci (CoNS). Coagulase is an enzyme produced by S. aureus that converts soluble fibrinogen of plasma to insoluble fibrin. S. aureus produces two forms of coagulase i.e. bound and free coagulase. Slide coagulase test is proceeded to detect bound coagulase or clumping factor. A tube coagulase test is performed to detect free coagulase. Principle of Bacterial Coagulase Test Staphylococcus...

Introduction of MSA MSA stands for Mannitol Salt Agar and it is a selective, differential, and indicator medium that is used to isolate and identify S. aureus from the clinical specimens. Other Staphylococcus species and Micrococcus also grow on this medium. Selective due to is very high salt (7.5%) compared with other media Gram-Positive Staphylococcus: not fermenting mannitol, the medium does not change color (e.g.  epidermidis whereas Staphylococcus aureus yellow color colonies) Gram-Positive Streptococcus: No growth and also Gram-Negative: No growth Differential due to mannitol (sugar)fermentation (whenever sugar is fermented...