Modified oxidase test (microdase) is recommended for Gram-positive, catalase-positive cocci, only. The microdase test is a rapid method to differentiate Staphylococcus from Micrococcus by detection of the enzyme oxidase. Filter paper disks impregnated with tetramethyl-p-phenylenediamine […]
Hippurate is the glycine conjugate of benzoic acid. When hippurate is hydrolysed by an organism glycine and benzoic acid are formed. In the classical test (48 hours), The benzoic acid produced was detected using ferric […]
Bile-esculin test is widely used to differentiate Enterococci and Non-enterococcus group D streptococci, which are bile tolerant and can hydrolyze esculin to esculetin, from non-group D viridans group streptococci, which grow poorly on bile. […]
Salt Tolerance Test is used in the identification of enterococcal group D Streptococcus on the basis of their salt tolerance. The ability of the bacteria to grow in the presence of variable amount of Sodium […]
Pyrrolidonyl Arylamidase (PYR) test is a rapid test which is used for the presumptive identification of group A beta-hemolytic Streptococci and Enterococci. PYR test is available in different format. Original PYR test used to take […]
Catalase is an enzyme, which is produced by microorganisms that live in oxygenated environments to neutralize toxic forms of oxygen metabolites; H2O2. The catalase enzyme neutralizes the bactericidal effects of hydrogen peroxide and protects them. […]
Novobiocin test is used to differentiate coagulase-negative staphylococci (CONS) and presumptively identify the isolate as Staphylococcus saprophyticus (novobiocin resistant). It is usually performed on urine isolates (isolated from women of reproductive age groups) that are […]
Streptococcus pneumoniae strains are sensitive to the chemical optochin (ethylhydrocupreine hydrochloride). Optochin sensitivity allows for the presumptive identification of alpha-hemolytic streptococci as S. pneumoniae, although some pneumococcal strains are optochin-resistant. Other alpha-hemolytic streptococcal species are […]
The bile (sodium deoxycholate) solubility test distinguishes Streptococcus pneumoniae from all other alpha-hemolytic streptococci. Streptococcus pneumoniae is bile soluble whereas all other alpha-hemolytic streptococci are bile resistant. Sodium deoxycholate (2% in water) will lyse the […]
Bacitracin is a bactericidal drug useful in the treatment of superficial skin infections but too toxic for systemic use. Bacitracin is a polypeptide antibiotic produced by Bacillus subtilis. This drug interferes in the peptidoglycan synthesis […]
Coagulase test is used to differentiate Staphylococcus aureus (positive) from Coagulase Negative Staphylococcus (CONS). Coagulase is an enzyme produced by S. aureus that converts (soluble) fibrinogen in plasma to (insoluble) fibrin. Staphylococcus aureus produces two […]
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