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 […]
Principle: 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 […]
Citrate utilization test is commonly employed as part of a group of tests, the IMViC (Indole, Methyl Red, VP and Citrate) tests, that distinguish between members of the Enterobacteriaceae family based on their metabolic by-products. Citrate […]
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 […]
In this blog post, i am sharing information about common, conventional biochemical tests and their primary uses in Microbiology laboratory for the identification of particular pathogen of interest. Some of the biochemical tests mentioned here […]
Colony color or pigmentation is mostly exploited characteristics of bacteria which aids in the differentiation and identification of the isolates. Except where, there is a growth of pigmented bacteria, the characteristics pigmentation observed in the […]
Salmonella is a Gram-negative, rod-shaped, motile bacilli which moves with the use of its peritrichous flagella. The genus Salmonella can be divided into two species (S. enterica and S. bongori), based on their phenotypic profile.The […]
Medium used for urease test: Any urea medium, agar or broth (It can be a sole medium or part of panel like motility indole urease (MIU) test) Indicator used in urease test: Phenol red Color change: […]
The oxidase test is used to identify bacteria that produce cytochrome c oxidase, an enzyme of the bacterial electron transport chain. When present, the cytochrome c oxidase oxidizes the reagent (tetramethyl-p-phenylenediamine) to (indophenols) purple color […]
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 […]
Indole test is used to determine the ability of an organism to split amino acid tryptophan to form the compound indole. Tryptophan is hydrolysed by tryptophanase to produce three possible end products – one of which […]
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