Microbiology

Introduction Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates. Staphylococcus aureus is known to produce coagulase, which can clot plama into gel in tube or agglutinate cocci in slide. This test is useful in differentiating S.aureus from other coagulase-negative staphylococci. Most strains of S.aureus … Read more

Introduction A germ tube test is a diagnostic test in which a sample of fungal spores are suspended in animal serum and examined by microscopy for the detection of any germ tubes. It is particularly indicated for colonies of white or cream color on fungal culture, where a positive germ tube test is strongly indicative of Candida albicans. Germ tube formation was first reported by Reynolds … Read more

Introduction Voges–Proskauer commonly VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth which has been inoculated with bacteria. A cherry red color indicates a positive result, while a yellow-brown color indicates a negative result.The test depends on the digestion of glucose to acetylmethylcarbinol. In the presence of oxygen and strong … Read more

Introduction Negative staining is one of electron staining techniques. In Negative staining technique, an acidic stain such as Nigrosin, India ink, Eosin or Congo red is used in which the bacterial culture or the specimen is mixed well and then spread over the Microscopic glass slide to form a thin smear.This technique leaves heavy metals … Read more

Introduction The name Mueller Hinton agar(MHA) is derived from the names of co-developers, microbiologist John Howard Mueller and veterinary scientist Jane Hilton at Harvard University who first published the method in 1941. This Mueller Hinton agar (MHA) was a protein-free medium for isolating the pathogenic strains of Neisseria. Later in 1966, Muller Hinton agar (MHA) was adopted as the common … Read more

Introduction Sabouraud agar or Sabouraud dextrose agar (SDA) is a selective medium for fungal culture and primarily used for the isolation of Dermatophytes, Yeasts and various other Pathogenic and Non- pathogenic fungi as well as it also supports the growth of Nocardia spp. and other filamentous bacteria. Moreover, the slightly acidic pH of this SDA medium inhibits the growth of … Read more

Introduction Trypticase soy agar or tryptone soya agar (TSA) and Trypticase soy broth or tryptone soya broth (TSB) with agar are growth media for the culturing of bacteria. They are general-purpose, nonselective media providing enough nutrients to allow for a wide variety of microorganisms to grow. They are used for a wide range of applications, including culture storage, enumeration of cells (counting), isolation of pure cultures, or simply general culture. Principle … Read more

Introduction Eosin-methylene blue (EMB) agar was initially formulated in 1916 by Holt-Harris and Teague, to visibly differentiate between the lactose fermenting and non-fermenting microorganisms through the use of eosin and methylene blue dyes. The medium also included sucrose to differentiate between coliforms that were able to ferment sucrose more rapidly than lactose and those that … Read more

Introduction Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria.It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C.The name is itself derived from the fact that red blood cell (RBC) lysis gives the medium a chocolate-brown color.  Chocolate agar is used for growing fastidious respiratory … Read more