Principle Citrate utilisation test is used to detect the ability of an organism to utilize sodium citratre as a sole source of carbon and ammonium salt as a sole source of nitrogen. Bacteria that grow in the medium turn the medium alkaline. This is indicated by the change of color of bromothymol blue indicator from […]
Coagulase test is done to distinguish Staphylococcus aureus from other Coagulase negative Staphylococci (CONS) like Staphylococcus epidermidis, Staphylococcus saprophyticus etc. Staphylococcus aureus produces two types of coagulase, i.e. free coagulase and bound coagulase. Free coagulase is an extracellular enzyme that can be detected in tube coagulase test while bound coagulase is a cell wall associated protein […]
Principle: Catalase test is done to check for the presence of enzyme catalase in bacteria that hydrolyzes hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). If the bacteria possess catalase enzyme, it’s evident by formation of bubbles in the test due to liberation of oxygen. Lack of catalase is indicated by absence of bubble production. […]
Bacteria have to be grown for their identification and investigating other properties like antimicrobial susceptibility, test for enzyme production or test for virulent genes etc. By the use of appropriate method of isolation in culture medium, they can be obtained in pure cultures for further study. Numerous and diverse type of culture medium are available […]
Smear preparation for AFB: Take a grease free scratch free glass slide to prepare the smear. (A new glass slide should be used for smear preparation, if greasy; you can clean the grease by wiping it with alcohol and use it after its air dry). Label the slide with laboratory code and serial number with […]
First of all, prepare a smear and let it air dry. Fix the smear with heat rolling the slide over blue flame for three times. Pour crystal violet over the smear and wait for 1 minute. Drain off excess stain and wash the stain with distilled water. Pour iodine over the stained smear and wait […]