General Microbiology

Types of microscopy used in bacteriology Light microscopy Phase contrast microscopy Fluorescence microscopy Darkfield microscopy Transmission electron microscopy Scanning electron microscopy Fluorescent microscopy in which ultraviolet rays are used to examine cells after treatment with fluorescent days. Phase contrast microscope enhances the refractive index differences of the cell components. This microscopy can be used to reveal details of the intern…

NON-SPECIFIC KILLER CELLS Several different cells including NK and LAK cells, K cells, activated macrophages and eosinophils are capable of killing foreign and altered self target cells in a non-specific manner. These cells play an important role in the innate immune system. A. NK and LAK cells Natural killer (NK) cells are also known as large granular lymphocytes (LGL) because they resemble lymphocytes in their morphology, except that they are slightly lar…

Radioimmunoassays (RIA) It is an extremely sensitive technique in which antibody or antigen is labelled with a radioactive material. The amount of radioactive material in the antigen-antibody complex can be measured with which concentration of antigen or antibody can be assayed. After the reaction ‘free’ and ‘bound’ fractions of antigen are separated and their radioactivity-measured.  …

Measurement of Bacterial of Growth A convenient method is to determine turbidity by photoelectric colorimeter or spectrophotometer.  The cell number can be counted as total cell number as well as viable count. Viable Count Viable number of bacteria can be counted by inoculating the suspension onto solid growth medium and counting the number of colonies. Since each colony is the end product of one viable bacterium, their count gives the number of viable bact…

Application of agglutination reactions Agglutination reaction                Example Tube agglutination    -> Widal test, Weil Felix reaction, Standard tube test for brucellosis Slide agglutination   -> Typing of pneumococci,Diagnosis of Salmonella,Diagnosis of Shigella Agglutination Absorption test  -> Salmonella diagnosis Coagglutination &nbs…