<prompt> Which stain is used for Corynebacterium diphtheriae -GeimsaAlbertPASIndia ink  <response>: Ans. is b i.e., Albert The diphtheria bacillus was first observed and described by Klebs 1883 but was first cultivated by Loeffler 1884. Therefore, it is known as Klebs - Loeffler bacillus KLB. Corynebacterium diphtheria is gram positive slender rod bacilli which is noncapsulated and non-motile. The bacilli are arranged in a characteristic fashion in smears, being at various angles to each other, resembling the letter V or L - Chinese letter or cuneiform arrangement. There is chracteristic Clubbed appearance. Characteristic feature is irregular staining due to presence of granules, called Babes Ernest or volutin granules. These granules are also called metachromatic granules or polar bodies. These granules are composed of polymetaphosphate. Volutin granules are usually stained with Loefflers methylene blue or toluidine blue and appear reddish violet. Special stains for volutin granules are Ponders stain, Alberts stain and Neissers stain. 