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Introduction of Shigella Serotyping Shigella Serotyping helps to differentiate serotypes of Shigella. Serotypes refer to separate groups within a species of microorganisms that all share a similar property. More specifically, each serotype has the same number of antigens on its surfaces. For example, Shigella flexneri serotype 1, 2, 2a, S. sonnei, and S. …
Introduction of XLD Agar XLD agar is a selective, differential, and indicator medium for the isolation of enteric pathogens. XLD stands for xylose lysine deoxycholate. It also supports the growth of more fastidious enteric organisms. XLD agar was developed by Taylor. It was specially designed to allow the …
Introduction of Shigella flexneri Shigella are Gram-negative bacilli measuring about 1-3 µm X 0.5 µm. They are non-motile, non-encapsulated, non-sporing, and non-acid-fast bacteria belonging to the family Enterobacteriaceae. They cause an infectious disease called Shigellosis. There are four species or serogroups based on biochemical and …
Introduction of Exotoxins and Endotoxins Numerous bacteria produce toxins, enzymes, and pigments. Toxins and enzymes play significant roles in pathogenicity. Toxins are of two types- Differences Between Exotoxins and Endotoxins The differences between exotoxins and endotoxins are as follows- S. No Exotoxins Endotoxins 1. Exotoxins …
Introduction of Enterobacteriaceae The family Enterobacteriaceae was first proposed by Rahn in 1936 and it is a very large group of gram-negative bacteria that possess a number of common morphological and biochemical properties and similar DNA base compositions. The widely used systems for the classification …
Introduction of LF and NLF Gram-Negative Bacteria on MacConkey Medium MacConkey agar/ medium is recommended for use as a selective, differential, and indicator growth medium for the isolation of gram-negative bacilli including coliform organisms and enteric pathogens, on the basis of lactose fermentation. Peptones (meat …
Introduction of Amoebic dysentery and Bacillary dysentery Amoebic dysentery or amoebiasis is an intestinal infection caused by a unicellular (protozoan) parasite, Entamoeba histolytica whereas bacillary dysentery or shigellosis is a bacterial disease caused by a group of non-motile bacteria called Shigella species. Differences between Amoebic …