Phage typing is useful in classification of all except:
Correct Answer: Streptococcus
Description: Ans: B (Streptococcus) Ref: Ananthanarayan R, Paniker CKJ. Textbook of Microbiology. 8th Edition. Hyderabad: Universities Press: 2009. Pg. 199. 205, 293-8, 305Explanation:StaphylococcusStaphylococci may be typed, based on their susceptibility to bacteriophagesAn internationally accepted set of phages is used for typing.Staphylococcal phage typing is done by a pattern method.The phage type of the strain is expressed by the designations of all the phages that lyse it. Thus, if a strain is lysed only by phages 52 79 and 80, it is called phage type 52/79/80.Phage typing is of great importance in epidemiological studies of staphylococcal infections.StreptococcusThe Streptococcus are classified on the basis of their hemolytic properties as alpha, beta and gamma groupsBeta hemolytic streptococci were classified by Lancefield serologically into groups based on the nature of a carbohydrate (C) antigen on the cell wall.These are known as Lancefield groups, twenty of which have been identified so far and named A-V (without I and J).Vibrio choleraeThe El Tor strains are differentiated from Classical strains of Vibrio cholerae based on nonhemolytic nature, negative VP tests, chick cell agglutination, polymyxin sensitivity and phage susceptibility testsSalmonellaImportant pathogens such as S tvphi, S paratyphi A and B. and S typhimurium can he further typed for epidemiological purposes by phage susceptibilityIntraspecies classification of S typhi for epidemiological purposes was made possible by bacteriophage typing, first developed by Craigie and Yen (1937). They found that a bacteriophage acting on the Vi antigen of the typhoid bacillus (Vi phage II) was highly adaptable. The parent phage is called phage A. It could be made specific for a particular strain of typhoid bacillus by serial propagation in the strain.Phage typing also provides information on the trends and patterns in the epidemiology of typhoid at the local, national and international levels.The phage type is stable.
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