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3 Cards in this Set
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Clinical classification Typhoidal salmonella ie S typhi and Paratyphi Restricted to human hosts Non typhoidal salmonella Colonize intestines of animals Antigenic structure Somatic antigen O Flagella antigen H Surface antigen, Vi in some species Fimbrial antigens in other strains O antigen Somatic Part of LPS Heat stable Alcohol stable Formaldehyde labile Used in Widal test for s typhi Less immunogenic O antibody appears early, disappear early indicating recent infection Forms compact granular chalky clumps on reacting an antibody Agglutination takes place slow Optimum temperature for agglutination is 55 degrees Serogroups is based on O antigens Also called boivin antigen. Extracted by treatment with trichloroacetic acid
H antigen Flagella antigen Made up if flagellin Heat labile Alcohol labile Formaldehyde stable Used in Widal test for s typhi, Paratyphi A and B More immunogenic H antibody appears late, disappear late indicating convalescent stage Form large loose fluffy clumps on reacting antibody Agglutination takes place rapidly Optimum temperature for agglutination is 37 degrees Serogroups differentiated into serotypes using h antigens Are biphasic Vi antigen Surface polysaccharide envelope or capsular antigens Related to virulence Expressed in s typhi, Paratyphi. Citrobacter freundii Renders bacilli inagglutinable with O antiserum Agglutination after boiling, heating at 100 degrees for 1 hour removes Vi antigen Poorly immunogenic Antibody titres very low Not helpful in diagnosis Complete absence of vi antibody- poor prognosis Disappear early in convalescent Persist in carrier state Phage typing of s typhi using Vi specific bacteriophage Vi antigen used for vaccination Antigenic variation |
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