MBIO 3470 Lecture 26: Salmonella & Shigella
20 Mar 2018
School
Department
Course
Professor
Document Summary
Members of the genus salmonella produce significant infections in humans and in certain animals. The cells are gram negative, facultative anaerobic rods that morphologically resemble other enteric bacteria. On selective mediate used primarily to isolate enteric pathogens, salmonella produce clear, colorless, non-lactose fermenting colonies. Colonies with black centers are seen if the media contain indicators for h2s production. The biochemical features for the genus: do not ferment lactose, negative for indole, the voges-proskauer test, phenylalanine and urease, most produce hydrogen sulfide on triple sugar iron agar, do not grown in potassium cyanide. Classification: until recently, the genus salmonella included 3 biochemically discrete species: s. enteritidis, s. choleraesuis and s. typhi. Genetic studies indicated that bacterial species in salmonella are very closely related and only 1 species, s. enterica must be designated. Additional changes in the salmonella classification include the classification of the genus into 7 subgroups with designated subspecies.
