Question

Which of the following is false concerning Salmonella and Shigella? A. Shigella are H2S + and motile, Salmonella are H2S - and nonmotile. B. Salmonella Typhi causes typhoid fever with serious systemic spread. C. Shigella cause bacillary dysentery. D. There is a capsule and an attenuated living vaccine for typhoid fever. E. Shigella dysenteriae produces the most severe form of shigellosis and may lead to HUS and kidney damage due to production of Shiga toxin.

Answer 1

Answer:

A. Shigella are H2S + and motile, Salmonella are H2S - and nonmotile

Explanation:

Shigella is a genus of Gram-negative (i.e.,  they have a cell wall composed of a thin layer of peptidoglycan), nonmotile, and facultative anaerobic bacteria; whereas Salmonella species are Gram-negative and facultative anaerobic bacteria. Moreover, Salmonella are motile bacteria, in a similar way to other human pathogenic bacteria (e.g., Vibrio cholerae, Pseudomonas aeruginosa, and E. coli). Salmonella can produce hydrogen sulfide (H2S) from thiosulfate or sulfite; whereas Shigella species are unable to produce hydrogen sulfide. Typhoid fever, also known as enteric fever, is an infection caused by S. typhi that can spread throughout the body and affect different organs (i.e., it is a multisystemic illness). Vivotif (Typhoid Vaccine Live Oral Ty21a) is a live attenuated bacterial vaccine used for oral administration only; whereas Vi capsular polysaccharide vaccine (ViCPS) is a vaccine administered by injection. Finally, shigellosis is an infection that affects the digestive system caused by Shigella bacteria. In this regard, S. dysenteriae produces a potent cytotoxin known as 'Shiga toxin' that may cause local destruction of the colonic epithelium.