Salmonella, Shigella, and yersinia

Abstract

Salmonella, Shigella, and Yersinia cause a well-characterized spectrum of disease in humans, ranging from asymptomatic carriage to hemorrhagic colitis and fatal typhoidal fever. These pathogens are responsible for millions of cases of food-borne illness in the United States each year, with substantial costs measured in hospitalizations and lost productivity. In the developing world, illness caused by these pathogens is not only more prevalent but also associated with a greater case-fatality rate. Classic methods for identification rely on selective media and serology, but newer methods based on mass spectrometry and polymerase chain reaction show great promise for routine clinical testing.

Keywords: Enteric; Gastroenteritis; Gram-negative bacilli; Salmonella; Shigella; Yersinia.

Figure 1

Relationships within the Salmonella genus, including species, subspecies, and serovar designations are illustrated. Note that serovars do not have official taxonomic status. Four representative serovars are shown for S. enterica subsp. enterica. Only the most common typhyoidal serovars, and representative non-typhoidal serovars are shown. There are greater than 2500 serovars in total, with the most common disease-causing serovars belonging to S. enterica subsp. Enterica.

Figure 2

Key for differentiation of Shigella, enteroinvasive Escherichia coli (EIEC), and noninvasive Escherichia coli. (From van den Beld MJ, Reubsaet FA. Differentiation between Shigella, enteroinvasive Escherichia coli (EIEC) and noninvasive Escherichia coli. European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology 2012;31(6):899–904; with permission)

1. Based on Edwards and Ewing’s identification of Enterobacteriaceae, 4^th edition, 1986 and/or Cowan and Steel’s manual for the identification of medical bacteria, 3^rd edition, 1993.

2. Performed with a standard PCR protocol, with primers designed to amplify a part of the conserved region of ipaH_7.8, as described by Buysse et al., Microb. Pathog. 19(5):335–349.

3. Incubated for 24 h in BHI-medium at 37°C.

4. Known O:H serotypes of EIEC according to Bergey’s manual of Systematic Bacteriology, 2^nd edition, volume 2, The Proteobacteria, Part B The Gammaproteobacteria.