Shigella

Shigels are divided into 4 subgroups:


 * A with the subspecies S. dysenteriae ,
 * B - S. flexneri ,
 * C - S. boydii ,
 * D - S. sonnei.

They are the least chemically active of all enterobacteria.

Antigenic structure
The above 4 species can be differentiated into 38 different antigenic structures (except S. sonnei, which occurs in only one serotype).

Pathogenicity

 * Entrance gate: oral cavity.
 * Reproduction in the small intestine.
 * Transition to the colon and the epithelium that destroys it. Shigel penetration into epithelial cells is encoded by a large plasmid, which has also been found in enteroinvasive E. coli . The plasmid encodes the structure of outer membrane proteins that allow the microorganism to bind to the microvilli and initiate microbe-induced phagocytosis.
 * The virulent type of S. dysenteriae forms a Shiga toxin that causes paralysis in small animals. It interferes with the proteosynthesis of sensitive cells and kills them.

Epidemiology

 * The most affected are children from 6 months to 10 years.
 * Adults get sick most often as a result of contact with sick children.
 * Epidemics are affecting facilities where hygiene standards are difficult to maintain.
 * The rapid spread is caused by the high infectivity of the germs and the fact that less than 200 bacteria can cause the disease.
 * The current pandemic strain - resistant to sulfonamides, tetracyclines , chloramphenicol , ampicillin and trimethoprim - has very few treatment options.

Clinical picture
Shigella dysenteriae in the stool of a patient with shigeliosis
 * The incubation period is 1-4 days.
 * Clinical signs of bacillary dysentery: fever, painful urge, high frequency of stools with mucus and blood. The infection lasts 2-3 days.

Laboratory diagnostics

 * Cultivation of stool samples on Endo agar or DC agar . It is also possible to use chromogenic agars or XLD (xylose-lysine deoxycholate) agar, on which we detect lactose fermentation and H 2 S formation.
 * Serotyping of suspect strains.

Therapy

 * In the uncomplicated course, symptomatic treatment (adherence to diet and intestinal antiseptics).
 * The use of ATB is unavoidable only for young children and the elderly. ATB prevents the spread to deeper layers of the mucosa.

Prevention

 * Hygiene and hand washing.

related articles

 * Shigellosis
 * intestinal infectious diseases : Cholera ▪ Typhoid fever ▪ Paratyphoid ▪ Salmonella enteritis ▪ Campylobacter enteritis ▪ Cryptosporidiosis ▪ Rotavirus enteritis ▪ Adenovirus enteritis

Reference

 * 1) BENEŠ, Jiří. Infectious medicine. 1st edition edition. Galén, 2009. 651 pp. 234–235. ISBN 978-80-7262-644-1.
 * 2) ↑Jump up to:a b c GOERING, Richard V and Hazel M DOCKRELL. Mims' medical microbiology. 5th edition. Prague: Triton, 2016. 568 pp. 283.  ISBN 978-80-7387-928-0.