Shigella
| Shigella | |
| Enterobacteriaceae | |
| Shigella | |
| Shigella - Gram stain. | |
| Morphology | Good bar |
|---|---|
| Relation to oxygen | facultatively anaerobic |
| Cultivation | blood agar , lactose agar |
| Antigens | 38 antigenic structures |
| Virulence factors | Shiga toxin |
| Source | human - an exclusively human pathogen |
| Transmission | alimentary, fecal-oral route |
| Incubation time | 1-4 days |
| Disease | bacterial dysentery, shigellosis |
| Diagnostics | stool cultivation |
| Therapy | diet, antiseptics, etc. ( cotrimoxazole , azithromycin , ciprofloxacin ) |
| MeSH ID | D012760 |
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
- The incubation period is 1-4 days.
Shigella dysenteriae in the stool of a patient with shigeliosis
- Clinical signs of bacillary dysentery: fever, painful urge, high frequency of stools with mucus and blood. The infection lasts 2-3 days.
- Cultivation
-
Cultivation of Shigella flexneri on deoxycholate-citrate agar -
Shigella flexneri - Blood agar -
Cultivation of Shigella flexneri on Endo's soil
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.
Links
related articles
- Shigellosis
- intestinal infectious diseases : Cholera ▪ Typhoid fever ▪ Paratyphoid ▪ Salmonella enteritis ▪ Campylobacter enteritis ▪ Cryptosporidiosis ▪ Rotavirus enteritis ▪ Adenovirus enteritis
References
- HORACEK, Jiri. Basics of medical microbiology. 1st edition. Prague: Karolinum Publishing House, 2000. vol. 1. ISBN 80-246-0006-4. .
- GOERING, Richard V and Hazel M DOCKRELL. Mims' medical microbiology. 5th edition. Prague: Triton, 2016. 568 pp. ISBN 978-80-7387-928-0 .
Reference
- BENEŠ, Jiří. Infectious medicine. 1st edition edition. Galén, 2009. 651 pp. 234–235. ISBN 978-80-7262-644-1 .
- ↑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 .
