Shigella dysenteriae
Shigella dysenteriae
Shigella dysenteriae is a non-spore -forming, Gram- negative, rod-shaped, facultative anaerobic and non - Portable bacterium. It is named after its discoverer, the Japanese microbiologist Kiyoshi Shiga, and diarrhea occur as the main symptom of infection ( dysentery ). Genetically, morphologically and physiologically it is closely related to Escherichia coli.
Shigella dysenteriae is primarily for humans, usually pathogenic and caused mainly abdominal pain and diarrhea. The most common route of infection is the intake via contaminated food, in particular through feces -contaminated drinking water.
Properties
Morphology and physiology
Shigella dysenteriae is a Gram-negative facultative and anaerobic bacteria. The cells are rod-shaped. Shigella dysenteriae does not form spores and is closely related to Escherichia coli. Both species belong to the family of Enterobacteriaceae, which also includes the Yersinia, the Klebsiella and Citrobacter species belong, and are very similar morphologically and physiologically. By some biochemical tests, they are distinguishable. So Shigella dysenteriae can, in contrast to Escherichia coli lactose not degrade further features Shigella do not have a decarboxylase for degradation of lysine. Also be on serological methods differ in both species.
Proof
The clinical detection of Shigella dysenteriae is made by microscopic examination of a stool sample and enrichment culture with selective media. The identification is possible by means of biochemical tests or by means of specific antibodies, as well as a detection means of the polymerase chain reaction ( PCR) and subsequent hybridization with specific DNA probes. Shigella can survive on toilet seats for 14 days. A stool sample should, however, be processed within three hours. As an alternative, therefore, lends itself to a rectal swab.
Pathogenicity
Ten to 200 seeds are sufficient for infection by Shigella dysenteriae, which is also referred to as shigellosis or Shigellosis. The main symptoms are crampy abdominal pain, sudden onset of high fever and diarrhea, and occasionally vomiting. The main reason for these symptoms are produced by the bacteria Shigella enterotoxins. Shiga toxin, formed by some enterohemorrhagic Escherichia coli, in addition means that the feces are excreted bluthaltig in about 70 percent of cases. In particular, for children therefore experience a hemolytic uremic syndrome. The incubation period until the onset of symptoms is usually one to two days, the duration of an untreated infection five to seven days. Epidemics can occur in regions with poor hygiene and inadequate medical care. The mortality rate is then approximately five to 15 percent.
Especially among children and the elderly to infection is often in need of treatment. Antibiotic therapy is usually with ciprofloxacin and ampicillin. Event of serious fluid loss (dehydration ) due to diarrhea orally or intravenously electrolyte-containing liquids are fed beyond. For prevention, especially since they comply with hygiene rules and the proper preparation and storage of food is necessary.
The suspicion of an infection with Shigella dysenteriae and confirmed cases of illness, deaths and chronic carriers are notifiable in Germany after the Infection Protection Act.