Shigella

Shigella is a genus of bacteria that is Gram-negative, non-spore-forming, rod-shaped, and closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and gorillas. During infection, it typically causes dysentery.

Classification

Shigella species are classified by three serogroups and one serotype:

• Shigella dysenteriae (group A)
• Shigella flexneri (group B)
• Shigella boydii (group C)
• Shigella sonnei (group D)

Pathogenesis

Shigella infection is typically via ingestion (fecal–oral contamination); depending on age and condition of the host, fewer than 100 bacterial cells can be enough to cause an infection. Shigella uses a type-III secretion system, which acts as a biological syringe to translocate toxic effector proteins to the target human cell.

Symptoms

Symptoms may range from mild abdominal discomfort to full-blown dysentery characterized by cramps, diarrhea, with slimy, bloody stools, fever, and vomiting. Symptoms typically appear 1–2 days after exposure, and recovery occurs in 5–7 days. In some cases, individuals may develop hemolytic uremic syndrome (HUS) leading to kidney failure.

Treatment

Shigella infection is typically self-limiting, and in most cases, antibiotic treatment is not required. However, when necessary, antibiotics can be used. Resistance to antibiotics is common, so testing to determine which antibiotics will work is often needed.

Prevention

Prevention of shigellosis is through good hand hygiene and avoidance of food and water contaminated with fecal material.

See also

• List of bacterial genera named after personal names
• Pathogenic bacteria

Shigella

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  Shigella stool