Gram stain: negative Cell shape: bacillus Arrangement: Oxygen requirements: facultative anaerobe Motility: non-motile Other: There are actually four different species in this genus. They are non-lactose fermenters.
Habitat: Found only in the intestinal tract of humans, apes and monkeys.
Pathogenicity: Causes "bacillary dysentery" or "shigellosis"; second only to E. coli as a cause of traveler's diarrhea. Bacteria not affected by stomach acidity and pass to small intestine where they proliferate. They travel on to the large intestine where the damage to host is done. The bacteria enter the cells of the mucosa and destroy them, causing severe diarrhea with blood, mucous, and pus in the stool; fever; vomiting. Some strains produce a powerful toxin called the "Shiga Toxin" that may lead to kidney failure and death.
Diagnosis is based on recovery of microbes from rectal swabs.
Transmission: fecal-oral route; highly communicable - ingestion of as few as 100 organisms can initiate infection.
Treatment: fluid and electrolyte replacement with fluoroquinolones or ampicillin.
*Actually use host cells' actin filaments to form a "tail" to push from one cell to another.
Shigella spp.
