Shigella flexneri

Shigella flexneri are Gram-negative bacteria that cause bacillary dysentery (shigellosis) in humans, and result in over 100 million episodes of diarrhea and millions of deaths each year. Shigellosis arises due to poor sanitation and hygiene, and is transmitted by the oral-faecal route. Antibiotic therapy is frequently ineffective due to multi-antibiotic resistance. Shigellae are facultative intracellular pathogens able to invade, replicate within, and kill intestinal cells, and can also spread from cell to cell without going through an extracellular stage. The infection results in an acute inflammatory response in the colon that causes the majority of the disease symptoms. S. flexneri bacteria are able to invade intestinal cells and replicate within them. After escaping into the cytosol, they replicate and exhibit intracellular motility in which the polarly localized cell surface protein IcsA recruits host proteins to generate actin-based motility (ABM). ABM allows the bacteria to spread from cell to cell thereby creating a focus of infection. 

Shigella flexneri infected HeLa cells