Shigella flexneri serotype 2a (S. flexneri 2a) (S. flexneri 2a)

Shigella flexneri serotype 2a is a Gram-negative bacterial pathogen and the primary cause of endemic shigellosis (bacillary dysentery), particularly in low- and middle-income countries [11][14]. It is characterized by its high infectivity and ability to survive the acidic environment of the stomach to reach and invade the colonic mucosa [2][11]. The pathogen utilizes a Type III secretion system (T3SS) to deliver virulence effectors into host epithelial cells, promoting bacterial entry and subsequent inflammatory destruction of the tissue [2][13]. Once intracellular, S. flexneri 2a exploits the host's actin machinery via the IcsA (VirG) protein to move and spread between cells, a process that can be modulated by host-cell kinases like Bruton's tyrosine kinase (Btk) [8][13]. While standard treatment involves antibiotics like ciprofloxacin and azithromycin, the rise of multidrug-resistant (MDR) strains has driven the development of new vaccines and host-directed therapies [1][12]. Current research focuses on O-antigen conjugate vaccines and small molecule inhibitors that target either essential bacterial enzymes or the host pathways required for bacterial dissemination [10][13].

Other names

Shigella flexneri 2aShigella flexneri strain 301S. flexneri 2aShigella flexneri serotype 2a strain 301

Antibiotics targeting this pathogen act through various mechanisms: fluoroquinolones (e.g., ciprofloxacin) inhibit bacterial DNA gyrase and topoisomerase IV [6][7]; macrolides (e.g., azithromycin) inhibit protein synthesis by binding the 50S ribosomal subunit [4][7]; and cephalosporins (e.g., ceftriaxone) inhibit cell wall synthesis. Experimental host-directed therapies, such as the Btk inhibitor ibrutinib, target host signaling pathways to impair bacterial cell-to-cell spread [13]. Vaccines primarily target the O-antigen to induce serotype-specific protective immunity [10][15].