SHIGELLA

Shigellae were among the first organisms to be shown in the 1950s to harbor transferable antibiotic resistance determinants on conjugative plasmids. In developing countries, rates of multiple resistance are high, with >50% of isolates resistant to ampicillin, chloramphenicol, tetracycline, co-trimoxazole or nalidixic acid. In the last few years, fluoroquinolone resistance in Shigella spp. increased in the Indian subcontinent as a result of both gyrA and parC mutations, compromising the use of fluoroquinolones as the first line of treatment for dysentery in that region. Multiresistance is most common in Shigella dysenteriae, followed by Shigella flexneri and Shigella sonnei. In developed countries rates of resistance are higher in shigellosis patients with a history of travel abroad.