The normal chain length distribution of the O antigen is required for the interaction of Shigella flexneri 2a with polarized Caco-2 cells

Shigella flexneri causes bacillary dysentery in humans. Essential to the establishment of the disease is the invasion of the colonic epithelial cells. Here we investigated the role of the lipopolysaccharide (LPS) O antigen in the ability of S. flexneri to adhere to and invade polarized Caco-2 cells. The S. flexneri 2a O antigen has two preferred chain lengths: a short O antigen (S-OAg) regulated by the WzzB protein and a very long O antigen (VL-OAg) regulated by Wzz pHS2. Mutants with defined deletions of the genes required for O-antigen assembly and polymerization were constructed and assayed for their abilities to adhere to and enter cultured epithelial cells. The results show that both VL- and S-OAg are required for invasion through the basolateral cell membrane. In contrast, the absence of O antigen does not impair adhesion. Purified LPS does not act as a competitor for the invasion of Caco-2 cells by the wild-type strain, suggesting that LPS is not directly involved in the internalization process by epithelial cells.

Prolapso rectal en un recién nacido con diarrea por Shigella / Rectal prolapse in a neonate with Shigella diarrhea

Se describe un caso de prolapso rectal secundario a diarrea por Shigella en un neonato de 10 días de vida, alimentado con pecho exclusivo. Su hermano de 2 años había tenido diarrea por el mismo patógeno hasta 2 semanas antes. El coprocultivo fue positivo para Shigella flexneri II, resistente a amoxicilina; los hemocultivos y el cultivo de líquido cefalorraquídeo fueron negativos. El tratamiento con ceftriaxone por vía parenteral revirtió el prolapso en 48 h. Conclusión. El prolapso rectal es una complicación poco común de la diarrea por Shigella en la infancia. Se ha descripto en edades mayores, pero nunca antes en un neonato.

Shigella flexneri bacteremia in a child

We report an unusual and lethal case of Shigella flexneri septicemia in an 8-year-old Saudi handicapped child from a social home presenting with severe toxic megacolon and acute abdomen secondary to fulminant necrotizing enterocolitis

Shigella em alimentos / Shigella in the foods

Comenta-se nesta breve revisao a participacao e o significado de Shigella em processos de infeccao alimentar. Sao tambem abordados as caracteristicas do microrganismo, seus fatores de virulencia e determinancia genetica.Aspectos epidemiologicos da infeccao, bem como, condicoes de crescimento e metodos de deteccao em alimentos, sao tambem abordados

Molecular analysis of virulence plasmids of invasive shigella species

A total of 48 isolates of Shigella species obtained from the Military Central Laboratories was examined for serotype, antibiotic resistance and invasiveness. The transferability and molecular structure of the virulence plasmids from each isolate were also examined. Twenty strains were evasive and 70% of these virulent strains were multidrug resistant. Ten virulent strains [tra+] transferred ampicillin resistance and virulence simultaneously, i.e. they carried conjugative plasmids; while the other strains [10 strains] were tra-. By plasmid analysis and DNA homology, almost all the virulent strains carried a large plasmid of 230 Kb, and 2-3 small cryptic plasmids [6.4, 3.3 and 2.7 Kb]. The results suggested that the cryptic plasmids can be transferred to other strains of the same species by conjugation or mobilization, predicting that the virulent multidrug resistant strains may no longer be restricted to a narrow range of serotypes in the near future. Further genetic analysis of virulence plasmids may be essential for the development of recombinant vaccines against Shigella species

Susceptibilidad antimicrobiana de 561 cepas de shigella obtenidas de muestras clínicas / Antimicrobial susceptibility of 561 shigella strains from clinical samples

The study of susceptibility to 11 antimicrobial by agar difusion method of 561 Shigella strains at the Enteric Reference Laboratory of I.S.P., is informed. We found 18.7 percent of resistance, a lower value than the described in the literature of other countries