Table 2

Enterotoxin activity of S. flexneri strains as measured in Ussing chamber assay*

StrainEnterotoxin producedΔIscP vs. 2457T
2457T (ΔcadA)ShET1; ShET2103.0  ±  19.0
BS103 (ΔcadA)ShET178.1  ±  3.03not significant
BS529 (pCADA+)ShET1; ShET233.8  ±  13.10.04
2457T + BS529ShET1; ShET256.0  ±  12.30.02
2457T + BS529§ShET1; ShET219.5  ±  4.30.0013
  • * Variations in transepithelial electrical PD, Isc, and total tissue resistance were recorded 120 min after addition of supernatants to chamber. PD measures the difference in electrical charges between the mucosal and serosal sides of the tissue and is generated by differences in concentrations of ions. Isc is the amount of current necessary to nullify the PD. Increase of both PD and Isc induced by enterotoxins reflects C1 secretion and is indicative of a diarrhoegenic effect. 

  • Unpaired Student’s t test. 

  • ΔIsc measured 60 min after addition of supernatants to chamber. 

  • § ΔIsc measured 120 min after addition of supernatants to chamber.