A major determinant in the virulence of @entity5746 and Shigella spp. is the ability of these organisms to invade epithelial cells of the @entity344 and multiply intracellularly. The invasion of cell culture monolayers is a convenient experimental system to evaluate eucaryotic cell penetration and is correlated with the potential of a strain to cause @entity1 disease. We have developed an agarose-L agar overlay technique which allows for the convenient quantitation of the number of infected tissue culture cells in a monolayer. Bacterial strains were introduced onto antibiotic-free HeLa cell monolayers. Infected monolayers were washed, and noninternalized bacteria were counterselected with @entity7913 (50 micrograms/ml). The number of infected HeLa cells present was determined by overlaying the monolayer with distilled water-agarose (0.5 to 1.5%) followed by an equal volume of 2X L agar. Bacterial colonies formed over infected cells in 24 h at 37 degrees C, and wells were counted with a dissecting microscope under X2 power. Bacterial colonies were not observed with noninvasive variants of Shigella spp. To obtain countable wells (20 to 200 CFU) the multiplicity of @entity281 or invasion times were adjusted. With a 90-min invasion time, the invasive potential of a strain was reflected by the multiplicity of @entity281 needed to produce countable wells. The quantitation of bacterium-invaded cells by using standard bacteriological methods is a convenient and rapid method to evaluate the invasive potential of bacterial strains. Additionally, parameters essential for the invasive process can easily be investigated.

Quantitation of HeLa cell monolayer invasion by Shigella and XXXX species.

@entity1 :: ('9606', 'Species') :: ['human'] @entity7913 :: ('MESH:D007612', 'Chemical') :: ['kanamycin'] @entity344 :: ('MESH:D005767', 'Disease') :: ['gastrointestinal mucosa'] @entity281 :: ('MESH:D007239', 'Disease') :: ['infection'] @entity5746 :: ('MESH:D012480', 'Disease') :: ['Salmonella']
@entity5746 :: (MESH:D012480,Disease) :: ['Salmonella']
