Characterization of Adhesion and Invasion Virulence Factors in Streptococcus Pneumoniae, Shigella, and Salmonella Species Isolated from Ethiopian Patients
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Date
2001-06
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Addis Ababa University
Abstract
Pathogenic bacteria have multiple vilUlence factors that act in conceit to cause damaging
effects in the host body. In this work few of the vil1llence factors interactions between
pathogenic bacteria and human epithelial cells have been studied. Therefore, tissue
adherence and invasion as well as haemagglutinating abilities of 50 strains of
Streptococcus pl/eumol/iae, 25 Shigella spp. and 25 Salmol/ella spp. isolated fi'om patients
were studied.
The tissue adherence ability of these bacterial isolates was detected using cultured human
epithelial cells (HEp-2 cells). In addition to the tissue adherence assay agglutination
ability of the bacteria against six elythrocyte types was tested to find out if the same
factors are involved in haemagglutination and adhesion to HEp-2 cells. The results of
these tests showed that haemagglutination and tissue adherence abilities of the pathogenic
bacteria are different. All Salmol/ella and Shigella isolates except one had adherence
ability to HEp-2 cells. Unlike their adherence ability to HEp-2 cells, the
haemagglutination result showed that only 13 strains of the Salmol/ella spp. and 17 strains
of the Shighella spp. are haemagglutinating. Similarly, 43 (86%) of Streptococcus
pllelllllolliae were able to adhere to HEp-2 cells and among these only 9 strains showed
non-haemagglutinating ability. In the s. pl/eulllol/iae isolates, there were 6 strains that do
not adhere to HEp-2 cells, and one was found to be neither haemagglutinating nor
adhering to HEp-2 cells.
The tissue invasion ability of the pathogenic bacteria was detelmined with a factor of2-In'
intracellular growth incubation time and addition of exogenous gentamicin. The
mvas\Veness ability of each strain was detennined as percentage of bacteria recovered
from initial inoculum quantity of bacteria added to HEp-2 cell monolayer. From the
invasiveness results all the Shigella and Salmol/ella isolates were able to invade the
cultured epithelial cells with invasion results ranging between 1.26 and 32.93 %. In the
case of Streptococcus pllelllllOl/iae isolates, only 12 out of the 50 strains were able to
invade the cultured HEp-2 cells with invasion percentages ranging between 0.04 and
2.11 %. The remaining 38 strains could not invade the HEp-2 cells
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Biology