Various
virulence factors including invasion, adhesion, cytotoxicity, protease, lipase,
elastase, urease production and swarming migration were determined for 24 Proteus
isolates recovered from clinical specimens. The results showed that the distribution
of virulence factors was different among the test isolates and strain specific in
most cases. All Proteus isolates showed invasion and adhesion capabilities
with different extents. In addition, they were able to produce elastase, urease
and exhibit swarming activity. Protease and lipase activities were not detected
in any of the isolates. High
cytotoxicity was demonstrated in all isolates. A
parallel correlation between invasion and cytotoxicity was demonstrated in all
isolates. Five isolates of high virulence factors productivities
were selected and identified by Analytical
Profile Index as Proteus mirabilis (Pr2, Pr12 and Pr24) and Proteus penneri (Pr6 and Pr20).
Plasmid curing by acridine
orange resulted in the loss of invasiveness
and adhesion capabilities of the five
isolates, while other virulence factors levels showed no significant
difference changes. The results give a clear evidence that both invasion and
adhesion of the tested Proteus isolates are plasmid rather than
chromosomally encoded.