TABLE 1.

Bacterial strains used in this study

Straina	Description	Reference and source
PA103	Wild-type, cytotoxic isolate	22
PA103exsA::Ω	Mutant of PA103 defective in expression of type III secretion genes	11
PA103pscJ::Tn5	Mutant of PA103 defective in production of PscJ, a putative component of the bacterial type III secretion apparatus	15, 20
PA103pcrG::Tn5	Mutant of PA103 defective in secretion of PopB and PopD, putative components of the type III translocation complex	15, 20
PA103exoU::Tn5	Mutant of PA103 defective iin production of ExoU	14, 20
PA103exoU::Tn5 (pAH807)	PA103exoU::Tn5 harboring a plasmid containing an intact copy of the exoU gene and its chaperone, SpcU	6, 14, 20
PA103tox::Ω	Mutant of PA103 defective in production of exotoxin A	21
PAK	P. aeruginosa laboratory strain	37
6294	P. aeruginosa hyperinvasive corneal isolate	9
PAO1	P. aeruginosa laboratory strain	17
388	P. aeruginosa laboratory strain	2, 18
617000	P. aeruginosa respiratory isolate	14
M90T	Wild-type S. flexneri serotype 5	41; a generous gift from Arturo Zychlinsky
BS176	Plasmid-cured derivative of M90T	41; a generous gift from Arturo Zychlinsky

^aTn5 refers to a Tn5 transposon modifed to contain the gentamicin resistance gene (20).