Genotypic and phenotypic analysis of type III secretion system in a cohort of Pseudomonas aeruginosa bacteremia isolates: evidence for a possible association between O serotypes and exo genes.
The type III secretion system (TTSS) of Pseudomonas aeruginosa was characterized genetically and phenotypically in 92 epidemiologically unrelated bacteremic strains. Four groups of strains (TTSS types) were defined according to the level of type III protein secretion and kinetics of cytotoxicity. Type 1 strains (n=26) were highly and rapidly cytotoxic and secreted ExoU, type 2 strains (n=48) exhibited slower cytotoxic rates and expressed ExoS but not ExoU, type 3 strains (n=14) were poorly cytotoxic, and type 4 strains (n=4) were not cytotoxic. Type 3 and 4 strains did not have detectable secretion phenotype; however, some type 4 strains were able to reach a level of cytotoxicity similar to that of type 1 and type 2 strains when complemented in trans by a functional exsA gene. A statistically significant association (P<.001) was found between TTSS types and detection of the mutually exclusive exoU and exoS genes. In addition, 24 of 25 serotype O:1, O:10, and O:11 strains contained exoU, whereas 54 of 55 serotype O:3, O:4, O:6, O:12, and O:16 strains contained exoS (P<.001). Our results demonstrate correlations among exoU or exoS genotype, TTSS phenotype, and O serotype in bacteremic P. aeruginosa isolates.
Berthelot
Philippe
P
Microbiology Laboratory, Groupe Immunité des Muqueuses et Agents Pathogènes, University Hospital of Saint-Etienne, Saint-Etienne, France.
Attree
Ina
I
Plésiat
Patrick
P
Chabert
Jacqueline
J
de Bentzmann
Sophie
S
Pozzetto
Bruno
B
Grattard
Florence
F
D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016470:Bacteremia / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D005798:Genes, Bacterial / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D010641:Phenotype; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D012703:Serotyping
D001426:Bacterial Proteins; D001427:Bacterial Toxins; C111749:pseudomonas exoprotein A protein, Pseudomonas aeruginosa; D036002:ADP Ribose Transferases; C444820:exoenzyme S