• Carmen Peña, Gabriel Cabot, Silvia Gómez-Zorrilla, Laura Zamorano, Alain Ocampo-Sosa, Javier Murillas, Benito Almirante, Virginia Pomar, Manuela Aguilar, Ana Granados, Esther Calbo, Jesús Rodríguez-Baño, Fernando Rodríguez-López, Fe Tubau, Luis Martínez-Martínez, Antonio Oliver, and Spanish Network for Research in Infectious Diseases (REIPI).
• Servicio de Enfermedades Infecciosas, Hospital Universitario de Bellvitge-IDIBELL, Barcelona.
• Clin. Infect. Dis. 2015 Feb 15;60(4):539-48.

BackgroundThe type III secretion system (TTSS) is a major virulence determinant of Pseudomonas aeruginosa. The objective of this study was to determine whether the TTSS genotype is a useful prognostic marker of P. aeruginosa bacteremia mortality. We also studied the potential association between TTSS genotypes and multidrug-resistant (MDR) profiles, and how this interaction impacts the outcome of bloodstream infections.MethodsWe performed a post hoc analysis of a published prospective multicenter cohort of P. aeruginosa bloodstream infections. The impact in mortality of TTSS genotypes (exoS, exoT, exoU, and exoY genes) and resistance profiles was investigated. Cox regression analysis was used to control for confounding variables.ResultsAmong 590 patients, the 30-day mortality rate was 30% (175 patients), and 53% of them died in the first 5 days (early mortality). The unadjusted probabilities of survival until 5 days was 31.4% (95% confidence interval [CI], 17.4%-49.4%) for the patients with exoU-positive isolates and 53.2% (95% CI, 44.6%-61.5%) for exoU-negative isolates (log rank P = .005). After adjustment for confounders, exoU genotype (adjusted hazard ratio [aHR], 1.90 [95% CI, 1.15-3.14]; P = .01) showed association with early mortality. In contrast, late (30-day) mortality was not influenced by TTSS genotype but was independently associated with MDR profiles (aHR,1.40 [95% CI, 1.01-1.94]; P = .04). Moreover, the exoU genotype (21% of all isolates) was significantly less frequent (13%) among MDR strains (particularly among extensively drug-resistant isolates, 5%), but was positively linked to moderately resistant (1-2 antipseudomonals) phenotypes (34%).ConclusionsOur results indicate that the exoU genotype, which is associated with specific susceptibility profiles, is a relevant independent marker of early mortality in P. aeruginosa bacteremia.© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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