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Clin Infect Dis. 2015 Feb 15;60(4):539-48. doi: 10.1093/cid/ciu866. Epub 2014 Nov 6.

Influence of virulence genotype and resistance profile in the mortality of Pseudomonas aeruginosa bloodstream infections.

Author information

1
Servicio de Enfermedades Infecciosas, Hospital Universitario de Bellvitge-IDIBELL, Barcelona.
2
Unidad de Investigación, Servicio de Microbiología y Servicio de Medicina Interna, Hospital Universitario de Son Espases, Instituto de Investigación Sanitaria de Palma, Palma de Mallorca.
3
Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander.
4
Servicio de Enfermedades Infecciosas, Hospital Universitario Vall d'Hebrón.
5
Unidad de Enfermedades Infecciosas, Hospital Santa Creu i Sant Pau, Barcelona.
6
Servicio de Enfermedades Infecciosas, Hospital Universitario Virgen del Rocío, Sevilla.
7
Sección de Enfermedades Infecciosas, Consorci Hospitalari Parc Taulí, Sabadell.
8
Sección de Enfermedades Infecciosas, Hospital Mutua de Terrasa.
9
Sección de Enfermedades Infecciosas, Hospital Universitario Virgen Macarena, Sevilla.
10
Servicio de Microbiología Infecciosas, Hospital Universitario Reina Sofía-IMIBIC, Córdoba.
11
Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain.

Abstract

BACKGROUND:

The 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.

METHODS:

We 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.

RESULTS:

Among 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%).

CONCLUSIONS:

Our 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.

KEYWORDS:

Pseudomonas aeruginosa; bloodstream infections; multidrug resistance; type III secretion system; virulence

PMID:
25378459
DOI:
10.1093/cid/ciu866
[Indexed for MEDLINE]

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