New prognostic marker in bacterial infections

26 de July de 2019

Researchers from the Group of Epidemiology and Pathogenic and Molecular Mechanisms of Infectious Diseases and Clinical Microbiology of IDIVAL have participated in a study where the lethality of Pseudomonas aeruginosa was evaluated in bloodstream infections using an animal model.

P. aeruginosa bacteria is an important cause of serious hospital infections, especially in immunocompromised patients or with chronic respiratory infections such as cystic fibrosis or other underlying chronic diseases. In recent years, infections caused by strains of P. aeruginosa resistant to multiple drugs (MDR) or extremely resistant (XDR) have severely compromised the selection of appropriate antibiotic treatments, all this is joined by the fact that P. aeruginosa has powerful toxins that this bacterium uses as virulence factors that it injects into host cells, all of which is associated with significant morbidity and mortality. Even more worrying are recent reports that have provided evidence of the existence of MDR / XDR clones of P. aeruginosa disseminated by hospitals worldwide, called high-risk epidemic clones.

In this prospective Spanish multicenter study published in the journal Clinical Microbiology and Infection (DOI: 10.1016 / j.cmi.2019.06.034) in this month of July, about 600 isolates of P. aeruginosa from patients have been analyzed with bacteraemias caused by this important human pathogen. This is the first study where the impact of the degree of virulence on the outcome of P. aeruginosa infections has been studied, using a virulence score in the C. elegans infection model (CEVS), classifying the isolates into high (CEVS) 4-5), intermediate (CEVS 3) and low virulence (CEVS 1-2), to assess the predictive value of lethality of C. elegans as a prognostic marker in P. aeruginosa bloodstream infections.

In this study it was observed that strains that show a high virulence phenotype tend to be associated with community acquired infections, while low virulence phenotypes tend to be associated with a greater severity of the disease, with some underlying conditions and with the respiratory source of infections. However, analysis of this large multicenter cohort revealed that bacterial virulence itself was not one of the leading causes of P. aeruginosa mortality in bloodstream infections. In summary, the results of this study indicated that the P. aeruginosa virulence phenotype in the C. elegans model correlates with the virulence genotype and resistance profile, but is a marker of poor prognosis in bloodstream infections.

Reference: Sánchez-Diener I, Zamorano L, Peña C, Ocampo-Sosa A, Cabot G, Gómez-Zorrilla S, Admiral B, Aguilar M, Granados A, Calbo E, JR Bath, Rodríguez-López F, Tubau F, Martínez -Martinez L, Navas A, Oliver A. Weighting the impact of virulence on the outcome of Pseudomonas aeruginosa bloodstream infections. Clin Microbiol Infect. 2019 Jul 6. pii: S1198-743X (19) 30389-1. doi: 10.1016 / j.cmi.2019.06.034.