A positive correlation existed between the exoU+ genotype and increased risk for early mortality in patients with P. aeruginosa bloodstream infections, according to recent findings published in Clinical Infectious Diseases.
In a post-hoc analysis of a prospective, multicenter cohort study, researchers evaluated data on 590 patients with P. aeruginosa bacteremia. Researchers conducted PCR analysis to identify certain type III secretion system (TTSS) genotypes known to be major contributors to the virulence of the infection, including exoS, exoT, exoU and exoY. Controlling for confounding variables, they examined the impact of these enzymes, as well as drug resistance, on patient mortality.
The researchers found that 30% of patients died within 30 days of P. aeruginosa onset, and 53% of those patients (n=93) died within 5 days of onset. In patients with exoU-positive isolates, the unadjusted probability of 5-day survival was 31.4% (95% CI, 17.4%-49.4%); for patients with exoU-negative isolates, the unadjusted probability of survival to 5 days was 53.2% (95% CI, 44.6%-61.5%). After adjusting for confounders, an association existed between the exoU+ genotype and early mortality (adjusted HR=1.9; 95% CI, 1.15-3.14). Conversely, 30-day mortality did not appear to be affected by TTSS genotype, but it was independently linked to multidrug-resistant (MDR) profiles (adjusted HR=1.4; 95% CI, 1.01-1.94). Additionally, there was a significantly lower prevalence of the exoU+ genotype among MDR strains (13%) and extremely drug-resistant strains (5%), but the exoU+ genotype was detected in 34% of moderately resistant strains.
According to the researchers, these findings may be a valuable prognostic marker for P. aeruginosa mortality.
“Using a large multicenter prospective cohort of [P. aeruginosa] bacteremia, we demonstrate for the first time that the exoU+ genotype is independently associated with increased risk of early mortality of [P. aeruginosa] bloodstream infection, while late mortality is associated with MDR profiles,” the researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.