High mortality by nosocomial infections caused by carbapenem-resistant P. aeruginosa in a referral hospital in Brazil: facing the perfect storm

Abstract

Introduction. Carbapenem-resistant Pseudomonas aeruginosa is responsible for increased patient mortality.Gap Statement. Five and 30 day in-hospital all-cause mortality in patients with P. aeruginosa infections were assessed, followed by evaluations concerning potential correlations between the type III secretion system (TTSS) genotype and the production of metallo-β-lactamase (MBL).Methodology. This assessment comprised a retrospective cohort study including consecutive patients with carbapenem-resistant infections hospitalized in Brazil from January 2009 to June 2019. PCR analyses were performed to determine the presence of TTSS-encoding genes and MBL genes.Results. The 30-day and 5-day mortality rates for 262 patients were 36.6 and 17.9 %, respectively. The unadjusted survival probabilities for up to 5 days were 70.55 % for patients presenting exoU-positive isolates and 86 % for those presenting exo-negative isolates. The use of urinary catheters, as well as the presence of comorbidity conditions, secondary bacteremia related to the respiratory tract, were independently associated with death at 5 and 30 days. The exoS gene was detected in 64.8 % of the isolates, the presence of the exoT and exoY genes varied and exoU genes occurred in 19.3 % of the isolates. The exoU genotype was significantly more frequent among multiresistant strains. MBL genes were not detected in 92 % of the isolates.Conclusions. Inappropriate therapy is a crucial factor regarding the worse prognosis among patients with infections caused by multiresistant P. aeruginosa, especially those who died within 5 days of diagnosis, regardless of the genotype associated with TTSS virulence.

Keywords: Pseudomonas aeruginosa; Type III secretion system; carbapenem-resistant Enterobacteriaceae; multi-drug resistance; virulence.