Clinical and bacterial characteristics of Pseudomonas aeruginosa affecting the outcome of patients with bacteraemic pneumonia

Few studies have assessed the clinical and bacterial characteristics of Pseudomonas aeruginosa (PA) bacteraemic pneumonia (BP) episodes. This study analysed all non-duplicate PA-BP episodes from a tertiary hospital in 2013-2017. Epidemiology, clinical data, antimicrobial therapy and outcomes were recorded. Whole-genome sequencing was performed on PA blood isolates. The impact on early and late overall mortality of host, antimicrobial treatment and pathogen factors was assessed by multivariate logistic regression analysis. Of 55 PA-BP episodes, 32 (58.2%) were caused by extensively drug-resistant (XDR) PA. ST175 (32.7%) and ST235 (25.5%) were the most frequent high-risk clones. beta-Lactamases/carbapenemases were detected in 29 isolates, including bla(VIM-2) (27.2%) and bla(GES) type (25.5%) [bla(GES-5) (20.0%), bla(GES-1) (3.6%) and bla(GES-20) (1.8%)]. The most prevalent O-antigen serotypes were O4 (34.5%) and O11 (30.9%). Overall, an extensive virulome was identified in all isolates. Early mortality (56.4%) was independently associated with severe neutropenia (aOR = 4.64, 95% CI 1.11-19.33; P = 0.035) and inappropriate empirical antimicrobial therapy (aOR = 5.71, 95% CI 1.41-22.98; P = 0.014). Additionally, late mortality (67.3%) was influenced by septic shock (aOR = 8.85, 95% CI 2.00-39.16; P = 0.004) and XDR phenotype (aOR = 5.46, 95% CI 1.25-23.85; P = 0.024). Moreover, specific genetic backgrounds [ST235, bla(GES), gyrA (T83I), parC (S87L), exoU and O11 serotype] showed significant differences in patient outcomes. Our results confirm the high mortality associated with PA-BP. Besides relevant clinical characteristics and inappropriate empirical therapy, bacteria-specific genetics factors, such as XDR phenotype, adversely affect the outcome of PA-BP. (C) 2021 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.

Automated summary

This study analyzed the clinical and bacterial characteristics of Pseudomonas aeruginosa bacteraemic pneumonia episodes from a tertiary hospital between 2013-2017. The findings highlighted the impact of factors such as severe neutropenia, inappropriate empirical antimicrobial therapy, septic shock, and extensively drug-resistant phenotype on early and late mortality rates in these cases. Specific genetic backgrounds also played a significant role in patient outcomes.