Int J Antimicrob Agents. 2021 Oct 10:106450. doi: 10.1016/j.ijantimicag.2021.106450. Online ahead of print.
Few studies have assessed the clinical and bacterial characteristics of Pseudomonas aeruginosa (PA) bacteraemic pneumonia (BN) episodes. In the present study, all non-duplicated PA BN episodes from a tertiary hospital were included (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 BN 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. β-lactamases/carbapenemases were detected in 29 isolates: blaVIM-2 (27.2%) and blaGES type (25.5%) [blaGES-5 (20.0%), blaGES-1 (3.6%) and blaGES-20 (1.8%)]. The most prevalent O-serotype was 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). In addition, late mortality (67.3%) was influenced by septic shock (aOR 8.84, 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, blaGES, gyrA [T83I], parC [S87L], exoU and O11 serotype) showed significant differences in patients' outcomes. Our results confirm the high mortality associated with PA BN. Besides relevant clinical characteristics and inappropriate empirical therapy, bacteria-specific genetics factors, such as XDR phenotype, adversely affect the outcome of PA BN.