Impact of multidrug-resistant Pseudomonas aeruginosa bloodstream infections on mortality in oncology patients.

INTRODUCTION

Pseudomonas aeruginosa (PAE) is among the most frequent causes of bloodstream infections (BSIs) in cancer patients. Resistant strains are associated with increased morbidity and mortality.

METHODOLOGY: A retrospective study was conducted at a tertiary oncology hospital in Mexico City, including all episodes of PAE-BSI. The isolates were classified as susceptible, carbapenem-resistant (CR), multidrug-resistant (MDR), or difficult-to-treat resistant (DTR).

RESULTS

A total of 259 PAE-BSI episodes were analyzed: 202 (78.4%) susceptible, 19 (7.3%) CR, 13 (5.0%) MDR, and 25 (9.7%) DTR. Resistant strains were significantly associated with prior antibiotic use (84.2% vs. 52.5%), more extended hospital stays (18 vs. 9 days), septic shock (36.8% vs. 19.8%), and inappropriate empiric therapy (54.4% vs. 19.3%). Overall, 30-day mortality was 38.2%, rising to 47.4% in CR, 84.6% in MDR, and 76% in DTR cases; compared with 29.7% in susceptible isolates (p < 0.001). No mortality benefit was observed with combination therapy compared to monotherapy. Multivariate analysis indicated that age ≥ 60 years, advanced oncological status, secondary bacteremia, septic shock, invasive mechanical ventilation, inadequate source control, and carbapenem strains were independent predictors of 30-day mortality. Appropriate antimicrobial therapy was a protective factor.

CONCLUSIONS

Resistant PAE-BSI in cancer patients was associated with longer hospitalizations and a significantly increased mortality rate. Appropriate antimicrobial therapy can lead to a reduction in mortality.