Predictors of mortality and progression from colonization to Stenotrophomonas maltophilia bloodstream infection in hematologic disorders: a single-center retrospective study.

BACKGROUND

Stenotrophomonas maltophilia (S. maltophilia) is an emerging multidrug-resistant pathogen that causes severe infections, particularly in immunocompromised patients. The bloodstream infection (BSI) of S. maltophilia is associated with high mortality rates, especially in patients with hematologic disorders. This study aimed to analyze the clinical characteristics and risk factors of S. maltophilia BSI in patients with hematologic disorders.

METHODS

We conducted a single-center retrospective study of 107 patients with hematologic disorders (stratified into colonization [n = 41], colonization-to-BSI [n = 37], and primary BSI [n = 29] cohorts) at Hematology Hospital, Chinese Academy of Medical Sciences between January 2021 and September 2024. Data on demographic characteristics, clinical features, laboratory results, treatment regimens, and outcomes were collected from electronic medical records. Blood cultures were performed using the BD BACTEC™ FX system, and bacterial identification was confirmed by MALDI-TOF MS. Antimicrobial susceptibility testing was conducted by the Vitek 2 Compact system. Statistical analyses, including Cox regression and logistic regression, were performed to identify risk factors for mortality.

RESULTS

The 30-day mortality rate was 34.8%. Independent risk factors for mortality included prolonged neutropenia (> 1 month) (HR = 1.57, p = 0.04), shock (HR = 2.44, p < 0.01), and ceftazidime resistance (HR = 1.95, p = 0.03). Polymicrobial infections were prevalent (84.8%), and inappropriate initial antibiotic therapy occurred in 42.4% of cases. Progression from colonization to BSI was associated with neutropenia (OR = 6.85, p < 0.001), immunosuppressor use (OR = 7.20, p < 0.001), elevated CRP (> 100 mg/L, OR = 4.11, p = 0.001), and inappropriate antibiotic therapy (OR = 2.98, p = 0.039). A predictive model integrating these factors demonstrated strong performance (AUC = 0.89, 95% CI: 0.82-0.96).

CONCLUSION

S. maltophilia BSI is associated with high mortality, driven by host immunosuppression, antibiotic resistance, and delayed targeted therapy. The progression from colonization to BSI is strongly influenced by neutropenia, immunosuppressor, inflammatory markers, and inappropriate antibiotic use. These findings underscore the need for early risk stratification, and susceptibility-guided therapy in high-risk settings.