Clinical predictors of Stenotrophomonas maltophilia bacteremia in adult patients with hematologic malignancy

Stenotrophomonas maltophilia (SM) has emerged as an important nosocomial pathogen with high morbidity and mortality. Because of its unique antimicrobial susceptibility pattern, appropriate antimicrobial therapy for SM bacteremia is still challenging, especially in immunocompromised patients. The present study was performed to assess clinical predictors of SM bacteremia in adult patients with hematologic malignancy. From 2006 through 2016, a case-control study was performed at a tertiary-care hospital. Case patients were defined as SM bacteremia in patients with hematologic malignancy. Date- and location-matched controls were selected from among patients with gram-negative bacteremia (GNB) other than SM. A total of 118 cases of SM bacteremia were identified and compared to 118 controls. While pneumonia was the most common source of SM bacteremia, centralline-associated infection was most common in the controls. The overall 30-day mortality rate of cases with SM bacteremia was significantly higher than that of the controls (61.0 and 32.2%, respectively; P < 0.001). A multivariable analysis showed that polymicrobial infection, previous SM isolation, the number of antibiotics previously used ≥ 3, and breakthrough bacteremia during carbapenem therapy were significantly associated with SM bacteremia (all P < 0.01). Previous use of trimethoprim/sulfamethoxazole (TMP/SMX) was negatively association with SM bacteremia (P = 0.002). Our data suggest that SM is becoming a significant pathogen in patients with hematologic malignancy. Several clinical predictors of SM bacteremia can be used for appropriate antimicrobial therapy in hematologic patients with suspected GNB.