Stenotrophomonas maltophilia bloodstream infection in patients with hematologic malignancies: a retrospective study and in vitro activities of antimicrobial combinations

Abstract

BackgroundStenotrophomonas maltophilia causes serious infections in immunocompromised hosts. Here, we analyzed the clinical characteristics of S. maltophilia bloodstream infection (BSI) in patients with hematologic malignancies and evaluated in vitro synergistic effects of antimicrobial combinations.MethodsWe retrospectively reviewed all consecutive episodes of S. maltophilia BSIs in adult hematologic patients from June 2009 to May 2014, with in vitro susceptibility and synergy tests using high-throughput bioluminescence assay performed for available clinical isolates.ResultsAmong 11,004 admissions during 5-year period, 31 cases were identified as S. maltophilia BSIs. The incidence rate of S. maltophilia BSI was 0.134 cases/1,000 patient-days. Overall and attributable mortality of S. maltophilia BSI was 64.5% and 38.7%, respectively. Severe neutropenia (adjusted hazard ratio [HR] 5.24, p =0.013), shock at the onset of BSI (adjusted HR 6.05, p <0.001), and pneumonia (adjusted HR 3.15, p =0.017) were independent risk factors for mortality. In vitro susceptibilities to ceftazidime, levofloxacin, ticarcillin-clavulanic acid (TIM) and trimethoprim-sulfamethoxazole (SXT) were 11.1%, 44.0%, 40.7%, and 88.9%, respectively. MIC50/MIC90 for moxifloxacin and tigecycline were 1/4 mg/L and 4/8 mg/L. The 50% and 90% fractional inhibitory concentrations (FIC50/FIC90) of clinical isolates against a combination of SXT and TIM were 0.500/0.750. For SXT plus levofloxacin or moxifloxacin, FIC50/FIC90 were 0.625/1.000 and 0.625/0.625, respectively.ConclusionS. maltophilia BSIs show high mortality, which is related to severe neutropenia, shock, and S. maltophilia pneumonia. Based upon drug susceptibility testing, the primary treatment of choice for S. maltophilia BSIs should be SXT in hematologic patients, rather than quinolones, with combination therapies including SXT serving as a feasible treatment option.

The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies

“…Other notable risk factors include the presence of an indwelling catheter, broad-spectrum antibiotic exposure, and prolonged hospitalization, all common occurrences in patients with hematologic malignancies [15,87,88]. Two observational studies of patients with hematologic malignancies who developed S. maltophilia bacteremia demonstrated attributable mortality rates of 24% and 38%, respectively, rates comparable to those of P. aeruginosa bacteremia [89,90]. Severe neutropenia, pneumonia, and severe sepsis were all independent risk factors for mortality.…”

“…Trimethoprim/sulfamethoxazole (TMP/SMX) is the preferred therapy for S. maltophilia infections and approximately 90% of isolates are susceptible [81,90,91]. Fluoroquinolones, most commonly levofloxacin, are considered alternatives to TMP/SMX therapy.…”

Vitamin K 3 Induces the Expression of the Stenotrophomonas maltophilia SmeVWX Multidrug Efflux Pump

“…maltophilia mainly causes nosocomial infections (48), although communityacquired infections can also occur (49). The population at risk is mostly composed of immunocompromised hosts, including intensive care unit (ICU) patients, patients with dialysis catheters, hematological diseases, and cystic fibrosis, and those treated with a wide spectrum of antibiotics (50)(51)(52)(53). Although our results indicate that vitK3 might induce the expression of the smeVWX efflux pump even at low concentrations and antagonizes the effects of ofloxacin and chloramphenicol against S. maltophilia, both in the presence and in the absence of this efflux pump, the clinical significance of these findings remains to be clearly established.…”

Twitching motility of Stenotrophomonas maltophilia under iron limitation: In-silico, phenotypic and proteomic approaches

“…In our study, five clinical isolates from blood exhibited larger zone of twitching under iron-depleted compared to normal conditions (20.00 mm for CS17, 25.00 mm for SM24, 33.00 mm for SM27, 36.00 mm for SM40, 35.00 mm for SM41) (see Table 1), but not statistically significant (p = 0.136). In such circumstances, high disease severity and mortality were associated with hospital-acquired S. maltophilia bacteremia in comparison with community [46][47][48][49][50].…”