Risk Factors Associated with Stenotrophomonas maltophilia Bacteremia: A Matched Case-Control Study

Abstract

Stenotrophomonas maltophilia is an important nosocomial bacterial pathogen, as is Pseudomonas aeruginosa. Differentiation of these bacteria as bacteremic agents is critical in the clinical setting and to define a therapeutic strategy; however, the associated factors and prognosis for S. maltophilia bacteremia have not been fully evaluated to adequately characterize these factors. We first conducted a matched case-control study to clarify these questions. A total of 30 case patients with S. maltophilia bacteremia were compared with 30 control patients with P. aeruginosa bacteremia between January 2005 and August 2014, according to matching criteria based on underlying disease, age, and gender. The 30-day mortality rate for the case patients (53.3%) was significantly higher than that of the control group (30.0%) (P = 0.047, using the log-rank test). Conditional logistic regression analysis showed that the predisposing factors specific for the detection of S. maltophilia bacteremia were indwelling artificial products other than a central venous catheter, ICU stay, and previous use of anti-MRSA drugs. The high severity of illness was associated with mortality in both case and control patients. Interestingly, inappropriate antimicrobial treatment was an additional independent risk factor for mortality in only the case patients with S. maltophilia bacteremia (odds ratio = 13.64, P = 0.048). Monotherapy with fluoroquinolones inactive against the S. maltophilia isolates was mainly responsible for the inappropriate treatment. These results suggest that more precise prediction and more appropriate treatment might improve the prognosis of patients with S. maltophilia bacteremia.

Clinical Characteristics of <i>Stenotrophomonas maltophilia</i> Bacteremia: A Regional Report and a Review of a Japanese Case Series

“…In our hospitals, more than half of the patients were admitted to an ICU (52.3%) or intubated (54.5%). The ICU admission rate was higher in our study than in previous reports (35.2% and 36.7%) (9,10). The mean number of hospitalization days before the occurrence of SMB were longer in our study than in a previous study; 59.7 days (6 to 145 days) in our hospitals and 50 days (28 to 100 days) in the previous study (9).…”

“…A summary of all 44 cases is shown in Table 1, along with previously reported Japanese cases (8-10). …”

“…A similar phenomenon was seen in a recent report on candidemia (26). SMB is reported to yield a worse outcome than other non-fermenting Gram-negative bacteria such as P. aeruginosa (10). However, our results suggested that SMB itself may not lead to fatal outcomes but can be a prognostic factor for critically ill patients.…”

“…To our knowledge, there have been three case series reported from Japanese medical facilities: 53 cases by Araoka et al in 2010 (8), 54 cases by Hotta et al in 2013 (9), and 30 cases by Sumida et al in 2015 (10). We conducted an additional investigation of SMB in two other hospitals in Japan and summarized the data combined with these previous reports to reveal the clinical characteristics of SMB in Japanese clinical settings.…”

<p><em>Stenotrophomonas maltophilia</em> Infections: Clinical Characteristics and Factors Associated with Mortality of Hospitalized Patients</p>

“…15,17 Some previous studies found fluoroquinolone-resistant strain and inappropriate fluoroquinolone treatment when the organisms resistant to were factors predicting the non-survival outcome. 28,29 Although minocycline has demonstrated very promising in vitro activity against the isolates, this agent is unfortunately not presently available in Thailand.…”