BACKGROUND: Stenotrophomonas maltophilia (S. maltophilia) is a Gram-negative pathogen that causes opportunistic infections. Although the mortality rate among patients with nosocomial infections caused by S. maltophilia is high, the risk factors for infection vary among studies. Moreover, S. maltophilia is highly resistant to several classes of antimicrobial agents. To date, few studies on S. maltophilia have been conducted in Japan, and the details remain unclear. Therefore, the objective of this study was to investigate the risk factors associated with S. maltophilia infection and the antimicrobial susceptibility of S. maltophilia isolates identified in our hospital.
METHODS: In this study, we investigated the risk factors associated with S. maltophilia infection and clinical characteristics isolated from patients at the NTT Medical Center Tokyo (Tokyo, Japan). We retrospectively examined the S. maltophilia isolates and the corresponding patients between March 2022 and August 2023.
RESULTS: Fifty-eight patients with S. maltophilia isolated (median age, 80.5 years; age range, 49-100 years; 70.7% male) were enrolled in this study. Twelve cases (20.7%) were placed in the S. maltophilia infection group and 46 cases were placed in the S. maltophilia colonization group. Central venous (CV) catheterization and higher Sequential Organ Failure Assessment (SOFA) scores were identified as risk factors for S. maltophilia infection. In addition, the 30-day mortality rate was significantly higher, and the survival rate was significantly lower in patients with S. maltophilia infection. The antimicrobial susceptibility rates of S. maltophilia were as follows: 28.6% for ceftazidime, 2.4% for cefozopran, 96.6% for levofloxacin, 100% for minocycline, and 98.3% for trimethoprim-sulfamethoxazole.
CONCLUSIONS: In actual clinical practice, S. maltophilia was more frequently isolated from sputum. However, most of the cases were colonization, and cases of infection were rare. Early treatment initiation should be considered for S. maltophilia infection in cases where the pathogen is detected from sterile sites, such as blood cultures and pleural fluid or from sputum in cases with a high SOFA score and CV catheter insertion.
