719. Stenotrophomonas maltophilia in Japanese hospitals: Clinical characteristics and molecular epidemiology of infection and colonization cases registered in multicenter surveillance network

BACKGROUND: Stenotrophomonas maltophilia has become one of the major gram-negative pathogens causing nosocomial infections. However, comprehensive analysis of the clinical characteristics and molecular epidemiology of patients with S. maltophilia remains limited. METHODS: All patients with a clinical culture growing S. maltophilia were collected from April 2019 to March 2022 through the Multi-Drug Resistant organisms clinical research network (MDRnet), consisting of 12 tertiary care hospitals in Japan. The clinical characteristics, outcomes, antimicrobial susceptibility and molecular epidemiology of cases with S. maltophilia colonization and infection were investigated and compared. RESULTS: In total, 78 cases, 44 with colonization and 34 with infection, were included. The median age was 72.5 years (IQR: 61–78), and males accounted for 53 cases (67.9%). The most common comorbidity was localized solid malignancy (38.5%). Almost half of the patients (43.6%) were immunosuppressed, and the most common reason was antineoplastic chemotherapy (30.8%). Respiratory tract was the most common site of colonization (86.4%), whereas bacteremia accounted for more than half of infection cases (55.9%). The overall 30-day all-cause mortality rate was 20.5%, which was significantly higher in infection cases than in colonization cases (35.3% vs 9.1%; odds ratio, 5.33; 95% confidence interval, 1.40–25.45). Susceptibility rates to ceftazidime, levofloxacin, minocycline, and sulfamethoxazole-trimethoprim were 14.1%, 65.2%, 87.2%, and 100%, respectively. Multilocus sequence typing of the 78 strains revealed that they belonged to 62 different sequence types (STs), of which 42 were known STs and 36 were novel STs. Kaplan-Meier survival analysis [Figure: see text] CONCLUSION: S. maltophilia frequently colonizes the respiratory tract, and the mortality is significantly higher in infection cases. Sulfamethoxazole-trimethoprim remains active, but susceptibility to levofloxacin appear to be declining. The strains were genetically highly diverse, consistent with the likely environmental origin. DISCLOSURES: Masahiro Suzuki, PhD, KANTO Chemical co., inc.: Grant/Research Support Sho Saito, MD, PhD, Shionogi & Company, Limited: Grant/Research Support Yasufumi Matsumara, MD, PhD, Beckman Coulter: Grant/Research Support|Presicion System Science: Grant/Research Support|Toyobo: Grant/Research Support David van Duin, MD, PhD, Entasis: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Honoraria|Qpex: Advisor/Consultant|Roche: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Union: Advisor/Consultant|Utility: Advisor/Consultant Yohei Doi, MD, PhD, bioMerieux: Advisor/Consultant|FujiFilm: Advisor/Consultant|Gilead: Advisor/Consultant|Gilead: Honoraria|GSK: Advisor/Consultant|Meiji Seika Pharma: Advisor/Consultant|Moderna: Advisor/Consultant|Moderna: Honoraria|MSD: Advisor/Consultant|MSD: Honoraria|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Shionogi: Honoraria