Antimicrobial susceptibility of clinical isolates of Stenotrophomonas maltophilia from Europe, Asia, and Latin America (2018-2023).

Background: The occurrence of Stenotrophomonas maltophilia infections, especially pneumonia, has increased consistently in the last years. We evaluated the antimicrobial susceptibility of a large collection of S. maltophilia collected in Europe, Asia, and Latin America.

Methods: Total 1287 clinical isolates were collected from 71 medical centres located in Western Europe (W-EU; n = 682; 28 centres in 10 countries), Eastern Europe and Mediterranean region (E-EU; n = 320; 18 centres in 11 countries), the Asia-Pacific region (APAC; n = 182; 15 centres in 7 countries), and Latin America (LATAM; n = 103; 10 centres in 7 countries). Most isolates were from patients with pneumonia (n = 790) and bloodstream infection (n = 234). Isolates were susceptibility tested by the CLSI broth microdilution method.

Results: Aztreonam-avibactam was the most active compound against isolates from all regions and infection types (MIC50/90, 4/4 mg/l; 99.5% inhibited at ≤8 mg/l). The percentage of isolates inhibited at ≤8 mg/l varied from 99.3% in W-EU to 100.0% in APAC and LATAM. Trimethoprim-sulfamethoxazole (MIC50/90, ≤0.12/0.5 mg/l; 95.6/96.3% susceptible per CLSI/EUCAST) and minocycline (MIC50/90, 0.5/1 mg/l; 92.7% susceptible per CLSI) also were active. Aztreonam-avibactam remained active against trimethoprim-sulfamethoxazole-resistant isolates, inhibiting 100.0% at ≤8 mg/l.

Conclusions: Aztreonam-avibactam may represent a valuable option to treat S. maltophilia infections, addressing a major unmet medical need.