New Insights into the Antimicrobial Susceptibility of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an opportunistic gram-negative bacillus with intrinsic resistance to a variety of antibiotics. Since clinical trial data are lacking, the optimal antimicrobial regimen is unknown. These factors make S. maltophilia increasingly challenging for the treating clinician. A recent study by Sader and colleagues analyzed the antimicrobial susceptibility of 1,400 S. maltophilia isolates collected from U.S. medical centers between 2019 and 2023. Aztreonam-avibactam, which inhibited 99.6% of isolates at ≤ 8 mcg/mL, was found to have the highest levels of in vitro activity. Trimethoprim-sulfamethoxazole, which has historically been a preferred agent, had slightly lower activity (96.9% susceptible), followed by minocycline (89.2%) and levofloxacin (78.9%). The results from this in vitro study suggest that aztreonam-avibactam may be a highly effective option for treating S. maltophilia infections, especially in multidrug-resistant cases.