Efficacy of cefiderocol and levofloxacin against <i>Stenotrophomonas maltophilia</i> in a hemorrhagic pneumonia mouse model

Cefiderocol (CFDC) is a promising drug for treating infections caused by <i>Stenotrophomonas maltophilia</i>, a multidrug-resistant pathogen. However, no evidence of its efficacy against <i>S. maltophilia</i>-induced hemorrhagic pneumonia has been reported. We compared the effects of CFDC and levofloxacin (LVFX) on improving survival as well as reducing bacterial load and pathological effects in a mouse model of <i>S. maltophilia</i> hemorrhagic pneumonia. The dosage of LVFX and CFDC was determined using a previously described method to establish <i>S. maltophilia-</i>induced hemorrhagic pneumonia in mice. CFDC and LVFX were administered intraperitoneally 3 h after bacterial infection. Treatment was administered using the calculated dosages. CFDC significantly improved survival, showed a tendency to reduce bacterial load in the blood and lungs, and revealed that hemorrhage was suppressed in pathological analysis compared with the control group. These results support the current recommendation for CFDC as a treatment option for <i>S. maltophilia</i> infections. However, its efficacy in our model was lower than that of LVFX. This may be due to the superior pulmonary tissue penetration of LVFX. Treatment strategies that consider tissue penetration are necessary for severe <i>S. maltophilia</i> infections. However, the use of LVFX must consider the risk of resistance development, whereas CFDC may be advantageous for treating resistant pathogens.