Purpose: To better guide clinical use, we determined the in vitro antimicrobial activity of the new drug eravacycline and other tetracycline derivatives against levofloxacin (LVFX)-non-susceptible and/or trimethoprim-sulfamethoxazole (TMP-SMZ)-resistant Stenotrophomonas maltophilia and evaluated their dosing regimens.
Methods: Seventy-seven unique strains of S. maltophilia were isolated from sputa samples and airway aspirate samples that were either LVFX-non-susceptible and/or TMP-SMZ-resistant. Monte Carlo simulations were performed for different dosing regimens according to the population pharmacokinetic parameters of antibiotics in patients with respiratory tract infections at the minimum inhibitory concentration (MIC).
Results: Eravacycline had excellent in vitro antibacterial activity against LVFX-non-susceptible and/or TMP-SMZ-resistant S. maltophilia . Monte Carlo simulations showed that for LVFX-non-susceptible strains, the cumulative fraction of response (CFR) of minocycline at the conventional recommended dose of 100 mg q12 h was 90.90%; for TMP-SMZ-resistant strains, the CFR of minocycline at a high dose of 200 mg q12 h was only 91.64%. For strains resistant to both LVFX and TMP-SMZ, the CFR of minocycline at a high dose of 200 mg q12 h was 89.81%. In contrast, the CFR of tigecycline was less than 40%, even at a dose of 100 mg q12 h.
Conclusion: For pneumonia, minocycline is better for S. maltophilia that is non-susceptible to LVFX; for TMP-SMZ-resistant strains and strains that are not susceptible to either LVFX or TMP-SMZ, the efficiency of eravacycline requires further evaluation. Eravacycline may be a better choice for extremely resistant S. maltophilia strains that are non-susceptible to LVFX, TMP-SMZ, and minocycline.
Keywords: eravacycline, tetracyclines, levofloxacin, trimethoprim, sulfamethoxazole drug combination, Stenotrophomonas maltophilia , Monte Carlo method