Discordant Susceptibilities of Enterobacterales to Different Tetracycline Classes.

When bacteria are tetracycline- or doxycycline-resistant, the ability of these bacteria to be susceptible to the other tetracyclines is not well defined. Consequently, gaining knowledge about the ability to infer Enterobacterales susceptibility to minocycline and third-generation tetracycline antibiotics from surrogates is vital. In this study, we show that tigecycline may be a reasonable surrogate from which clinicians can infer omadacycline and eravacycline susceptibilities, even in the presence of doxycycline and tetracycline resistance. Yet, minocycline susceptibility cannot be inferred from third-generation tetracyclines used as surrogates when Enterobacterales is resistant to doxycycline and tetracycline.