Staphylococcus aureus is an important cause of various
infections in humans, including
bacteremia, skin and
soft tissue infections, and
infections associated with implanted medical devices. The emergence of hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) underscores the urgent and unmet need to develop novel, safe, and effective
antibiotics against these multidrug-resistant clinical isolates.
Oxazolidinone antibiotics such as
linezolid have excellent oral bioavailability and provide coverage against MRSA
infections. However, their widespread and long-term use is often limited by adverse effects, especially myelosuppression. TBI-223 is a novel
oxazolidinone with potentially reduced myelosuppression, compared to
linezolid, but its efficacy against MRSA
infections is unknown. Therefore, the preclinical efficacy of TBI-223 (80 and 160 mg/kg twice daily) was compared with that of
linezolid (40 and 80 mg/kg twice daily) and
sham treatment in mouse models of MRSA
bacteremia, skin
wound infection, and orthopedic-implant-associated
infection. The dosage was selected based on mouse pharmacokinetic analysis of both
linezolid and TBI-223, as well as measurement of the MICs. In all three models, TBI-223 and
linezolid had comparable dose-dependent efficacies in reducing bacterial burden and disease severity, compared with
sham-treated control mice. Taken together, these findings indicate that TBI-223 represents a novel
oxazolidinone antibiotic that may provide an additional option against MRSA
infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans. IMPORTANCE Staphylococcus aureus is the predominant cause of bloodstream, skin, and bone
infections in humans. Resistance to commonly used
antibiotics is a growing concern, making it more difficult to treat
staphylococcal infections. Use of the
oxazolidinone antibiotic linezolid against resistant strains is hindered by high rates of adverse reactions during prolonged
therapy. Here, a new
oxazolidinone named TBI-223 was tested against S. aureus in three mouse models of
infection, i.e.,
bloodstream infection, skin
infection, and bone
infection. We found that TBI-223 was as effective as
linezolid in these three models. Previous data suggest that TBI-223 has a better safety profile than
linezolid. Taken together, these findings indicate that this new agent may provide an additional option against MRSA
infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans.