Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen that currently poses a serious threat to global health. Novel antimicrobial agents against MRSA are urgently being developed. In this study, we investigated WYBQ-4, which is an effective antibacterial agent with potent bactericidal activity and bactericidal efficiency against MRSA USA300 and clinical isolate strains. In addition, WYBQ-4 exhibited low cytotoxicity without hemolytic activity according to a safety evaluation. Importantly, WYBQ-4 showed potent in vivo efficacy in an MRSA-induced mouse pneumonia model, systemic infection model, and intramuscular infection model. The efficacy of this new cephalosporin against MRSA was associated with a high affinity for penicillin-binding proteins (PBP1, PBP2, PBP3, PBP4, PBP2a) evaluated in a competition assay using bocillin as a reporter. In conclusion, WYBQ-4 has a significant bactericidal effect in vitro and in vivo, indicating that it is a promising compound to control MRSA infection. IMPORTANCE Antibiotic resistance is spreading faster than the introduction of new compounds into clinical practice, causing a public health crisis. Novel antimicrobial agents against MRSA are urgently being developed. In this study, we investigated WYBQ-4, which is an effective antibacterial agent with potent bacteriostatic activity and bactericidal efficiency against MRSA USA300 and clinical isolate strains. WYBQ-4 showed potent in vivo efficacy in MRSA-induced mouse models. Subsequently, we further revealed its antibacterial mechanism. In conclusion, WYBQ-4 has a significant bactericidal effect in vitro and in vivo, indicating that it is a promising compound to control MRSA infection.
Keywords: PBP2a; WYBQ-4; bactericidal agent; methicillin-resistant Staphylococcus aureus.