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TOC-39, a novel parenteral broad-spectrum cephalosporin with excellent activity against methicillin-resistant
1Anticancer and Antimicrobial Research Laboratory, Taiho Pharmaceutical Co. Ltd., Hiraishi, Japan.
Abstract:
TOC-39, a new parenteral cephalosporin, is a hydroxyimino-type cephem antibiotic with vinylthio-pyridyl moiety at the 3 position. TOC-39 was evaluated for antibacterial activity against various clinically isolated strains. TOC-39 had excellent activity, stronger than that of methicillin, oxacillin, the cephalosporins tested, imipenem, gentamicin, minocycline, tobramycin, ofloxacin, and ciprofloxacin against methicillin-resistant Staphylococcus aureus (MRSA) and had an MIC comparable to that of vancomycin (the MICs of TOC-39 and vancomycin for 90% of the strains tested were 3.13 and 1.56 micrograms/ml, respectively). Against Enterococcus faecalis strains, which are resistant to cephalosporins, TOC-39 was twice as active as ampicillin. Against methicillin-susceptible S. aureus, coagulase-negative Staphylococcus spp., and Streptococcus pneumoniae, TOC-39 was twice as active as or more active than cefotiam, ceftazidime, flomoxef, and cefpirome. Against Streptococcus pyogenes, TOC-39 was superior to cefotiam, ceftazidime, and flomoxef and was similar to cefpirome. In addition, the activity of TOC-39 was equal to or greater than that of cefotiam, ceftazidime, flomoxef, and cefpirome against Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Morganella morganii. In terms of bactericidal effect against MRSA, TOC-39 was superior to vancomycin. No mutant resistant to TOC-39 or vancomycin was obtained from susceptible MRSA strains. In murine systemic infection models, TOC-39 showed potent activity against S. aureus and E. coli. Against highly MRSA, the activity of TOC-39 was comparable to that of vancomycin.
Insights
TOC-39, a novel cephalosporin antibiotic, demonstrates potent antibacterial activity against challenging pathogens like methicillin-resistant Staphylococcus aureus (MRSA). This new agent shows promise, outperforming many existing antibiotics in vitro and in vivo.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global health threat due to its resistance to conventional antibiotics.
- The development of new antimicrobial agents with novel mechanisms of action is crucial for combating resistant bacterial infections.
Purpose of the Study:
- To evaluate the in vitro and in vivo antibacterial activity of TOC-39, a new parenteral cephalosporin.
- To compare the efficacy of TOC-39 against various clinically relevant bacterial strains, including MRSA, with established antibiotics.
Main Methods:
- In vitro susceptibility testing (Minimum Inhibitory Concentration - MIC) was performed against a panel of clinically isolated bacterial strains.
- Bactericidal activity against MRSA was assessed.
- Murine systemic infection models were utilized to evaluate in vivo efficacy.
- Resistance development potential was investigated.
Main Results:
- TOC-39 exhibited potent activity against MRSA, with MICs comparable to vancomycin and superior bactericidal effect.
- The antibiotic demonstrated strong activity against Enterococcus faecalis, methicillin-susceptible S. aureus, coagulase-negative Staphylococci, and Streptococcus pneumoniae.
- TOC-39 showed comparable or superior activity to several other cephalosporins and broad-spectrum antibiotics against Gram-negative bacteria like E. coli and H. influenzae.
- In vivo studies confirmed potent activity against S. aureus and E. coli infections in murine models.
Conclusions:
- TOC-39 is a promising new parenteral cephalosporin with broad-spectrum antibacterial activity, particularly effective against MRSA.
- Its efficacy in both in vitro and in vivo models suggests potential as a valuable therapeutic option for serious bacterial infections.