In vitro and in vivo antibacterial activities of OPC-20011, a novel parenteral broad-spectrum 2-oxaisocephem antibiotic.
OPC-20011, a new parenteral 2-oxaisocephem antibiotic, has an oxygen atom at the 2- position of the cephalosporin frame. OPC-20011 had the best antibacterial activities against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae: MICs at which 90% of the isolates were inhibited were 6.25, 6.25, and 0.05 microg/ml, respectively. Its activity is due to a high affinity of the penicillin-binding protein 2' in MRSA, an affinity which was approximately 1,050 times as high as that for flomoxef. Against gram-negative bacteria, OPC-20011 also showed antibacterial activities similar to those of ceftazidime. The in vivo activities of OPC-20011 were comparable to or greater than those of reference compounds in murine models of systemic infection caused by gram-positive and -negative pathogens. OPC-20011 was up to 10 times as effective as vancomycin against MRSA infections in mice. This better in vivo efficacy is probably due to the bactericidal activity of OPC-20011, while vancomycin showed bacteriostatic activity against MRSA. OPC-20011 produced a significant decrease of viable counts in lung tissue at a dose of 2.5 mg/kg of body weight, an efficacy similar to that of ampicillin at a dose of 10 to 20 mg/kg on an experimental murine model of respiratory tract infection caused by non-ampicillin-susceptible S. pneumoniae T-0005. The better therapeutic efficacy of OPC-20011 was considered to be due to its potent antibacterial activity and low affinity for serum proteins of experimental animals (29% in mice and 6.4% in rats).
Matsumoto
M
M
Microbiological Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima City, Tokushima Prefecture 771-0192, Japan. m.matsumoto@research.otsuka.co.jp
Tamaoka
H
H
Ishikawa
H
H
Kikuchi
M
M
D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000188:drug therapy; D001426:Bacterial Proteins; D001798:Blood Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D006602:Hexosyltransferases; D007769:Lactams; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008826:Microbial Sensitivity Tests; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D051381:Rats; D017207:Rats, Sprague-Dawley
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001798:Blood Proteins; D002352:Carrier Proteins; D007769:Lactams; C115649:OPC 20011; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase