title: Antimicrobial activity of SM-17466, a novel carbapenem antibiotic with potent activity against methicillin-resistant Staphylococcus aureus.
abstract: The in vitro and in vivo antibacterial activities of SM-17466, a new 1 beta-methyl carbapenem, were evaluated against a wide range of clinical bacterial isoaltes and compared with the activities of meropenem, imipenem, vancomycin, and arbekacin. SM-17466 had a broad spectrum of action against gram-positive bacteria, showing especially potent activity against methicillin-resistant staphylococci. The MICs of SM-17466, meropenem, imipenem, vancomycin, and arbekacin at which 90% of clinical isolates of methicillin-resistant Staphylococcus aureus were inhibited were 3.13, 50, 100, 1.56, and 3.13 micrograms/ml, respectively. This activity of SM-17466 was almost equivalent to those of the antibiotics used for the treatment of infections caused by this organism. SM-17466 also showed bactericidal activity against methicillin-resistant S. aureus. In contrast, SM-17466 was less active against gram-negative bacteria, especially against Pseudomonas aeruginosa, compared with the other carbapenems; however, of the carbapenems, SM-17466 exhibited the highest activity against Haemophilus influenzae and Bacteriodes fragilis. SM-17466, at a 50% inhibitory concentration of less than 1 microgram/ml, bound to penicillin-binding proteins 1 to 4 in methicillin-susceptible S. aureus and also had good binding to penicillin-binding protein 2' in a methicillin-resistant strain (50% inhibitory concentration, 5.9 micrograms/ml). This high affinity, which was 10 and 20 times greater than those for meropenem and imipenem, respectively, was reflected in the potent activity of SM-17466 against methicillin-resistant S. aureus. SM-17466 demonstrated excellent in vivo efficacy against methicillin-susceptible and -resistant S. aureus strains in a mouse peritoneal infection model: the efficacy of SM-17466 against methicillin-resistant strains was equal to or one-third that of vancomycin. This activity was comparable to the in vitro activity of SM-17466. The subcutaneous injection of SM-17466 in mice revealed that the half-life of SM-17466 in serum was about 18 min, intermediate between those of vancomycin and arbekacin and 1.5-fold that of imipenem-cilastatin. SM-17466 was resistant to hydrolysis by swine renal dehydropeptidase I, to an extent comparable to the resistance shown by meropenem.
authors.affiliation: Discovery Research Laboratories III, Sumitomo Pharmaceuticals Research Center, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sumita
authors.forename: H
authors.initials: H
authors.lastname: Nouda
authors.forename: K
authors.initials: K
authors.lastname: Kanazawa
authors.forename: M
authors.initials: M
authors.lastname: Fukasawa
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D015780:Carbapenems / Q000378:metabolism / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D004150:Dipeptidases / Q000494:pharmacology; D006602:Hexosyltransferases; D008297:Male; D016106:Methicillin Resistance; D051379:Mice; D008813:Mice, Inbred ICR; D008826:Microbial Sensitivity Tests; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D001426:Bacterial Proteins; D015780:Carbapenems; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; C094160:SM 17466; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D004150:Dipeptidases; C038937:dipeptidase; D002267:Muramoylpentapeptide Carboxypeptidase