In vitro activity and beta-lactamase stability of a new carbapenem, SM-7338

Antimicrob Agents Chemother. 1989 Jul;33(7):1009-18. doi: 10.1128/AAC.33.7.1009.


SM-7338, a new carbapenem, inhibited most members of the family Enterobacteriaceae at MICs of 0.015 to 0.25 microgram/ml, including Klebsiella oxytoca, Citrobacter freundii, Enterobacter cloacae, and Proteus vulgaris isolates resistant to cefotaxime, ceftazidime, piperacillin, and gentamicin. It was two- to eightfold more active than imipenem, but it inhibited Pseudomonas aeruginosa at 1 to 8 micrograms/ml, which was comparable to the activity of imipenem. Haemophilus, Neisseria, and Branhamella species were inhibited by less than or equal to 0.25 microgram/ml, which was superior to the activity of imipenem. SM-7338 inhibited Staphylococcus aureus and coagulase-negative staphylococci at 0.25 microgram/ml, but for methicillin-resistant isolates MICs were 4 to 16 micrograms/ml. Group A, B, and C streptococci and Streptococcus pneumoniae were inhibited by less than or equal to 0.03 microgram/ml. Bacteroides species, including clindamycin-resistant isolates, were inhibited by 0.25 microgram/ml. There was no major inoculum size effect, and the MBCs were within a dilution of the MICs. SM-7338 was more active than imipenem at an acid pH under anaerobic conditions. Plasmid beta-lactamases of TEM-1, TEM-2, TEM-3, TEM-5, SHV-1, SHV-2, PSE-1, PSE-2, PSE-3, OXA-2, OXA-3, OXA-4, OXA-5, and OXA-7; Staphylococcus aureus enzymes; and the chromosomal beta-lactamases P-99 and K-1; Morganella species; and Proteus vulgaris did not hydrolyze SM-7338. The repeated transfer of organisms increased the MICs of SM-7338, as it did the MICs of imipenem.

MeSH terms

  • Anti-Bacterial Agents / metabolism
  • Anti-Bacterial Agents / pharmacology*
  • Bacteria / drug effects*
  • Drug Resistance, Microbial
  • Drug Synergism
  • Enzyme Induction / drug effects
  • Hydrogen-Ion Concentration
  • Imipenem / pharmacology
  • Meropenem
  • Methicillin / pharmacology
  • Microbial Sensitivity Tests
  • Penicillin Resistance
  • Thienamycins / pharmacology*
  • beta-Lactamase Inhibitors
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / metabolism*


  • Anti-Bacterial Agents
  • Thienamycins
  • beta-Lactamase Inhibitors
  • Imipenem
  • beta-Lactamases
  • Meropenem
  • Methicillin