In vitro activity of a new cephalosporin ME-1206 compared with other agents

The in vitro activity of ME-1206, a new aminothiazolyl cephalosporin that can be orally absorbed when converted to an ester, was compared with that of other beta-lactams. ME-1206 inhibited 50% of the Enterobacteriaceae at 2 micrograms/ml, similar to cefotaxime, ceftazidime, and cefixime. It did not inhibit, MIC greater than or equal to 32 micrograms/ml, Enterobacter species or Citrobacter freundii resistant to cefotaxime and ceftazidime, and it was less active than cefotaxime and ceftazidime against Serratia marcescens. Haemophilus influenzae, Neisseria gonorrhoeae, and Moraxella catarrhalis were inhibited by less than or equal to 0.25 micrograms/ml of ME-1206 inhibited hemolytic streptococci groups A, B, C, and G, MIC90 0.06 micrograms/ml, but it did not inhibit enterococci. Pseudomonas aeruginosa and other pseudomonads were resistant to ME-1206. MICs and MBCs of ME-1206 for susceptible species were within a dilution. ME-1206 was not hydrolyzed by TEM-1 or TEM-2, but was hydrolyzed by TEM-3 and TEM-5. ME-1206 was hydrolyzed by beta-lactamases of Morganella, Proteus vulgaris, and K1 of Klebsiella oxytoca, but minimally by the P99 beta-lactamase of Enterobacter cloacae. ME-1206 is comparable in in vitro activity and beta-lactamase stability to many of the current cephalosporins.