INVITRO ANTIBACTERIAL ACTIVITY OF A NEW ORAL CEPHALOSPORIN, CEFTIBUTEN - A MULTICENTER STUDY

Minimal inhibitory concentration (MIC) of ceftibuten (CBT) were evaluated by agar dilution for 1 416 bacterial strains isolated in 5 hospitals. For Enterobacteriaceae, MIC 50 and 90 % were respectively (mu-g/ml): (I) Naturally non betalactamase producing species: E. coli 0,12-0,5, Shigella 0,06-0,12 and Salmonella 0,03-0,12, P. mirabilis 0,16-0,03. (II) Chromosomal penicillinase producing species: K. pneumoniae 0,03-0,5 and K. oxytoca 0,03-0,06. (III) Chromosomal cephalosporine producing species: E. cloacae and C. freundii 1- > 128: S. marcescens 0,25-2; indole + Proteus 0,06-0,12. Activity of CBT was not modified on plasmid mediated penicillinase producing strains; however, CBT was inactive on cephalosporinase hyperproducing strains, and its activity was variably reduced on broad spectrum betalactamases producing strains. CBT was inactive on P. aeruginosa (MIC greater-than-or-equal-to 32) and on A. baumannii (8- > 128). Haemophilus and Gonococci, regardless on betalactamase production status, were very susceptible to CBT (MIC 50 and 90 %: 0,06-0,5 and 0,016-0,06); it is the same situation for Meningococci; B. catarrhalis was generally inhibited by 0,03 to 2 (strains susceptible to penicilline G) and 0,12 to 16 (strains resistant to penicillin G). CBT was inactive on Straphylococci. Enterococci and Streptococci B were generally resistant; Streptococci A, C, G were inhibited by low concentrations: 0,06 to 1 (MIC 50 and 90 %: 0,25-0,5), whereas MIC for other Streptococci 0,12 to 128 (MIC 50 and 90 %: 8-128) and for Pneumococci were 0,25 to 16 (4-8). These antibacterial properties particularly against Enterobacteriaceae placed CBT in excellent position among oral cephalosporins.