In vitro evaluation of BL-S640, a new oral cephalosporin antibiotic.

BL-S640, a new oral cephalosporin analogue, was evaluated in vitro against 102 gram-negative and 80 gram-positive bacteria. The antimicrobial spectrum was similar to that of previous cephalosporin analogues. Good antimicrobial activity against strains of Escherichia coli, Klebsiella, staphylococci, and streptococci was demonstrated. Relatively poor activity and/or resistance was noted among most strains of Proteus, Providencia, Pseudomonas, and Serratia. In comparative studies BL-S640 had better activity against strains of Hemophilus influenzae, Staphylococcus aureus, and Enterobacteriaceae than many cephalosporin analogues. Variation of susceptibility results was dependent upon the type of media and inoculum size. Cross-resistance between BL-S640 cephalexin, cephalothin, and cefazolin was demonstrated. Among strains of Klebsiella the more rapid selection of resistance ot other cephalosporins was in contrast to BL-S640. Experience in vitro with BL-S640 has documented its antimicrobial activity,and further studies of pharmacokinetics and therapeutic efficacy are indicated.