Abstract
DL 473 is a 3-[(4-cyclopentyl-1-piperazinyl)iminomethyl] rifamycin SV derivative which inhibited staphylococci, streptococci (including Streptococcus faecalis, Listeria species, and Bacteroides species. DL 473 was less active than rifampin against these species. DL 473 did not inhibit Enterobacteriaceae nor most Pseudomonas species. A combination of DL 473 and vancomycin or nafcillin tested against staphylococci was primarily additive and antagonism was not encountered.