Synthesis and antibacterial activity of 6315-S, a new member of the oxacephem antibiotic.

The synthesis and in vitro activity of 7 beta-difluoromethylthioacetamido-7 alpha-methoxy-3-[[1-(hydroxyethyl)-1H- tetrazol-5-yl]thiomethyl]-1-oxa-3-cephem-4-carboxylic acid sodium salt, 6315-S, are described. 6315-S shows good antibacterial activity against Gram-positive and Gram-negative bacteria, being especially highly active against clinical isolates of Staphylococcus aureus resistant to either ampicillin or methicillin. The structure-activity relationship of related 1-oxa and 1-thia cephems is also presented.