What is the X in X-mas?
cephalosporin ceph·a·lo·spo·rin (sěf-ə-lə-spôr'ĭn)
Any of various broad-spectrum antibiotics, closely related to the penicillins, that were originally derived from the fungus Cephalosporium acremonium.
any of a group of beta-lactam antibiotics that inhibit the synthesis of a structural component of the bacterial cell wall. The cephalosporins were first isolated from cultures of the fungus Cephalosporium acremonium. Modifications of the beta-lactam ring have resulted in more than 20 derivatives with a range of antibacterial properties. The cephalosporins are often used as an alternative in patients who are sensitive to penicillin.