CEFACLOR IS BACTERICIDAL AND HAS ANTIMICROBIAL ACTION AGAINST GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA SUCH AS COCCI, SPIROCHAETES, AND ACTINOMYCETES. CEFACLOR EXERTS ITS KILLING ACTION ON GROWING AND DIVIDING BACTERIA BY INHIBITING BACTERIAL CELL-WALL SYNTHESIS. ALTHOUGH THE MECHANISMS INVOLVED ARE STILL NOT PRECISELY UNDERSTOOD. BACTERIAL CELL WALLS ARE HELD RIGID AND PROTECTED AGAINST OSMOTIC RUPTURE BY PEPTIDOGLYCAN. CEFACLOR IS STABLE IN THE PRESENCE OF SOME BACTERIAL BETA-LACTAMASES; CONSEQUENTLY, SOME BETA-LACTAMASE-PRODUCING ORGANISMS MAY BE
SUSCEPTIBLE TO CEFACLOR.