Selective Liquid Media for Coagulase-positive Staphylococci

Abstract

Three selective liquid media were tested. In Mannitol Salt Broth, the growth of Coagulase-positive Staphylococci (CPS) was poor. And the medium was not effective for inhibition of growth of Bacillus subtilis and B. licheniformis.In Potassium tellurite 7.5% NaCl Mannitol Broth (TSMB), the growth of CPS was same as in Mannitol Salt Broth. Although the growth of Coagulase-negative Staphylococci (CNS) retarded somewhat in this medium, B. subtilis and B. licheniformis grew more slowly than CPS.The growth of CPS, CNS, B. subtilis and B. licheniformis were accelerated by addition of 1.0g of agar-agar to 1, 000ml of TSMB. But CPS were distinguished by black clouding around the colonies from other organisms at the incubation of 48 hours at 37°C. Even CNS and B. subtilis produced similar black clouding after additional incubation.