In response to osmotic stress, gram positive bacteria Streptococcus agalactiae and enterobacteria Escherichia coli accumulates compatible solutes from the medium, stress response systems may enable bacteria to adapt cellular response and survival systems to a variety of stress conditions. S. agalactiae and E. coli strains have a transporter for carnitine that can respond to osmotic stress by regulating its own activity. Brain heart infusion (BHI) broth medium with 1 mM L-carnitine was the medium with the highest growth to be observed. The growth of the E. coli strain was faster than the growth of S. agalactiae strain. S. agalactiae and E. coli are known as bacteria being hard to grow at the laboratory tests for making clinical diagnosis. The medium with L-carnitine factor used in laboratory tests accelerates the bacterial growth.