In-Vitro Antimicrobial Activity of Membrane-Acting Antibiotics Action Against Streptococci

Streptococcus equi subS. equi a group C streptococcus is a gram-positive bacterium and is the causative agent of one of the most prevalent diseases of horses known as strangles, although, a live attenuated S. equi vaccine for prevention of the strangles has been introduced, there are presently still no proven vaccine against S. equi. In the effort to develop an effective vaccine against S. equi, the minimum inhibitory concentrations of antimicrobials acting bacterial membrane - triclosan and 4-Methylumbelliferone (4-MU) on S. equi have been investigated. These were determined by serial dilution technique on three strains of the equine S. equi: 4047, K3, and NCTC 9682. In addition, sensitive disk test on solid media were also carried out. The result of this study demonstrated that the three strains of S. equi are very sensitive to triclosan as they inhibit certain membrane functions. However, these strains are very resistant to 4-MU. Further research to investigate the mechanism of interaction between these antimicrobial agents and the bacterial membrane components is required.