Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) is a multi-drug resistant
bacteria that has a thinning reservoir of drugs effective against the numerous clinical
problems associated with it. A recent study established the presence of antimicrobial
activity of a tetramic acid antibiotic, Trichosetin, against a foreign strain of MRSA
(ATCC 33591).
This study aimed to determine the presence of antimicrobial property of
Trichosetin against clinical MRSA strains isolated in the Philippines by finding the
minimum inhibitory concentration (MIC). Using the National Committee for Clinical
Laboratory Standards protocol for microtiter-based MIC assay, the antimicrobial activity
of Trichosetin against nine local clinical MRSA isolates was evaluated. The solvent of
Trichosetin which is methanol was also screened against the MRSA isolates. The positive
control used was Vancomycin HCI. Results showed that Trichosetin manifested a strong
antimicrobial activity against MRSA isolates 1, 2, 3, 5, 6, 7, and 8, with MIC of
0.78 pg/ml, 5.72 pg/ml, 6.51 pg/ml, 0.78 pg/ml, 0.78 pg/ml, 0.78 pg/ml and 1.82 pg/ml,
respectively. It also showed a moderate inhibitory activity against the MRSA strains
4 and 9 with MIC of 12.76 pg/ml and 33.33 pg/ml. Statistical analyses have shown that
the differences between the nine local clinical MRSA isolates, and the difference between
the inhibitory activities of Trichosetin and Vancomycin have a significant effect on the
study.
