Pengaruh pemberian rifampisin pada peningkatan kepekaan Staphylococcus aureus terhadap tetrasiklin

ABSTRACT Bacterial resistance to antibiotics has been an important problem worldwide. Discoveries and clinical use of new antibiotics have always been followed by emergence of strains of bacterial resistant to the antibiotics in question within relatively short period of time. Various efforts have been attempted to overcome the problem, one of which being the use of two or more different antibiotics in combination. In this study the effect of rifampicin on alternation of susceptibility of S. aureus to tetracycline was evaluated. Sixty seven isolates of tetracycline resistant S. aureus determined by standard disk diffusion method of Kirby-Bauer were collected during the period from August 1997 to January 1998. Minimal Inhibitory Concentration (MIC = KHM) values of rifampicin for this isolates were determined by broth dilution method. MIC of tetracycline for each isolate was determined while the bacteria were exposed to rifampicin at sub MIC. At the same time determination of the MIC was also performed without exposing the bacteria to rifampicin and this procedure served as control. Results showed that 91% (61 of 67) rifampicin - exposed isolates have increase susceptibility to tetracycline as reflected by the decrease of MIC values. It is concluded that there is synergistic effects of tetracycline and rifampicin on S. aureus. The number of isolate with increased susceptibility to tetracycline during exposure to rifampicin was statistically significant (p < 0.05). Key Words : rifampicin - Staphylococcus aureus - susceptibility - tetracycline Resistensi bakteri terhadap antibiotika merupakan masalah besar di dunia. Berbagai penemuan antibiotika baru selalu diikutl timbulnya strain-strain bakteri yang resisten dalam waktu yang relatif singkat. Berbagai upaya telah dilakukan untuk mengurangl resistensi, salah satu dl antaranya adalah penggunaan kombinasi antibiotik. Pada penelitlan inl telah dilakukan pengujian pengaruh pemberlan rifampisin pada peningkatan kepekaan S. aureus terhadap tetrasiklln. Sejak Agustus 1997 sampal Januari 1998 di Laboratorium Mikrobiologi FK UGM, berhasil dilsolasi 67 isolat S. aureus yang resisten tetrasiklin dengan menggunakan metode cakram Kirby-Bauer. Masing-masing isolat dicari Kadar Hambat Minimum (KHM = MIC) terhadap rifampisin dengan metode dilusi cair. KHM terhadap tetrasiklin masing-masing Isolat dicari setelah pemaparan rifampisin sub KHM. Pada waktu yang bersamaan nilai KHM tetrasiklin tanpa pemberian rifampisin juga dicari dan digunakan sebagai kontrol. Dad 67 isolat yang diperiksa, 61 (91%) isolat di antaranya menunjukkan peningkatan kepekaan terhadap tetrasiklin yang dItandai dengan penurunan nilal KHM. Hal ini menunjukkan bahwa terdapat efek sinergistik tetrasiklin dan rifampisln. Jumlah isolat yang menunjukkan peningkatan kepekaan terhadap tetrasiklin setelah pemaparan rifampisin sub KHM bermakna secara statistlk (p < 0,05