Isolating and identifying the minimum inhibitory concentration of some antibiotics against Balantidium coli

Abstract

The objective of the study was to isolate and to determine the minimum inhibitory concentration (MIC) of halquinol,  Balantidium coli (B. coli). In this study, 20 isolates of B. coli were successfully isolated. Observing the bacteria culture process indicated that at 24 hours (h) after culture, the number of B. coli increased to a peak (CPM = 4.81 ± 0.52 log10), and then gradually decreased at 48 h (CPM = 4.14 ± 0.61 log10) post culture (P <0.05). The number of B. coli at the beginning of inoculation to the culture media reached CPM = 3.9 ± 0.25 log10 and significantly increased (P <0.05) higher than 1.0 log after 24 hours. At later time-points, B. coli number gradually decreased and rapidly
declined to terminate life cycle at 216 hours. Testing the inhibition of antibiotics for isolated B. coli strains showed that the MIC of paromomycin was (0.01 mg/ml), followed by halquinol (0.2 mg/ml), doxycycline (2.81 mg/ml) and oxytetracycline (3.06 mg/ml). Especially, the MIC of chlortetracycline for B. coli in this study was not determined, although the trial had 3 replications at high concentration (50 mg/ml). This is the first success in finding the growth curve of B. coli in artificial medium culture and determining the minimum inhibitory concentration (MIC) of the investigated antibiotics for B. coli.