Sentence: No synergism was found against Pneumococci and Meningococci but also no antagonism of the lower MIC and MBC values seen with ampicillin and penicillin G. The combination of chloramphenicol with either penicillin or ampicillin constitutes a clinically successful therapeutic regimen which is now also proven by in vitro investigations .
Drug combination annotation:
[{'class': 'COMB', 'spans': ['ampicillin', 'penicillin'], 'is_context_needed': True}, {'class': 'POS', 'spans': [1, 4], 'is_context_needed': False}, {'class': 'POS', 'spans': [1, 2], 'is_context_needed': False}]