Sentence: To determine the long-term tolerability of prophylactic administration of pyrazinamide and levofloxacin in patients possibly exposed to multidrug-resistant tuberculosis ( MDRTB ) after undergoing solid organ transplantation .
Drug combination annotation:
[{'class': 'NEG', 'spans': ['pyrazinamide', 'levofloxacin'], 'is_context_needed': True}]