passages.id: split_1_test_1869_passage
passages.type: progene_text
passages.text: Alone , colistin , ciprofloxacin , doxycycline , and tobramycin were moderately toxic at concentrations close to those used in cell culture , whereas amphotericin , ceftazidime , chloramphenicol , imipenem , meropenem , piperacillin , sulfamethoxazole / trimethoprim , and vancomycin were nontoxic even at concentrations many times the antimicrobial level .