further comparative tests were also carried out with ampicillin , chloramphenicol , colistin sulphate , colistin methane sulphonate , cycloserine , kanamycin , nitrofurantoin , polymyxin , streptomycin , and tetracycline , using groups of 20 strains of each of the main species selected at random from the total number of isolates .
C0009316
colistin
C0032539
polymyxin