Definition of polymyxin in English:


Pronunciation /ˌpälēˈmiksən/ /ˌpɑliˈmɪksən/


  • Any of a group of polypeptide antibiotics that are active chiefly against Gram-negative bacteria.

    Polymyxins are obtained from soil bacteria of the genus Bacillus, in particular B. polymyxa

    ‘If the area of affected skin is limited, mupirocin is an effective topical therapy; it was more effective than the other topical antibiotics studied (i.e., neomycin, bacitracin, polymyxin B, and gentamicin).’
    • ‘Results of randomized studies assessing the efficacy of triple antibiotic ointment (e.g., polymyxin, bacitracin and neomycin) are indeterminate.’
    • ‘The vaccine contains lyophilized calf lymph and traces of polymyxin B, streptomycin, tetracycline, and neomycin.’
    • ‘If you are having chemotherapy, or if your immune system is low for another reason, or if you are allergic to the drugs neomycin or polymyxin, you should not have the rubella vaccination.’
    • ‘Polymyxin B was used as a control agent because it is well known that polymyxins have direct antimicrobial activity and bind stoichiometrically to the lipid A moiety of bacterial LPS.’


1940s from modern Latin polymyxa, from Greek polu- ‘much’ + muxa ‘slime’+ -in.