Teuber M
J Bacteriol. 1969 May;98(2):347-50. doi: 10.1128/jb.98.2.347-350.1969.
A polymyxin B-resistant strain of Proteus mirabilis was converted into L forms and spheroplasts in the presence of penicillin G. This treatment caused a 400-fold increase in polymyxin B susceptibility. The acquired susceptibility was in the range of the natural susceptibility reported for susceptible gram-negative bacteria ( approximately 1 mug/ml). The high susceptibility to polymyxin B was lost as soon as the spheroplasts and L forms were allowed to reconvert into the bacillary form in penicillin-free media. This behavior is strong evidence that the natural resistance of Proteus strains to polymyxins is due to the impermeability of the outer cell wall structures to these antibiotic substances.
一株奇异变形杆菌的多粘菌素B耐药菌株在青霉素G存在的情况下被转化为L型和原生质体。这种处理使多粘菌素B敏感性增加了400倍。获得的敏感性处于对敏感革兰氏阴性菌报道的天然敏感性范围内(约1微克/毫升)。一旦原生质体和L型在无青霉素的培养基中重新转化为杆菌形式,对多粘菌素B的高敏感性就会丧失。这种现象有力地证明,变形杆菌菌株对多粘菌素的天然耐药性是由于外细胞壁结构对这些抗生素物质的不透性所致。