Tybring L
Antimicrob Agents Chemother. 1975 Sep;8(3):266-70. doi: 10.1128/AAC.8.3.266.
Mecillinam (formerly called FL 1060), a novel 6beta-amidinopenicillanic acid derivative, showed markedly higher activity than ampicillin against clinical isolates of Enterobacteriaceae. The mode of action of mecillinam is different from that of ampicillin and consequently no intrinsic cross-resistance between the two antibiotics was observed. Mecillinam is inactivated by beta-lactamases but is generally more stable than ampicillin; thus an apparent cross-resistance exists for strong beta-lactamase producers. The protein binding was low and the activity was relatively independent of pH between 5.5 and 8.0. Slow-growing, insensitive variants of Escherichia coli could be selected but these were not stable. The frequency of insensitive variants was affected by the sodium chloride concentration in the medium.
美西林（曾称FL 1060）是一种新型的6β-脒基青霉烷酸衍生物，对肠杆菌科临床分离菌的活性明显高于氨苄西林。美西林的作用方式与氨苄西林不同，因此未观察到两种抗生素之间存在内在交叉耐药性。美西林可被β-内酰胺酶灭活，但通常比氨苄西林更稳定；因此，对于强β-内酰胺酶产生菌存在明显的交叉耐药性。其蛋白结合率低，在5.5至8.0的pH范围内活性相对独立于pH值。可选择出大肠杆菌生长缓慢的不敏感变异株，但这些变异株不稳定。不敏感变异株的频率受培养基中氯化钠浓度的影响。
