Chapman J S, Bertasso A, Cummings L M, Georgopapadakou N H
Roche Research Center, Nutley, New Jersey 07110, USA.
Antimicrob Agents Chemother. 1995 Feb;39(2):564-6. doi: 10.1128/AAC.39.2.564.
Four spontaneous, single-step mutants of Escherichia coli K-12 resistant to low levels of the cephalosporin 3'-quinolone ester Ro 23-9424 were isolated at a frequency of 10(-10) to 10(-11) mutants per CFU plated. The mutants were cross-resistant to both cephalosporin (cefotaxime) and quinolone (fleroxacin) components. Accordingly, they had altered porins and replicative DNA biosynthesis resistant to fleroxacin. There was no increase in beta-lactamase activity when tested with nitrocephin, and the penicillin-binding protein profiles were normal.
以每平板接种的CFU产生10⁻¹⁰至10⁻¹¹个突变体的频率，分离出了4株对低水平头孢菌素3'-喹诺酮酯Ro 23-9424具有抗性的大肠杆菌K-12自发单步突变体。这些突变体对头孢菌素（头孢噻肟）和喹诺酮（氟罗沙星）成分均具有交叉抗性。因此，它们的孔蛋白发生了改变，并且复制性DNA生物合成对氟罗沙星具有抗性。用硝噻吩检测时，β-内酰胺酶活性没有增加，青霉素结合蛋白谱正常。
