Buyck J M, Luyckx C, Muccioli G G, Krause K M, Nichols W W, Tulkens P M, Van Bambeke F
Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.
MASSMET Platform, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.
J Antimicrob Chemother. 2017 May 1;72(5):1400-1409. doi: 10.1093/jac/dkw587.
When tested in broth, avibactam reverses ceftazidime resistance in many Pseudomonas aeruginosa that express ESBLs. We examined whether similar reversal is observed against intracellular forms of P. aeruginosa .
Strains: reference strains; two engineered strains with basal non-inducible expression of AmpC and their isogenic mutants with stably derepressed AmpC; and clinical isolates with complete, partial or no resistance to reversion with avibactam. Pharmacodynamic model: 24 h concentration-response to ceftazidime [0.01-200 mg/L alone or with avibactam (4 mg/L)] of bacteria in broth or bacteria phagocytosed by THP-1 monocytes, with calculation of ceftazidime relative potency ( C s : concentration yielding a static effect) and maximal relative effect [ E max : cfu decrease at infinitely large antibiotic concentrations (efficacy in the model)] using the Hill equation. Cellular content of avibactam: quantification by LC-MS/MS.
For both extracellular and intracellular bacteria, ceftazidime C s was always close to its MIC. For ceftazidime-resistant strains, avibactam addition shifted ceftazidime C s to values close to the MIC of the combination in broth. E max was systematically below the detection limit (-5 log 10 ) for extracellular bacteria, but limited to -1.3 log 10 for intracellular bacteria (except for two isolates) with no effect of avibactam. The cellular concentration of avibactam reflected extracellular concentration and was not influenced by ceftazidime (0-160 mg/L).
The potential for avibactam to inhibit β-lactamases does not differ for extracellular and intracellular forms of P. aeruginosa , denoting an unhindered access to its target in both situations. The loss of maximal relative efficacy of ceftazidime against intracellular P. aeruginosa was unrelated to resistance via avibactam-inhibitable β-lactamases.
在肉汤中进行测试时，阿维巴坦可逆转许多表达超广谱β-内酰胺酶（ESBLs）的铜绿假单胞菌对头孢他啶的耐药性。我们研究了针对铜绿假单胞菌的细胞内形式是否观察到类似的逆转情况。
菌株：参考菌株；两种具有基础非诱导性AmpC表达的工程菌株及其AmpC稳定去阻遏的同基因突变体；以及对阿维巴坦逆转耐药性完全、部分或无耐药性的临床分离株。药效学模型：计算肉汤中细菌或被THP-1单核细胞吞噬的细菌对头孢他啶[单独使用浓度为0.01 - 200mg/L或与阿维巴坦（4mg/L）联合使用]的24小时浓度-反应，使用希尔方程计算头孢他啶相对效价（Cs：产生静态效应的浓度）和最大相对效应[Emax：在无限大抗生素浓度下的cfu减少量（模型中的疗效）]。阿维巴坦的细胞含量：通过LC-MS/MS定量。
对于细胞外和细胞内细菌，头孢他啶的Cs始终接近其最低抑菌浓度（MIC）。对于耐头孢他啶菌株，添加阿维巴坦可使头孢他啶的Cs值接近肉汤中联合用药的MIC。对于细胞外细菌，Emax系统地低于检测限（-5 log10），但对于细胞内细菌（除两个分离株外），Emax限于-1.3 log10，且阿维巴坦无影响。阿维巴坦的细胞浓度反映细胞外浓度，且不受头孢他啶（0 - 160mg/L）影响。
阿维巴坦抑制β-内酰胺酶的潜力在铜绿假单胞菌的细胞外和细胞内形式中没有差异，这表明在两种情况下均可无障碍地作用于其靶点。头孢他啶对细胞内铜绿假单胞菌最大相对疗效的丧失与通过阿维巴坦可抑制的β-内酰胺酶介导的耐药性无关。
