ABSTRACT
The objective of this study was to investigate the risk of attenuated efficacy due to adaptive resistance for the siderophore-conjugated monocarbam SMC-3176 in
Pseudomonas aeruginosa
by using a pharmacokinetic/pharmacodynamic (PK/PD) approach. MICs were determined in cation-adjusted Mueller-Hinton broth (MHB) and in Chelex-treated, dialyzed MHB (CDMHB). Spontaneous resistance was assessed at 2× to 16× the MIC and the resulting mutants sequenced. Efficacy was evaluated in a neutropenic mouse thigh model at 3.13 to 400 mg/kg of body weight every 3 h for 24 h and analyzed for association with free time above the MIC (
fT
>MIC). To closer emulate the conditions of the
in vivo
model, we developed a novel assay testing activity mouse whole blood (WB). All mutations were found in genes related to iron uptake:
piuA
,
piuC
,
pirR
,
fecI
, and
pvdS
. Against four
P. aeruginosa
isolates, SMC-3176 displayed predictable efficacy corresponding to the
fT
>MIC using the MIC in CDMHB (
R
2
= 0.968 to 0.985), with stasis to 2-log kill achieved at 59.4 to 81.1%. Efficacy did not translate for
P. aeruginosa
isolate JJ 4-36, as the
in vivo
responses were inconsistent with
fT
>MIC exposures and implied a threshold concentration that was greater than the MIC. The results of the mouse WB assay indicated that efficacy was not predictable using the MIC for JJ 4-36 and four additional isolates, against which
in vivo
failures of another siderophore-conjugated β-lactam were previously reported. SMC-3176 carries a risk of attenuated efficacy in
P. aeruginosa
due to rapid adaptive resistance preventing entry via the siderophore-mediated iron uptake systems. Substantial
in vivo
testing is warranted for compounds using the siderophore approach to thoroughly screen for this
in vitro-in vivo
disconnect in
P. aeruginosa
.
摘要
本研究的目的是调查苷元结合单卡巴姆 SMC-3176 在铜绿假单胞菌中的适应性抗药性导致药效减弱的风险。
铜绿假单胞菌
采用药代动力学/药效学(PK/PD)方法。在阳离子调整的穆勒-希顿肉汤(MHB)和经 Chelex 处理的透析 MHB(CDMHB)中测定了 MIC。在 MIC 为 2 倍至 16 倍时对自发耐药性进行评估,并对由此产生的突变体进行测序。在嗜中性粒细胞病小鼠大腿模型中,以每公斤体重 3.13 至 400 毫克的剂量,每 3 小时注射一次,连续注射 24 小时,对药效进行了评估,并分析了药效与高于 MIC 的自由时间(fT)的关系。
fT
MIC)的相关性进行分析。为了更接近
体内
模型的条件,我们开发了一种检测小鼠全血(WB)活性的新型检测方法。所有突变都发生在与铁吸收有关的基因中:
piuA
,
piuC
,
pirR
,
fecI
和
pvdS
.针对四种
铜绿假单胞菌
分离物,SMC-3176 显示出与
fT
>MIC(使用 CDMHB 中的 MIC (
R
2
= 0.968 到 0.985),59.4% 到 81.1%的杀灭率达到 2-log。对于
绿脓杆菌
分离物 JJ 4-36 的疗效没有转化为
体内
反应与
fT
>MIC 暴露不一致,这意味着阈值浓度高于 MIC。小鼠 WB 检测结果表明,使用 JJ 4-36 和另外四种分离物的 MIC 无法预测药效。
体内
此前曾有报道称,另一种苷元结合的 β-内酰胺类药物对这四种分离物的体内疗效不佳。SMC-3176 对铜绿假单胞菌的疗效可能会减弱。
铜绿假单胞菌
SMC-3176 在铜绿假单胞菌中的疗效可能会减弱,因为快速的适应性抗药性会阻止其通过嗜苷铁元素介导的铁吸收系统进入体内。在
体内
测试,以彻底筛查这种 "体外-体内 "试验。
体外-体内
铜绿假单胞菌
铜绿假单胞菌
.