OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs
OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs
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DOI：
10.1128/msphere.00024-19
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发表时间：
2019-03-01
期刊：
影响因子：
4.8
通讯作者：
Samuelsen, Orjan
中科院分区：
文献类型：
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作者：
Frohlich, Christopher;Sorum, Vidar;Samuelsen, Orjan
产碳青霉烯酶革兰氏阴性病原体引起的感染与有限的治疗选择相关，因此导致死亡率和发病率增加。作为回应，已开发了现有β-内酰胺类药物和新型β-内酰胺酶抑制剂（如头孢他啶-阿维巴坦（CAZ-AVI））的组合作为替代治疗选择。为了了解CAZ-AVI暴露下耐药性的发展和进化轨迹，我们研究了头孢他啶（CAZ）和CAZ-AVI对大肠杆菌中碳青霉烯酶OXA-48和流行性OXA-48质粒的影响。CAZ和CAZ-AVI的暴露分别导致OXA-48中的单（P68 A）和双（P68 A，Y211 S）氨基酸取代。药敏试验和酶动力学分析表明，P68 A取代导致对CAZ的抑制活性增加，而P68 A、Y211 S取代导致对AVI的抑制活性降低。突变体的X射线晶体学和分子建模表明活性位点内的灵活性增加，这可以解释CAZ水解升高和AVI抑制活性降低的原因。有趣的是，这些取代导致了损害OXA-48对碳青霉烯类和青霉素类活性的附带效应。此外，暴露于CAZ-AVI选择了OXA-48编码质粒内的突变，这些突变在没有抗菌剂选择的情况下严重降低了适应性。这些进化的权衡可能有助于限制OXA-48介导的CAZ和CAZ-AVI耐药性的进化，以及潜在的重新敏感的分离株对其他治疗alternatives.IMPORTANCE最近推出的新型β-内酰胺/β-内酰胺酶抑制剂组合，如头孢他啶-阿维巴坦增加了我们治疗多重耐药革兰氏阴性菌，包括产碳青霉烯酶的肠球菌引起的感染的能力。然而，报告的头孢他啶-阿维巴坦耐药病例数量增加令人担忧。OXA-48是一种碳青霉烯酶，对头孢他啶无显著影响，但可被阿维巴坦抑制。由于携带OXA-48的分离株经常携带阿维巴坦可抑制的超广谱β-内酰胺酶，因此头孢他啶-阿维巴坦很可能用于治疗产OXA-48肠球菌引起的感染。我们的数据表明，暴露于头孢他啶-阿维巴坦可导致OXA-48发生变化，导致水解头孢他啶和耐受阿维巴坦抑制作用的能力增加。因此，应监测产OXA-48肠球菌对头孢他啶-阿维巴坦的耐药性。有趣的是，OXA-48中的氨基酸取代对其他β-内酰胺类药物的影响以及头孢他啶-阿维巴坦暴露对流行性OXA-48质粒的影响表明，头孢他啶-阿维巴坦耐药性的演变伴随着间接效应。
Infections due to carbapenemase-producing Gram-negative pathogens are associated with limited treatment options and consequently lead to increased mortality and morbidity. In response, combinations of existing beta-lactams and novel beta-lactamase inhibitors, such as ceftazidime-avibactam (CAZ-AVI), have been developed as alternative treatment options. To understand the development of resistance and evolutionary trajectories under CAZ-AVI exposure, we studied the effects of ceftazidime (CAZ) and CAZ-AVI on the carbapenemase OXA-48 and the epidemic OXA-48 plasmid in Escherichia coli. Exposure of CAZ and CAZ-AVI resulted in single (P68A) and double (P68A, Y211S) amino acid substitutions in OXA-48, respectively. The antimicrobial susceptibility data and enzyme kinetics showed that the P68A substitution was responsible for an increased activity toward CAZ, whereas P68A, Y211S led to a decrease in the inhibitory activity of AVI. X-ray crystallography and molecular modeling of the mutants demonstrated increased flexibility within the active site, which could explain the elevated CAZ hydrolysis and reduced inhibitory activity of AVI. Interestingly, these substitutions resulted in collateral effects compromising the activity of OXA-48 toward carbapenems and penicillins. Moreover, exposure to CAZ-AVI selected for mutations within the OXA-48-encoding plasmid that severely reduced fitness in the absence of antimicrobial selection. These evolutionary trade-offs may contribute to limit the evolution of OXA-48-mediated CAZ and CAZ-AVI resistance, as well as potentially resensitize isolates toward other therapeutic alternatives.IMPORTANCE The recent introduction of novel beta-lactam/beta-lactamase inhibitor combinations like ceftazidime-avibactam has increased our ability to treat infections caused by multidrug-resistant Gram-negative bacteria, including carbapenemase-producing Enterobacterales. However, the increasing number of cases of reported resistance to ceftazidime-avibactam is a concern. OXA-48 is a carbapenemase that has no significant effect on ceftazidime, but is inhibited by avibactam. Since isolates with OXA-48 frequently harbor extended-spectrum beta-lactamases that are inhibited by avibactam, it is likely that ceftazidime-avibactam will be used to treat infections caused by OXA-48-producing Enterobacterales. Our data show that exposure to ceftazidime-avibactam can lead to changes in OXA-48, resulting in increased ability to hydrolyze ceftazidime and withstand the inhibitory effect of avibactam. Thus, resistance toward ceftazidime-avibactam among OXA-48-producing Enterobacterales should be monitored. Interestingly, the compromising effect of the amino acid substitutions in OXA-48 on other beta-lactams and the effect of ceftazidime-avibactam exposure on the epidemic OXA-48 plasmid indicate that the evolution of ceftazidime-avibactam resistance comes with collateral effects.