Identification of Amino Acids Conferring High-Level Resistance to Expanded-Spectrum Cephalosporins in the penA Gene from Neisseria gonorrhoeae Strain H041
Identification of Amino Acids Conferring High-Level Resistance to Expanded-Spectrum Cephalosporins in the penA Gene from Neisseria gonorrhoeae Strain H041
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DOI：
10.1128/aac.00093-13
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发表时间：
2013-07-01
影响因子：
4.9
通讯作者：
Nicholas, Robert A.
中科院分区：
文献类型：
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作者：
Tomberg, Joshua;Unemo, Magnus;Nicholas, Robert A.
最近从日本鉴定出一种高水平头孢曲松耐药（MIC = 2 - 4 μ g/ml）的淋病奈瑟菌分离株（H 041），预示着头孢曲松作为淋球菌感染有效治疗的丧失。这是一个严重的问题，因为头孢曲松是一线经验性抗菌药物单药治疗的最后选择。来自H 041（penA 41）的佩纳基因是一种嵌合佩纳等位基因，与全球范围内赋予中等水平头孢菌素耐药性（Ceph（i））的嵌合等位基因相似，但与来自先前研究的Ceph（i）菌株35/02（penA 35）的嵌合佩纳基因相比，有13个额外突变。当转化到野生型菌株FA 19中时，penA 41等位基因分别使头孢曲松和头孢克肟的MIC增加300倍和570倍。为了了解高水平头孢曲松耐药的机制，并在潜在出现头孢曲松耐药期间改善监测和流行病学，我们试图确定penA 35中赋予头孢曲松高水平耐药的氨基酸改变的最小数量。使用限制性片段交换和定点诱变，我们确定了三个突变，A311 V，T316 P和T483 S，当纳入到镶嵌penA 35等位基因，赋予基本上所有的增加耐药性penA 41。A311 V和T316 P接近形成酰基-酶复合物的活性位点亲核试剂Ser 310，而Thr 483预计与β-内酰胺抗生素的羧酸酯相互作用。迄今为止，这三种突变仅在penA 41中被描述，但这些突变在其他嵌合等位基因中的传播将意味着头孢曲松作为淋球菌感染的有效治疗的终结。
The recent identification of a high-level-ceftriaxone-resistant (MIC = 2 to 4 mu g/ml) isolate of Neisseria gonorrhoeae from Japan (H041) portends the loss of ceftriaxone as an effective treatment for gonococcal infections. This is of grave concern because ceftriaxone is the last remaining option for first-line empirical antimicrobial monotherapy. The penA gene from H041 (penA41) is a mosaic penA allele similar to mosaic alleles conferring intermediate-level cephalosporin resistance (Ceph(i)) worldwide but has 13 additional mutations compared to the mosaic penA gene from the previously studied Ceph(i) strain 35/02 (penA35). When transformed into the wild-type strain FA19, the penA41 allele confers 300- and 570-fold increases in the MICs for ceftriaxone and cefixime, respectively. In order to understand the mechanisms involved in high-level ceftriaxone resistance and to improve surveillance and epidemiology during the potential emergence of ceftriaxone resistance, we sought to identify the minimum number of amino acid alterations above those in penA35 that confer high-level resistance to ceftriaxone. Using restriction fragment exchange and site-directed mutagenesis, we identified three mutations, A311V, T316P, and T483S, that, when incorporated into the mosaic penA35 allele, confer essentially all of the increased resistance of penA41. A311V and T316P are close to the active-site nucleophile Ser310 that forms the acyl-enzyme complex, while Thr483 is predicted to interact with the carboxylate of the beta-lactam antibiotic. These three mutations have thus far been described only for penA41, but dissemination of these mutations in other mosaic alleles would spell the end of ceftriaxone as an effective treatment for gonococcal infections.