Macrolide resistance in Campylobacter jejuni and Campylobacter coli:: Molecular mechanism and stability of the resistance phenotype
Macrolide resistance in Campylobacter jejuni and Campylobacter coli:: Molecular mechanism and stability of the resistance phenotype
复制标题
DOI：
10.1128/aac.49.7.2753-2759.2005
复制
发表时间：
2005-07-01
影响因子：
4.9
通讯作者：
Taylor, DE
中科院分区：
文献类型：
--
作者：
Gibreel, A;Kos, VN;Taylor, DE
对来自不同地区的23株大环内酯类耐药弯曲杆菌进行了调查，以确定其耐大环内酯类抗生素的机制和稳定性。根据马尿酸生化试验的结果，以及五种基于PCR的基因分型方法，这些分离株被鉴定为空肠弯曲菌或结肠弯曲菌。在23S rRNA基因结构域V的两个位置发现了3个点突变。约78%的耐药菌株在其23S rRNA基因的等值碱基2059处发生了A>；G转换。具有该突变的菌株对红霉素和克拉霉素的最低抑菌浓度范围很广。因此，在感染耐药弯曲杆菌菌株的人群中，这种突变可能会导致治疗失败的可能性更大。在大约13%的分离物中检测到了另一个与大环内酯类相关的突变(A->；C颠换)，该突变位于大肠杆菌相当于碱基2058处。在所研究的一株空肠弯曲菌中，还发现了与幽门螺杆菌中常见的A2142G突变同源的位置与E.Coli23S rRNA碱基2058同源的A-GT；G转换。在大多数空肠弯曲菌分离株中，23S rRNA基因的突变是纯合的，但有两例在目标基因的三个拷贝中的两个拷贝中发现突变。自然转化证明了大环内酯类抗药性表型从一个耐药的弯曲杆菌菌株转移到一个敏感的弯曲杆菌菌株。含有A-2058->；C或A-2059->；G突变的转化子的生长速度与亲本菌株相似。7株代表菌株中有6株在无红霉素选择压力的条件下继代培养后，无论抗性水平、突变位置或目的基因突变拷贝数多少，红霉素抗性都是稳定的。1株A-2058->；G突变空肠弯曲菌在无红霉素培养基上传代55次后恢复对红霉素和克拉霉素的敏感性。对5株具有代表性的空肠弯曲菌和大肠埃希菌的核糖体蛋白L4和L22进行了序列分析，发现L4和L22蛋白在大环内酯类耐药相关蛋白中没有明显的变化，这可能是大环内酯类耐药或耐药水平增强的原因。
A collection of 23 macrolide-resistant Campylobacter isolates from different geographic areas was investigated to determine the mechanism and stability of macrolide resistance. The isolates were identified as Campylobacter jejuni or Campylobacter coli based on the results of the hippurate biochemical test in addition to five PCR-based genotypic methods. Three point mutations at two positions within the peptidyl transferase region in domain V of the 23S rRNA gene were identified. About 78% of the resistant isolates exhibited an A -> G transition at Escherichia coli equivalent base 2059 of the 23S rRNA gene. The isolates possessing this mutation showed a wide range of erythromycin and clarithromycin MICs. Thus, this mutation may incur a greater probability of treatment failure in populations infected by resistant Campylobacter isolates. Another macrolide-associated mutation (A -> C transversion), at E. coli equivalent base 2058, was detected in about 13% of the isolates. An A -> G transition at a position cognate with E. coli 23S rRNA base 2058, which is homologous to the A2142G mutation commonly described in Helicobacter pylori, was also identified in one of the C. jejuni isolates examined. In the majority of C. jejuni isolates, the mutations in the 23S rRNA gene were homozygous except in two cases where the mutation was found in two of the three copies of the target gene. Natural transformation demonstrated the transfer of the macrolide resistance phenotype from a resistant Campylobacter isolate to a susceptible Campylobacter isolate. Growth rates of the resulting transformants containing A-2058 -> C or A-2059 -> G mutations were similar to that of the parental isolate. The erythromycin resistance of six of seven representative isolates was found to be stable after successive subculturing in the absence of erythromycin selection pressure regardless of the resistance level, the position of the mutation, or the number of the mutated copies of the target gene. One C. jejuni isolate showing an A-2058 -> G mutation, however, reverted to erythromycin and clarithromycin susceptibility after 55 subcultures on erythromycin-free medium. Investigation of ribosomal proteins L4 and L22 by sequence analysis in five representative isolates of C. Jejuni and C. coli demonstrated no significant macrolide resistance-associated alterations in either the L4 or the L22 protein that might explain either macrolide resistance or enhancement of the resistance level.