墨西哥产超广谱β-内酰胺酶肠杆菌科儿科临床分离株中质粒介导喹诺酮耐药基因的特征。
Characterization of plasmid-mediated quinolone resistance (PMQR) genes in extended-spectrum β-lactamase-producing Enterobacteriaceae pediatric clinical isolates in Mexico.
机构信息
Instituto Nacional de Salud Pública, Centro de Investigación sobre Enfermedades Infecciosas (CISEI), Departamento de Diagnóstico Epidemiológico. Cuernavaca, Morelos, México.
出版信息
PLoS One. 2013 Oct 17;8(10):e77968. doi: 10.1371/journal.pone.0077968. eCollection 2013.
This work describes the characterization of plasmid-mediated quinolone-resistance (PMQR) genes from a multicenter study of ESBL-producing Enterobacteriaceae pediatric clinical isolates in Mexico. The PMQR gene-positive isolates were characterized with respect to ESBLs, and mutations in the GyrA and ParC proteins were determined. The phylogenetic relationship was established by PFGE and the transfer of PMQR genes was determined by mating assays. The prevalence of the PMQR genes was 32.1%, and the rate of qnr-positive isolates was 15.1%; 93.3% of the latter were qnrB and 6.4% were qnrA1. The distribution of isolates in terms of bacterial species was as follows: 23.5% (4/17) corresponded to E. cloacae, 13.7% (7/51) to K. pneumoniae, and 13.6% (6/44) to E. coli. In addition, the prevalence of aac(6')-Ib-cr and qepA was 15.1% and 1.7%, respectively. The molecular characteristics of qnr- and qepA-positive isolates pointed to extended-spectrum β-lactamase (ESBL) CTX-M-15 as the most prevalent one (70.5%), and to SHV-12 in the case of aac(6')-Ib-cr-positive isolates. GyrA mutations at codons Ser-83 and Asp-87, and ParC mutations at codons Ser-80 were observed in 41.1% and 35.2% of the qnr-positive isolates, respectively. The analysis of the transconjugants revealed a co-transmission of bla(CTX-M-15) with the qnrB alleles. In general, the prevalence of PMQR genes (qnr and aac(6')-Ib-cr) presented in this work was much lower in the pediatric isolates, in comparison to the adult isolates in Mexico. Also, ESBL CTX-M-15 was the main ESBL identified in the pediatric isolates, whereas in the adult ones, ESBLs corresponded to the CTX-M and the SHV families. In comparison with other studies, among the PMQR-genes identified in this study, the qnrB-alleles and the aac(6')-Ib-cr gene were the most prevalent, whereas the qnrS1, qnrA1 and qnrB-like alleles were the most prevalent in China and Uruguay.
这项工作描述了从墨西哥多中心产超广谱β-内酰胺酶（ESBL）肠杆菌科儿科临床分离株中对质粒介导的喹诺酮耐药（PMQR）基因的特征。对 PMQR 基因阳性分离株进行了 ESBL 特征分析，并确定了 GyrA 和 ParC 蛋白的突变。通过 PFGE 建立了系统发育关系，并通过交配试验确定了 PMQR 基因的转移。PMQR 基因的流行率为 32.1%，qnr 阳性分离株的比率为 15.1%；后者的 93.3%为 qnrB，6.4%为 qnrA1。根据细菌种类分布的分离株如下：23.5%（4/17）为阴沟肠杆菌，13.7%（7/51）为肺炎克雷伯菌，13.6%（6/44）为大肠埃希菌。此外，aac(6')-Ib-cr 和 qepA 的流行率分别为 15.1%和 1.7%。qnr-和 qepA 阳性分离株的分子特征表明，最常见的是扩展谱β-内酰胺酶（ESBL）CTX-M-15（70.5%），而 aac(6')-Ib-cr 阳性分离株为 SHV-12。qnr 阳性分离株中分别观察到 GyrA 密码子 Ser-83 和 Asp-87 以及 ParC 密码子 Ser-80 的突变，分别为 41.1%和 35.2%。转座子分析显示 bla(CTX-M-15)与 qnrB 等位基因的共转移。总的来说，与墨西哥成人分离株相比，本研究中小儿分离株中 PMQR 基因（qnr 和 aac(6')-Ib-cr）的流行率要低得多。此外，在儿科分离株中，主要的 ESBL 是 CTX-M-15，而在成人分离株中，ESBL 则属于 CTX-M 和 SHV 家族。与其他研究相比，在本研究中鉴定的 PMQR 基因中，qnrB 等位基因和 aac(6')-Ib-cr 基因最为流行，而 qnrS1、qnrA1 和 qnrB-like 等位基因在中国和乌拉圭最为流行。
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