Analysis of Invasive S. pneumoniae from Mali, Africa Usi

作为对马里巴马科儿科患者侵袭性感染正在进行的大规模研究的一部分，从2002年6月至2003年7月确定了106例侵袭性肺炎球菌病(IPD)病例。在现有的12个血清型中，大部分分离株没有包含在PCV7结合疫苗中，包括1个血清型1，12个血清2型，58个血清型5，7个血清型7F，1个血清型12F。为确定是否存在优势血清型的克隆性传播，对100株肺炎链球菌进行了基因分型：SmaI酶切基因组DNA的脉冲场凝胶电泳(PFGE)和使用肠球菌试剂盒的细菌条形码REP-PCR方法。建立了REP-PCR基因分型的标准，使得不同血清型的分离株通常不会被归类在一起。这两种方法在给定肺炎球菌血清型时具有同等的区分性。PFGE将菌株分为15个基因型和7个亚型，REP-PCR将菌株分为15个基因型和6个亚型。使用任何一种方法，血清型2、5和7型内的分离物形成了三个大的独立的簇，每个簇包含一个基因。这两种方法进一步区分了血清型2和血清型5的相关亚型。血清型5的一个PFGE亚型与1994年以来在拉丁美洲流行的哥伦比亚型5-19克隆没有区别。数据表明，血清型2和5型的优势很可能是克隆传播的结果，其中一些克隆导致了广泛人群范围内的侵袭性疾病。这些结果最近已提交发表。

As part of a large, ongoing study of invasive infections in pediatric patients in Bamako Mali, 106 cases of invasive pneumococcal disease (IPD) were identified from June 2002 to July 2003. Of the 12 serotypes present, the majority of isolates were not contained in the PCV7 conjugate vaccine, including 1 isolate that was serotype 1, 12 serotype 2, 58 serotype 5, 7 serotype 7F, and 1 serotype 12F. To determine if clonal dissemination of the predominant serotypes had taken place, genotyping was performed on 100 S. pneumoniae isolates using two methods: pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, and the Bacterial Barcodes rep-PCR method using the Enterococcus kit. Criteria for delineating rep-PCR genotypes were established such that isolates of different serotypes were generally not grouped together. The two methods were equally discriminatory within a given pneumococcal serotype. PFGE separated the isolates into 15 genotypes and 7 subtypes; rep-PCR separated isolates into 15 genotypes and 6 subtypes. Using either method, isolates within serotypes 2, 5, and 7 formed three large, separate clusters containing 1 genotype each. Both methods further distinguished related subtypes within serotypes 2 and 5. One of the PFGE subtypes of serotype 5 is indistinguishable from the Columbia5-19 clone circulating in Latin America since 1994. The data suggest that the predominance of serotypes 2 and 5 is likely the result of dissemination of clones, some of which are responsible for invasive diseases over a broad population range. These results have recently been submitted for publication.