Molecular epidemiological study for the invasive infections due to Group A streptococci

在日本侵袭性链球菌感染的调查中，我们分析了1992至1994年间收集的化脓性链球菌分离株。用计算机辅助分析比较脉冲场凝胶电泳(PFGE)产生的基因组DNA指纹图谱。在42株侵袭性疾病患者分离的菌株中，共鉴定出16种PFGE分型，且具有明显的遗传多样性。在侵袭性和非侵袭性分离株中观察到相同的指纹。只有43%的侵袭性分离株产生链球菌热原外毒素A(Spe A)，31%的菌株不含spe A基因。这些发现表明，一个特定克隆的传播不足以解释日本所有这些疾病的病例，并对SPE A作为主要致病因子的作用提出了疑问。我们还观察到4例这种微生物在侵袭性疾病患者及其家人之间的传播。通过对回收的分离株基因组DNA指纹图谱分析，证实了克隆传播在家庭成员中的存在。虽然14人仅导致殖民者或自闭性疾病，但3人发展为侵袭性感染。我们的研究结果表明，对侵袭性链球菌疾病患者的密切接触者需要进行抗生素化学预防。

In a survey of invasive streptococcal infections in Japan, we analyzed isolates of Streptococcus pyogenes collected between 1992 and 1994. Genomic DNA fingerprints produced by pulsed-field gel electrophoresis (PFGE) were compared by computer-assisted analysis. Among the 42 isolates from patients with invasive diseases, 16 PFGE-types were identified and genetic diversity was clearly demonstrated. Identical fingerprints were observed in both invasive and noninvasive isolates. Only 43% of invasive isolates produced streptococcal pyrogenic exotoxin A (SPE A) and 31% did not contain the spe A gene. These findings suggest that the dissemination of a specific clone is not sufficient to explain all cases of these diseases in Japan, and pose a question to the role of SPE A as a major virulent factor.We have also observed 4 cases of transmission of this organism among a patient with invasive disease and his or her family members. The clonal spread among the family members was confirmed by analyzing genomic DNA fingerprints of the isolates recovered from them. Although 14 persons resulted in only colonizers or self-limitted diseases, 3 developed invasive infections. Our findings indicate the need of antibiotic chemoprophylaxis for close contacts of patients with invasive streptococcal diseases.