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

在日本的侵袭性链球菌感染调查中，我们分析了1992年至1994年间收集的化脓性链球菌分离株。通过计算机辅助分析，比较了脉冲场凝胶电泳（PFGE）产生的基因组DNA指纹图谱。在42株侵袭性疾病患者分离株中，鉴定出16种pfge型，遗传多样性明显。在侵入性和非侵入性分离株中观察到相同的指纹。只有43%的侵入性分离株产生链球菌热原外毒素A (SPE A)， 31%不含SPE A基因。这些发现表明，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作为主要致病因素的作用提出了质疑。我们还观察到4例该菌在侵袭性疾病患者及其家庭成员之间的传播。通过分析分离株的基因组DNA指纹图谱，证实了家族成员间的克隆传播。虽然有14人只感染了殖民者或自限性疾病，但有3人感染了侵入性感染。我们的研究结果表明，侵袭性链球菌疾病患者的密切接触者需要抗生素化学预防。

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.