Chen Mingliang, Wang Wenqing, Tu Lihong, Zheng Yaxu, Pan Hao, Wang Gangyi, Chen Yanxin, Zhang Xi, Zhu Linying, Chen Jian, Chen Min
Shanghai Municipal Center for Disease Control and PreventionShanghai, China.
Shanghai Institutes of Preventive MedicineShanghai, China.
Front Microbiol. 2017 Jun 21;8:1156. doi: 10.3389/fmicb.2017.01156. eCollection 2017.
Ranked among the top10 infectious causes of death worldwide, group A (GAS) causes small- and large-scale outbreaks, depending on the trigger as transmission of a GAS strain or expansion of predominant clones. In China, GAS infections other than scarlet fever are not notifiable. In Shanghai, an epidemiological investigation was initiated after two successive severe pneumonia cases with one death in a digital factory, from where outbreaks are less widely reported. The investigation was performed using typing, pulsed-field gel electrophoresis (PFGE) typing, superantigen profiling, and genome analysis. This enabled characterization of relatedness among the outbreak isolates and identification of the mobile genetic elements present. Among 57 patients with respiratory symptoms investigated in the factory, 5 GAS strains were isolated from 8 patients. The eight GAS infection cases comprising one fatal severe pneumonia case, six influenza-like illness cases, and one pharyngitis case. Two risk factors were identified: adult with an age of 18-20 years and close contact with a GAS patient or carrier. GAS attack rate was 14.0% (8/57), and GAS carriage rate was probably around 2.7% (14/521) based on surveys in two nearby districts. All the 10 outbreak associated isolates were assigned to 5 and sequence type ST-99 (5/ST-99), harbored superantigen genes , and , and were assigned to two similar PFGE patterns (clones). Among the outbreak associated isolates, all carried with resistance to erythromycin and inducible resistance to clindamycin, and eight (80%) carried a gene with resistance to tetracycline. Among the 14 carriage isolates, 12 were 12/ST-36, and 2 were 1/ST-28, all with superantigen genes , and . All the carriage isolates harbored and with resistance to erythromycin, clindamycin, and tetracycline. Genome analysis showed the two outbreak clones were closely related and possessed new prophages carrying virulence gene and antibiotic resistance genes of and , which were not found in the 5 reference strain Manfredo. This is the first report of a GAS outbreak in this type of workplace. The outbreak was caused by two closely related 5 clones that differed from the predominant types circulating in China.
A组链球菌（GAS）是全球十大传染性死因之一，会引发小规模和大规模疫情，具体取决于触发因素，如GAS菌株的传播或优势克隆的扩增。在中国，除猩红热外，GAS感染无需上报。在上海，一家数码工厂接连出现两例严重肺炎病例，其中一例死亡，随后展开了流行病学调查，此类工厂爆发疫情的报告较少。调查采用了分型、脉冲场凝胶电泳（PFGE）分型、超抗原分析和基因组分析。这有助于对疫情分离株之间的相关性进行表征，并识别存在的移动遗传元件。在该工厂调查的57例有呼吸道症状的患者中，从8例患者中分离出5株GAS菌株。这8例GAS感染病例包括1例致命的严重肺炎病例、6例流感样疾病病例和1例咽炎病例。确定了两个风险因素：年龄在18至20岁的成年人以及与GAS患者或携带者密切接触。GAS攻击率为14.0%（8/57），根据附近两个区的调查，GAS携带率可能约为2.7%（14/521）。所有10株与疫情相关的分离株被分为5种序列型，其中序列型ST-99有5株（5/ST-99），携带超抗原基因 、 ，并被分为两种相似的PFGE模式（克隆）。在与疫情相关的分离株中，所有菌株均携带 ，对红霉素耐药且对克林霉素有诱导性耐药，8株（80%）携带 基因，对四环素耐药。在14株携带菌株中，12株为序列型ST-36（12/ST-36），2株为序列型ST-28（1/ST-28），均携带超抗原基因 、 。所有携带菌株均携带 ，对红霉素、克林霉素和四环素耐药。基因组分析表明，两个疫情克隆密切相关，拥有携带毒力基因 以及 、 抗生素耐药基因的新噬菌体，在5株参考菌株曼弗雷多中未发现这些基因。这是此类工作场所GAS疫情的首次报告。此次疫情由两个密切相关的5克隆引起，它们与中国流行的主要 类型不同。
