南非爆发的李斯特菌感染与加工肉类有关，这一成果由南非国家卫生实验局Juno Thomas研究组取得。2020年2月13日出版的《新英格兰医学杂志》发表了这项成果。

2017年在南非爆发了一场来源不明的李斯特菌感染。

研究组进行了流行病学、回溯和环境调查，并采用全基因组测序对单核细胞增生李斯特菌分离株进行了分型。2017年6月11日至2018年4月7日，实验室确认1例单核细胞增生李斯特菌感染。

共发现937例感染，其中465例（50%）妊娠相关，406例（87%）为感染孕妇生的新生儿。229例（24%）年龄在15岁至49岁之间（不包括孕妇）。在已知人类免疫缺陷病毒（HIV）感染的患者中，38%妊娠相关者和46%其余患者均为HIV阳性。

728名患者中有193名（27%）死亡。对609例患者的临床分离株进行了测序，567例（93%）被鉴定为6型序列（ST6）。在病例对照分析中，与非ST6感染者相比，ST6感染者中有很多人食用了香肠，优势比为8.55。

香肠和环境样本也分离出了ST6菌株，这些菌株与患者的菌株属于同一核心基因组多位点序列分型簇，差异不超过4个等位基因；这些发现表明，在单独机构生产的香肠是疫情源头。从该工厂召回香肠后，单核细胞增生李斯特菌ST6感染率迅速下降。

总之，在一个艾滋病感染率很高的中等收入国家，单核细胞增生李斯特菌在年轻孕妇、 妇女和艾滋病感染者中的感染率很高。全基因组测序有助于发现疫情，指导回溯调查，从而锁定源头。

附：英文原文

Title: Outbreak of Listeriosis in South Africa Associated with Processed Meat

Author: Juno Thomas, M.D.,, Nevashan Govender, M.Sc., M.P.H.,, Kerrigan M. McCarthy, M.D.,, Linda K. Erasmus, M.D.,, Timothy J. Doyle, Ph.D.,, Mushal Allam, Ph.D.,, Arshad Ismail, Ph.D.,, Ntsieni Ramalwa, M.P.H.,, Phuti Sekwadi, M.P.H.,, Genevie Ntshoe, M.P.H.,, Andronica Shonhiwa, M.P.H.,, Vivien Essel, M.D.,, Nomsa Tau, M.S.,, Shannon Smouse, M.S.,, Hlengiwe M. Ngomane, M.T.,, Bolele Disenyeng, M.T.,, Nicola A. Page, Ph.D.,, Nelesh P. Govender, M.D.,, Adriano G. Duse, M.D.,, Rob Stewart, M.T.,, Teena Thomas, M.D.,, Deon Mahoney, M.S.,, Mathieu Tourdjman, M.D.,, Olivier Disson, Ph.D.,, Pierre Thouvenot, B.S.,, Mylène M. Maury, Ph.D.,, Alexandre Leclercq, M.S.,, Marc Lecuit, M.D., Ph.D.,, Anthony M. Smith, Ph.D.,, and Lucille H. Blumberg, M.D.

Issue&Volume: 2020-02-12

Abstract:

Background

An outbreak of listeriosis was identified in South Africa in 2017. The source was unknown.

Methods

We conducted epidemiologic, trace-back, and environmental investigations and used whole-genome sequencing to type Listeria monocytogenes isolates. A case was defined as laboratory-confirmed L. monocytogenes infection during the period from June 11, 2017, to April 7, 2018.

Results

A total of 937 cases were identified, of which 465 (50%) were associated with pregnancy; 406 of the pregnancy-associated cases (87%) occurred in neonates. Of the 937 cases, 229 (24%) occurred in patients 15 to 49 years of age (excluding those who were pregnant). Among the patients in whom human immunodeficiency virus (HIV) status was known, 38% of those with pregnancy-associated cases (77 of 204) and 46% of the remaining patients (97 of 211) were infected with HIV. Among 728 patients with a known outcome, 193 (27%) died. Clinical isolates from 609 patients were sequenced, and 567 (93%) were identified as sequence type 6 (ST6). In a case–control analysis, patients with ST6 infections were more likely to have eaten polony (a ready-to-eat processed meat) than those with non-ST6 infections (odds ratio, 8.55; 95% confidence interval, 1.66 to 43.35). Polony and environmental samples also yielded ST6 isolates, which, together with the isolates from the patients, belonged to the same core-genome multilocus sequence typing cluster with no more than 4 allelic differences; these findings showed that polony produced at a single facility was the outbreak source. A recall of ready-to-eat processed meat products from this facility was associated with a rapid decline in the incidence of L. monocytogenes ST6 infections.

Conclusions

This investigation showed that in a middle-income country with a high prevalence of HIV infection, L. monocytogenes caused disproportionate illness among pregnant girls and women and HIV-infected persons. Whole-genome sequencing facilitated the detection of the outbreak and guided the trace-back investigations that led to the identification of the source.

DOI: 10.1056/NEJMoa1907462

Source: https://www.nejm.org/doi/full/10.1056/NEJMoa1907462