Objectives

We analysed national surveillance typing data of Shigella isolated from adult males with domestically acquired infection (a cohort largely consisting of men who have sex with men (MSM)) to establish whether multiple isolates from the same individual over time represented persistent carriage or re-infection.

Methods

We carried out a retrospective cohort study of adult males diagnosed with Shigella from 2004 to 2018. Median time intervals between multiple isolations of Shigella flexneri and S. sonnei were compared. Analysis of whole genome sequencing data provided strain discrimination at the single nucleotide level and was used to quantify the genetic distance among isolates. Maximum likelihood phylogenies were constructed to determine whether persistent carriage (characterized by multiple isolations of the same strain) or re-infection (characterized by multiple isolations of different strains) was best supported by the phylogenetic analysis. A comparison analysis was carried out using data linked to adult females with domestically acquired shigellosis.

Results

The number of men reporting multiple isolations of Shigella species was 165/4733 (3.5%) compared with 31/2423 (1.3%) females (p < 0.001). For isolate pairs from men associated with persistent carriage, the isolation time interval range was 6–176 days (median 23.5; IQR 8–70) and single nucleotide polymorphism (SNP) distance range was 0–7 SNPs (median 0.5; IQR 0–2). For those associated with re-infection, the isolation time interval was 34–2636 days (median 732; IQR 191–1258) and the SNP distance was 10–1462 SNPs (median 120; IQR 29–377).

Discussion

Multiple Shigella isolations in individuals with domestically acquired infections was more frequently observed in adult males than in adult females. Following the acute phase of infection, carriage can persist for months, and infection can recur within months, even with strains belonging to the same species and the same serotype. A combination of multiple sexual partners, persistent carriage following the acute phase of infection and evidence of recurrent re-infection is likely to contribute to sustained transmission in this population.

中文翻译：

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在英国报告国内获得性感染的成年男性中再次感染和持续携带志贺氏菌的证据。

目标

我们分析了从国内获得性感染的成年男性（主要由男男性行为者 (MSM) 组成的队列）中分离出的志贺氏菌的国家监测分型数据，以确定随着时间的推移，同一个体的多个分离株是否代表持续携带或再次感染.

方法

我们对2004 年至 2018 年诊断为志贺氏菌的成年男性进行了一项回顾性队列研究。比较了多次分离志贺氏菌和松内氏菌之间的中位时间间隔。全基因组测序数据的分析提供了单核苷酸水平的菌株区分，并用于量化分离株之间的遗传距离。构建最大似然系统发育以确定系统发育分析是否最好支持持续携带（以同一菌株的多次分离为特征）或再感染（以不同菌株的多次分离为特征）。使用与患有国内获得性志贺菌病的成年女性相关的数据进行了比较分析。

结果

报告多次分离志贺氏菌的男性人数为 165/4733 (3.5%)，而女性为 31/2423 (1.3%) (p < 0.001)。对于与持续携带相关的男性的分离对，隔离时间间隔范围为 6-176 天（中位数 23.5；IQR 8-70），单核苷酸多态性 (SNP) 距离范围为 0-7 个 SNP（中位数 0.5；IQR 0- 2）。对于与再感染相关的患者，隔离时间间隔为 34-2636 天（中位数 732；IQR 191-1258），SNP 距离为 10-1462 个 SNP（中位数 120；IQR 29-377）。

讨论

在国内获得性感染的个体中分离出多重志贺氏菌在成年男性中比在成年女性中更常见。在感染的急性期之后，携带可以持续数月，并且感染可以在数月内复发，即使是属于同一物种和同一血清型的菌株。多个性伴侣、感染急性期后的持续携带以及反复感染的证据可能导致该人群中的持续传播。