Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine , Stanford, California, USA.
Centers for Disease Control and Prevention , Atlanta, Georgia, USA.
mBio. 2023 Aug 31;14(4):e0117923. doi: 10.1128/mbio.01179-23. Epub 2023 Jul 28.
We performed whole-genome sequencing of 174 Typhi and 54 Paratyphi A isolates collected through prospective surveillance in the context of a phased typhoid conjugate vaccine introduction in Navi Mumbai, India. We investigate the temporal and geographical patterns of emergence and spread of antimicrobial resistance. We evaluated the relationship between the spatial distance between households and genetic clustering of isolates. Most isolates were non-susceptible to fluoroquinolones, with nearly 20% containing ≥3 quinolone resistance-determining region mutations. Two H58 isolates carried an IncX3 plasmid containing bla, associated with ceftriaxone resistance, suggesting that the ceftriaxone-resistant isolates from India independently evolved on multiple occasions. Among . Typhi, we identified two main clades circulating (2.2 and 4.3.1 [H58]); 2.2 isolates were closely related following a single introduction around 2007, whereas H58 isolates had been introduced multiple times to the city. Increasing geographic distance between isolates was strongly associated with genetic clustering (odds ratio [OR] = 0.72 per km; 95% credible interval [CrI]: 0.66-0.79). This effect was seen for distances up to 5 km (OR = 0.65 per km; 95% CrI: 0.59-0.73) but not seen for distances beyond 5 km (OR = 1.02 per km; 95% CrI: 0.83-1.26). There was a non-significant reduction in odds of clustering for pairs of isolates in vaccination communities compared with non-vaccination communities or mixed pairs compared with non-vaccination communities. Our findings indicate that . Typhi was repeatedly introduced into Navi Mumbai and then spread locally, with strong evidence of spatial genetic clustering. In addition to vaccination, local interventions to improve water and sanitation will be critical to interrupt transmission. IMPORTANCE Enteric fever remains a major public health concern in many low- and middle-income countries, as antimicrobial resistance (AMR) continues to emerge. Geographical patterns of typhoidal spread, critical to monitoring AMR and planning interventions, are poorly understood. We performed whole-genome sequencing of . Typhi and . Paratyphi A isolates collected in Navi Mumbai, India before and after a typhoid conjugate vaccine introduction. From timed phylogenies, we found two dominant circulating lineages of . Typhi in Navi Mumbai-lineage 2.2, which expanded following a single introduction a decade prior, and 4.3.1 (H58), which had been introduced repeatedly from other parts of India, frequently containing "triple mutations" conferring high-level ciprofloxacin resistance. Using Bayesian hierarchical statistical models, we found that spatial distance between cases was strongly associated with genetic clustering at a fine scale (<5 km). Together, these findings suggest that antimicrobial-resistant . Typhi frequently flows between cities and then spreads highly locally, which may inform surveillance and prevention strategies.
我们对 174 株伤寒 Typhi 和 54 株副伤寒 Paratyphi A 分离株进行了全基因组测序,这些分离株是在印度那瓦西孟买分阶段引入伤寒结合疫苗的背景下通过前瞻性监测收集的。我们调查了抗生素耐药性出现和传播的时间和地理模式。我们评估了家庭之间的空间距离与分离株遗传聚类之间的关系。大多数分离株对氟喹诺酮类药物不敏感,近 20%的分离株含有≥3 种喹诺酮耐药决定区突变。两个 H58 分离株携带一个 IncX3 质粒,其中包含 bla,与头孢曲松耐药有关,这表明来自印度的头孢曲松耐药分离株多次独立进化。在 Typhi 中,我们发现了两种主要的循环流行菌株(2.2 和 4.3.1[H58]);2.2 分离株在 2007 年左右单一引入后密切相关,而 H58 分离株则多次被引入该市。分离株之间的地理距离增加与遗传聚类密切相关(优势比[OR]每公里 0.72;95%置信区间[CrI]:0.66-0.79)。这种效应在距离可达 5 公里时(OR=0.65 每公里;95%CrI:0.59-0.73)很明显,但在距离超过 5 公里时不明显(OR=1.02 每公里;95%CrI:0.83-1.26)。与非疫苗接种社区或混合配对相比,疫苗接种社区中配对分离株聚集的可能性略有降低。我们的研究结果表明,伤寒 Typhi 反复被引入那瓦西孟买,然后在当地传播,具有很强的空间遗传聚类证据。除了疫苗接种外,改善水和卫生条件的地方干预措施对于阻断传播至关重要。
在许多低收入和中等收入国家,肠热病仍然是一个主要的公共卫生问题,因为抗生素耐药性(AMR)继续出现。AMR 监测和干预规划的关键是了解伤寒的地理传播模式,但目前对此知之甚少。我们对印度那瓦西孟买引入伤寒结合疫苗前后采集的伤寒 Typhi 和副伤寒 Paratyphi A 分离株进行了全基因组测序。通过定时系统发育树,我们在那瓦西孟买发现了两种主要的伤寒 Typhi 循环株系-2.2 株系,该株系在 10 年前单一引入后扩大,而 4.3.1(H58)株系则多次从印度其他地区引入,经常含有“三重突变”,赋予高水平环丙沙星耐药性。使用贝叶斯层次统计模型,我们发现病例之间的空间距离与小尺度(<5 公里)的遗传聚类密切相关。综上所述,这些发现表明,耐药性伤寒 Typhi 经常在城市之间流动,然后在当地高度传播,这可能为监测和预防策略提供信息。