New variant of multidrug-resistant Salmonella enterica serovar Typhimurium associated with invasive disease in immunocompromised patients in Vietnam.

Authors: Mather, Alison E and Phuong, Tu Le Thi and Gao, Yunfeng and Clare, Simon and Mukhopadhyay, Subhankar and Goulding, David A and Hoang, Nhu Tran Do and Tuyen, Ha Thanh and Lan, Nguyen Phu Huong and Thompson, Corinne N and Trang, Nguyen Hoang Thu and Carrique-Mas, Juan and Tue, Ngo Tri and Campbell, James I and Rabaa, Maia A and Thanh, Duy Pham and Harcourt, Katherine and Hoa, Ngo Thi and Trung, Nguyen Vinh and Schultsz, Constance and Perron, Gabriel G and Coia, John E and Brown, Derek J and Okoro, Chinyere and Parkhill, Julian and Thomson, Nicholas R and Chau, Nguyen Van Vinh and Thwaites, Guy E and Maskell, Duncan J and Dougan, Gordon and Kenney, Linda J and Baker, Stephen

Nontyphoidal Salmonella (NTS), particularly Salmonella enterica serovar Typhimurium, is among the leading etiologic agents of bacterial enterocolitis globally and a well-characterized cause of invasive disease (iNTS) in sub-Saharan Africa. In contrast, S Typhimurium is poorly defined in Southeast Asia, a known hot spot for zoonotic disease with a recently described burden of iNTS disease. Here, we aimed to add insight into the epidemiology and potential impact of zoonotic transfer and antimicrobial resistance (AMR) in S Typhimurium associated with iNTS and enterocolitis in Vietnam. We performed whole-genome sequencing and phylogenetic reconstruction on 85 human (enterocolitis, carriage, and iNTS) and 113 animal S Typhimurium isolates isolated in Vietnam. We found limited evidence for the zoonotic transmission of S Typhimurium. However, we describe a chain of events where a pandemic monophasic variant of S Typhimurium (serovar I:4,[5],12:i:- sequence type 34 [ST34]) has been introduced into Vietnam, reacquired a phase 2 flagellum, and acquired an IncHI2 multidrug-resistant plasmid. Notably, these novel biphasic ST34 S Typhimurium variants were significantly associated with iNTS in Vietnamese HIV-infected patients. Our study represents the first characterization of novel iNTS organisms isolated outside sub-Saharan Africa and outlines a new pathway for the emergence of alternative Salmonella variants into susceptible human populations.IMPORTANCESalmonella Typhimurium is a major diarrheal pathogen and associated with invasive nontyphoid Salmonella (iNTS) disease in vulnerable populations. We present the first characterization of iNTS organisms in Southeast Asia and describe a different evolutionary trajectory from that of organisms causing iNTS in sub-Saharan Africa. In Vietnam, the globally distributed monophasic variant of Salmonella Typhimurium, the serovar I:4,[5],12:i:- ST34 clone, has reacquired a phase 2 flagellum and gained a multidrug-resistant plasmid to become associated with iNTS disease in HIV-infected patients. We document distinct communities of S Typhimurium and I:4,[5],12:i:- in animals and humans in Vietnam, despite the greater mixing of these host populations here. These data highlight the importance of whole-genome sequencing surveillance in a One Health context in understanding the evolution and spread of resistant bacterial infections. Copyright © 2018 Mather et al.

Journal: mBio
DOI: 10.1128/mBio.01056-18
Year: 2018

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