Invasive Non-typhoidal Salmonella Infections in Asia: Clinical Observations, Disease Outcome and Dominant Serovars from an Infectious Disease Hospital in Vietnam.

Nguyen Phu Huong Lan,Stephen Baker,Guy E Thwaites,Tu Le Thi Phuong,Florian Marks,Se Eun Park,Le Thuy,Alison E Mather,Hien Nguyen Huu,Nguyen Van Vinh Chau,Corinne N Thompson,Pamela L C Small

doi:10.1371/journal.pntd.0004857

Abstract

Invasive non-typhoidal Salmonella (iNTS) infections are now a well-described cause of morbidity and mortality in children and HIV-infected adults in sub-Saharan Africa. In contrast, the epidemiology and clinical manifestations of iNTS disease in Asia are not well documented. We retrospectively identified >100 cases of iNTS infections in an infectious disease hospital in Southern Vietnam between 2008 and 2013. Clinical records were accessed to evaluate demographic and clinical factors associated with iNTS infection and to identify risk factors associated with death. Multi-locus sequence typing and antimicrobial susceptibility testing was performed on all organisms. Of 102 iNTS patients, 71% were HIV-infected, >90% were adults, 71% were male and 33% reported intravenous drug use. Twenty-six/92 (28%) patients with a known outcome died; HIV infection was significantly associated with death (p = 0.039). S. Enteritidis (Sequence Types (ST)11) (48%, 43/89) and S. Typhimurium (ST19, 34 and 1544) (26%, 23/89) were the most commonly identified serovars; S. Typhimurium was significantly more common in HIV-infected individuals (p = 0.003). Isolates from HIV-infected patients were more likely to exhibit reduced susceptibility against trimethoprim-sulfamethoxazole than HIV-negative patients (p = 0.037). We conclude that iNTS disease is a severe infection in Vietnam with a high mortality rate. As in sub-Saharan Africa, HIV infection was a risk factor for death, with the majority of the burden in this population found in HIV-infected adult men.

Highlights

Infections with organisms belonging the bacterial genus Salmonella are associated with a range of disease syndromes in humans
We evaluated over 100 Invasive non-typhoidal Salmonella (iNTS) cases from an infectious disease hospital in southern Vietnam admitted between 2008– 2013
We used hospital records to determine the clinical features of iNTS disease and to identify risk factors associated with death and performed typing of the isolated organisms

Summary

Introduction

Infections with organisms belonging the bacterial genus Salmonella are associated with a range of disease syndromes in humans. The vast majority of the Salmonella subspecies I serovars are not commonly associated with systemic disease in humans and are referred to as non-typhoidal Salmonella (NTS). In addition to the common diarrheal clinical syndrome induced by NTS organisms in humans, invasive (bloodstream) NTS (iNTS) disease can occur in specific populations [3,4]. INTS disease, which is most commonly caused by the Salmonella serovars Typhimurium and Enteritidis [5,6], is associated with an aggressive systemic infection that loosely resembles typhoid fever [2,4,7]. There are an approximately 1.9 million cases of iNTS disease in sub-Saharan Africa annually, with an overall estimated incidence rate of 227 per 100,000 population [8], and 175–388 and 2,000–7,500 per 100,000 population in children 3–5 years of age and HIV-infected individuals, respectively [3,9,10,11,12,13,14]

Results

Discussion

Conclusion