Characterization of Invasive Salmonella Serogroup C1 Infections in Mali.

Fabien J Fuche,Jasnehta Permala-Booth,Sunil Sen,Boubou Tamboura,Sharon M Tennant,Uma Onwuchekwa,Samba O Sow,Joseph Nkeze,Aliou Touré,Jennifer A Jones,Karen L Kotloff,Mamadou Sylla,Milagritos D Tapia

doi:10.4269/ajtmh.17-0508

Abstract

.Nontyphoidal Salmonella (NTS) are the leading cause of foodborne infections worldwide and a major cause of bloodstream infections in infants and HIV-infected adults in sub-Saharan Africa (SSA). Salmonella Typhimurium (serogroup B) and Salmonella Enteritidis (serogroup D) are the most common serovars in this region. However, data describing rarer invasive NTS serovars, particularly those belonging to serogroups C1 and C2, circulating in SSA are lacking. We previously conducted systematic blood culture surveillance on pediatric patients in Bamako, Mali, from 2002 to 2014, and the results showed that serovars Typhimurium and Enteritidis accounted for 32% and 36% of isolates, respectively. Here, we present data on 27 Salmonella serogroup C1 strains that were isolated during this previous study. The strains were typed by serum agglutination and multilocus sequence typing (MLST). Sixteen strains were Salmonella Paratyphi C, four were Salmonella Colindale, and two were Salmonella Virchow. Interestingly, five strains were identified as the very rare Salmonella Brazzaville using a combination of serum agglutination and flagellin gene typing. Phenotypic characterization showed that Salmonella Brazzaville produced biofilm and exhibited catalase activity, which were not statistically different from the gastroenteritis-associated Salmonella Typhimurium sequence type (ST) 19. All tested Salmonella Paratyphi C strains were poor biofilm producers and showed significantly less catalase activity than Salmonella Typhimurium ST19. Overall, our study provides insight into the Salmonella serogroup C1 serovars that cause invasive disease in infants in Mali. In addition, we show that MLST and flagellin gene sequencing, in association with traditional serum agglutination, are invaluable tools to help identify rare Salmonella serovars.

Highlights

Nontyphoidal Salmonella (NTS) are the leading cause of foodborne infections worldwide and a major cause of gastroenteritis and bloodstream infections
Twenty-seven Salmonella strains that agglutinated with O:6 antisera were previously isolated from pediatric patients who presented with fever or clinical symptoms compatible with invasive bacterial disease at l’Hopital Gabriel Tourein Bamako, Mali, between 2002 and 2014.5 Control strains for phenotypic assays included S
Of the 27 Salmonella strains that agglutinated with O:6 antisera and which were isolated from the blood of infants and children at l’Hopital Gabriel Toure, Bamako, Mali, between 2002 and 2014, all were determined to be O:6,7 by agglutination with antisera and by multilocus sequence typing (MLST) (Table 1)

Summary

Introduction

Nontyphoidal Salmonella (NTS) are the leading cause of foodborne infections worldwide and a major cause of gastroenteritis and bloodstream infections. Of the 94 million cases and 155,000 deaths attributed to NTS every year worldwide, sub-Saharan Africa (SSA) bears the highest burden with 193–338 disability-adjusted life years per 100,000 individuals, compared with 50 and 67 for Europe and North America, respectively.[1] In particular, invasive NTS (iNTS) disease, in which bacteria invade the bloodstream and cause lifethreatening disseminated infections, is a leading cause of morbidity and mortality among infants and HIV-positive adults in SSA, with up to a 30% mortality rate.[2,3]. Large studies that describe the Salmonella serovar distribution in Africa are needed to better understand the burden of iNTS disease

Methods

Results

Conclusion