Characteristics ofSalmonellaRecovered From Stools of Children Enrolled in the Global Enteric Multicenter Study

Abstract

Background The Global Enteric Multicenter Study (GEMS) determined the etiologic agents of moderate-to-severe diarrhea (MSD) in children under 5 years old in Africa and Asia. Here, we describe the prevalence and antimicrobial susceptibility of non-typhoidal Salmonella (NTS) serovars in GEMS and examine the phylogenetics of Salmonella Typhimurium ST313 isolates. Methods Salmonella isolated from children with MSD or diarrhea-free controls were identified by classical clinical microbiology and serotyped using antisera and/or whole genome sequence data. We evaluated antimicrobial susceptibility using the Kirby-Bauer disk diffusion method. Salmonella Typhimurium sequence types were determined using multi-locus sequence typing and whole genome sequencing was performed to assess the phylogeny of ST313. Results Out of 370 Salmonella-positive individuals, 190 (51.4%) were MSD cases and 180 (48.6%) were diarrhea-free controls. The most frequent Salmonella serovars identified were Salmonella Typhimurium, serogroup O:8 (C2-C3), serogroup O:6,7 (C1), Salmonella Paratyphi B Java and serogroup O:4 (B). The prevalence of NTS was low but similar across sites, regardless of age, and was similar amongst both cases and controls except in Kenya, where Salmonella Typhimurium was more commonly associated with cases than controls. Phylogenetic analysis showed that these Salmonella Typhimurium isolates, all ST313, were highly genetically related to isolates from controls. Generally, Salmonella isolates from Asia were resistant to ciprofloxacin and ceftriaxone but African isolates were susceptible to these antibiotics. Conclusion Our data confirms that NTS is prevalent, albeit at low levels, in Africa and South Asia. Our findings provide further evidence that multi-drug resistant Salmonella Typhimurium ST313 can be carried asymptomatically by humans in sub-Saharan Africa.

Isolation, Antimicrobial Resistance Phenotypes, and Virulence Genes of Bordetella bronchiseptica From Pigs in China, 2018–2020

“…Administration of antimicrobials is still one of the most effective way to control B. bronchiseptica and the other bacteria, but the emergence of drug-resistant bacteria may lead to the failure of using antibiotics in clinic (34)(35)(36). Therefore, monitoring the drug resistance profile of clinical microbiology is an important aspect in many epidemiological studies (25,37,38). In this study, we characterized the resistance phenotypes of B. bronchiseptica from pigs in China from 2018 to 2020.…”

The prospect of orally administered monoclonal secretory IgA (SIgA) antibodies to prevent enteric bacterial infections

“…While infection normally manifests as self-limiting gastroenteritis, the emergence invasive non-typhoidal STm (iNTS) isolates such as sequence type 313 (ST313) in sub-Saharan Africa capable of causing fatal systemic infections in children and immunocompromised individuals has raised alarms. 3,4,60 Furthermore, the increase of iNTS isolates carrying resistance to one or more commonly used antibiotics has prompted investigations into vaccines and alternative biologics, such as SIgA, to prevent Salmonella infections.…”

“…2 While a leading cause of MSD, the food-and water-borne pathogen, Salmonella enterica serovar Typhimurium (STm), also deserves attention because it has emerged in parts of Saharan and sub-Saharan Africa as a cause of fatal bloodstream infections in young children. 3,4 For newborns, breastfeeding is one of the most effective defenses against diarrheal diseases. [5][6][7] Colostrum and breast milk each contain an array of bioactive compounds, including cytokines, defensins, lactoferrin, and human milk oligosaccharides that collectively hinder opportunistic and pathogenic bacteria from colonizing the neonatal intestinal epithelium.…”

Case-control investigation of invasive Salmonella disease in Malawi reveals no evidence of environmental or animal transmission of invasive strains, and supports human to human transmission

“…In contrast, microbiological investigations in Kenya, based either on serotype and Pulsed Field Gel Electrophoresis or more recently WGS, found isolates in the stool of household members which were closely related to index cases, and only rarely found linked serotypes in environmental samples such as water from nearby rivers, household and market vendor food, or household animals [29,30]. The Global Enteric Multicentre Study found iNTS associated sub-types of Salmonella in the stool of 42 children with diarrhoea and 17 healthy children, highlighting the potential role of the human gut as a source of iNTS infections [31]. In The Gambia, there was no overlap observed between STs observed in iNTS cases and those observed in rectal swabs from domestic animals from the households of cases [32], while in Tanzania and Kenya, extensive sampling of "meat pathway" isolates and human disease isolates only isolated ST313 from human samples [33].…”

“…The Global Enteric Multicentre Study found iNTS associated sub-types of Salmonella in the stool of 42 children with diarrhoea and 17 healthy children, highlighting the potential role of the human gut as a source of iNTS infections [34]. In The Gambia, no overlap was observed between STs from iNTS cases and those from rectal swabs from domestic animals from the households of cases [35], while in Tanzania and Kenya, extensive sampling of “meat pathway” isolates and human disease isolates only isolated ST313 from human samples [36].…”