ABSTRACT
BACKGROUND: Invasive non-typhoidal Salmonella (iNTS) is one of the leading causes of bacteraemia in sub-Saharan Africa. We aimed to provide a better understanding of the genetic characteristics and transmission patterns associated with multi-drug resistant (MDR) iNTS serovars across the continent. METHODS: A total of 166 iNTS isolates collected from a multi-centre surveillance in 10 African countries (2010-2014) and a fever study in Ghana (2007-2009) were genome sequenced to investigate the geographical distribution, antimicrobial genetic determinants and population structure of iNTS serotypes-genotypes. Phylogenetic analyses were conducted in the context of the existing genomic frameworks for various iNTS serovars. Population-based incidence of MDR-iNTS disease was estimated in each study site. RESULTS: Salmonella Typhimurium sequence-type (ST) 313 and Salmonella Enteritidis ST11 were predominant, and both exhibited high frequencies of MDR; Salmonella Dublin ST10 was identified in West Africa only. Mutations in the gyrA gene (fluoroquinolone resistance) were identified in S. Enteritidis and S. Typhimurium in Ghana; an ST313 isolate carrying blaCTX-M-15 was found in Kenya. International transmission of MDR ST313 (lineage II) and MDR ST11 (West African clade) was observed between Ghana and neighbouring West African countries. The incidence of MDR-iNTS disease exceeded 100/100 000 person-years-of-observation in children aged <5 years in several West African countries. CONCLUSIONS: We identified the circulation of multiple MDR iNTS serovar STs in the sampled sub-Saharan African countries. Investment in the development and deployment of iNTS vaccines coupled with intensified antimicrobial resistance surveillance are essential to limit the impact of these pathogens in Africa.
Subject(s)
Pharmaceutical Preparations , Salmonella typhimurium , Child , Genomics , Humans , Kenya , Phylogeny , Salmonella typhimurium/geneticsABSTRACT
A qnrB2 determinant was described for a new complex sul1-type integron from Salmonella enterica serovar Keurmassar. The genetic structure contained two class 1 integrons surrounding two common regions (CRs) separated by a partial 3' conserved segment. The qnrB2 gene is adjacent to the first CR.
Subject(s)
Escherichia coli Proteins/genetics , Integrons/genetics , Quinolones/pharmacology , Salmonella enterica/drug effects , Salmonella enterica/genetics , Base Sequence , Conjugation, Genetic , Drug Resistance, Bacterial , Molecular Sequence Data , Open Reading Frames , Polymerase Chain Reaction , Salmonella enterica/isolation & purificationABSTRACT
Ten enteroinvasive (EIEC) and 25 enteroaggregative (EaggEC) E. coli strains isolated from Senegalese patients were analyzed for their integron content. All strains were resistant to at least two antibiotics. Four EIEC and 15 EaggEC were found to carry a class 1 integron. An identical integron carrying a single dfrA5 cassette, conferring resistance to trimethoprim, was identified in all four EIEC strains. Five EaggEC strains harbored an integron with a single cassette, dfrA7, while the remaining 10 strains carried two integrons, one with a single cassette, aadA1a conferring resistance to streptomycin and spectinomycin, and the second one bearing two cassettes, dfrA13 and oxa5, the later being a beta-lactam resistance cassette. The presence of these integrons is worrying, because trimethoprim is largely used for diarrheal disease therapy in Africa. Thus, the presence of integrons in diarrheagenic strains is of public health importance because a limited number of antibiotics are available in developing countries.
