Genetic variation in the MacAB-TolC efflux pump influences pathogenesis of invasive <i>Salmonella</i> isolates from Africa

Honeycutt, Jared D, Wenner, Nicolas, Li, Yan ORCID: 0000-0002-7480-9545, Brewer, Susan M, Massis, Liliana M, Brubaker, Sky W, Chairatana, Phoom, Owen, Sian V, Canals, Rocio, Hinton, Jay CD ORCID: 0000-0003-2671-6026
et al (show 1 more authors) (2020) Genetic variation in the MacAB-TolC efflux pump influences pathogenesis of invasive <i>Salmonella</i> isolates from Africa. PLOS PATHOGENS, 16 (8). e1008763-.

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The various sub-species of Salmonella enterica cause a range of disease in human hosts. The human-adapted Salmonella enterica serovar Typhi enters the gastrointestinal tract and invades systemic sites to cause enteric (typhoid) fever. In contrast, most non-typhoidal serovars of Salmonella are primarily restricted to gut tissues. Across Africa, invasive non-typhoidal Salmonella (iNTS) have emerged with an ability to spread beyond the gastrointestinal tract and cause systemic bloodstream infections with increased morbidity and mortality. To investigate this evolution in pathogenesis, we compared the genomes of African iNTS isolates with other Salmonella enterica serovar Typhimurium and identified several macA and macB gene variants unique to African iNTS. MacAB forms a tripartite efflux pump with TolC and is implicated in Salmonella pathogenesis. We show that macAB transcription is upregulated during macrophage infection and after antimicrobial peptide exposure, with macAB transcription being supported by the PhoP/Q two-component system. Constitutive expression of macAB improves survival of Salmonella in the presence of the antimicrobial peptide C18G. Furthermore, these macAB variants affect replication in macrophages and influence fitness during colonization of the murine gastrointestinal tract. Importantly, the infection outcome resulting from these macAB variants depends upon both the Salmonella Typhimurium genetic background and the host gene Nramp1, an important determinant of innate resistance to intracellular bacterial infection. The variations we have identified in the MacAB-TolC efflux pump in African iNTS may reflect evolution within human host populations that are compromised in their ability to clear intracellular Salmonella infections.

Item Type: Article
Uncontrolled Keywords: Macrophages, Animals, Mice, Inbred C57BL, Mice, Salmonella typhimurium, Salmonella Infections, Animal, Colitis, Disease Models, Animal, Bacterial Proteins, ATP-Binding Cassette Transporters, DNA Mutational Analysis, Virus Replication, Cell Lineage, Genetic Variation
Depositing User: Symplectic Admin
Date Deposited: 10 Sep 2020 08:45
Last Modified: 14 Oct 2023 11:27
DOI: 10.1371/journal.ppat.1008763
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