Isolation and characterization of macrophage adapted Salmonella Typhimurium persister clones

Lotte Jelsbak, Maja Marie Sørensen, Kasper Lind Lauridsen

Publikation: KonferencebidragKonferenceabstrakt til konferenceForskning


Background: Cultured macrophages are frequently used to investigate Salmonella-host interactions on a population scale. However, in recent years it has been documented that several sub-populations of intracellular Salmonella with distinct growth phenotypes develop during infection of host cells (Helaine and co-workers). Specifically, a high level of intracellular dormant bacteria (persisters) was reported. These results show that Salmonella undergo adaptive changes in response to the host-environment at a regulatory single-cell level; however, the extent to which individual Salmonella sub-populations adapt at a genetic level remains to be investigated.
Aims, methods and results: The aim of this study was to investigate genetic changes of Salmonella in response to brief exposures to the host environment, and in particular investigate genetic adaptation within the dormant population. Cultured macrophages were infected with Salmonella bacteria for 30 minutes. Persister bacteria were isolated by plating on ampicillin, recovered by addition of penicillinase and cultured for a new round of infection. For every round of infection we observed a gradual increase in the number of persister-bacteria isolated from the macrophages, indicating genetic adaptation to the host environment. After 7 rounds, we randomly picked 6 clones and subjected these to whole genome sequencing. The six clones were almost identical exhibiting the same mutations. A total of 5 mutations were identified representing both SNPs and in-dels and synonymous and non-synonymous types. Of these, one mutation was an in-frame 15 bp deletion resulting in a 5 amino acid shortening of a conserved hypothetical protein that has been implicated in host-interactions. Another mutation was a 161 bp deletion fusing two genes of a hypothetical ABC-transporter operon in-frame, resulting in expression a larger protein. We are presently investigating the contributions of these mutations to Salmonella-host interactions.
Conclusions: In the present project we have investigated genetic adaptation to the host-environment in the intracellular persister population of Salmonella Typhimurium. We can report that even during brief exposures, Salmonella undergo genetic changes that may affect host-interactions. We are presently investigating this possibility.
StatusUdgivet - 2018
BegivenhedChallenges and new concepts in antibiotics research Conference - Pasteur Institute, Paris, Frankrig
Varighed: 19 mar. 201821 mar. 2018


KonferenceChallenges and new concepts in antibiotics research Conference
LokationPasteur Institute
AndetAntimicrobial resistance threatens the prevention and treatment of an increasing number of bacterial infections. To avoid a post antibiotics crisis, innovations and breakthrough ideas are urgently needed in all areas of antibiotics research conducted by academics, clinicians or industrials and new prevention and control measurements by public health agencies and politics have to be developed.<br/><br/>The Challenges and new concepts in antibiotics research conference will bring together speakers and experts who are leaders in the field of antibiotics resistance and the development of new molecules and alternative strategies. It will provide abundant opportunities for networking and exchange of information between senior scientists and professionals, new investigators and students, in a pleasant and informal setting.<br/>This meeting is organized under the umbrella of the LabEx project “Integrated Biology of Infectious Diseases” (IBEID).

Citer dette