Cecum lymph node dendritic cells harbor slow-growing bacteria phenotypically tolerant to antibiotic treatment

Patrick Kaiser; Roland R Regoes; Tamas Dolowschiak; Sandra Y Wotzka; Jette Lengefeld; Emma Slack; Andrew J Grant; Martin Ackermann; Wolf-Dietrich Hardt

doi:10.1371/journal.pbio.1001793

Cecum lymph node dendritic cells harbor slow-growing bacteria phenotypically tolerant to antibiotic treatment

PLoS Biol. 2014 Feb 18;12(2):e1001793. doi: 10.1371/journal.pbio.1001793. eCollection 2014 Feb.

Authors

Patrick Kaiser¹, Roland R Regoes², Tamas Dolowschiak¹, Sandra Y Wotzka¹, Jette Lengefeld¹, Emma Slack¹, Andrew J Grant³, Martin Ackermann⁴, Wolf-Dietrich Hardt¹

Affiliations

¹ Institute of Microbiology, Eidgenössische Technische Hochschule ETH, Zurich, Switzerland.
² Institute of Integrative Biology, Eidgenössische Technische Hochschule ETH, Zurich, Switzerland.
³ Department of Veterinary Medicine and Cambridge Infectious Diseases Consortium, University of Cambridge, Cambridge, United Kingdom.
⁴ Department of Environmental Systems Science, ETH Zurich, and Department of Environmental Microbiology, Eawag, Switzerland.

Abstract

In vivo, antibiotics are often much less efficient than ex vivo and relapses can occur. The reasons for poor in vivo activity are still not completely understood. We have studied the fluoroquinolone antibiotic ciprofloxacin in an animal model for complicated Salmonellosis. High-dose ciprofloxacin treatment efficiently reduced pathogen loads in feces and most organs. However, the cecum draining lymph node (cLN), the gut tissue, and the spleen retained surviving bacteria. In cLN, approximately 10%-20% of the bacteria remained viable. These phenotypically tolerant bacteria lodged mostly within CD103⁺CX₃CR1⁻CD11c⁺ dendritic cells, remained genetically susceptible to ciprofloxacin, were sufficient to reinitiate infection after the end of the therapy, and displayed an extremely slow growth rate, as shown by mathematical analysis of infections with mixed inocula and segregative plasmid experiments. The slow growth was sufficient to explain recalcitrance to antibiotics treatment. Therefore, slow-growing antibiotic-tolerant bacteria lodged within dendritic cells can explain poor in vivo antibiotic activity and relapse. Administration of LPS or CpG, known elicitors of innate immune defense, reduced the loads of tolerant bacteria. Thus, manipulating innate immunity may augment the in vivo activity of antibiotics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Anti-Bacterial Agents / pharmacology*
Bacterial Load / drug effects
Cecum
Ciprofloxacin / pharmacology*
Dendritic Cells / microbiology*
Diarrhea / drug therapy
Diarrhea / immunology
Diarrhea / microbiology
Drug Resistance, Bacterial
Lipopolysaccharides / pharmacology
Lymph Nodes / immunology*
Lymph Nodes / microbiology
Mice
Mice, Inbred C57BL
Microbial Sensitivity Tests
Phenotype
Salmonella Infections / drug therapy
Salmonella Infections / immunology*
Salmonella Infections / microbiology
Salmonella typhimurium / drug effects
Salmonella typhimurium / growth & development
Salmonella typhimurium / immunology*

Substances

Anti-Bacterial Agents
Lipopolysaccharides
Ciprofloxacin

Grants and funding

W.D.H., P.K., and E.S. were supported by grants from the Swiss National Science Foundation (310030-132997/1 to W.D.H.; PZ00P3_136742 to E.S.), in part by a Sinergia grant to WDH from the SNF (CRSII3_136286) and in part from the ETH research foundation to WDH (ETH-33 12-2), R.R. was supported by a grant from the Swiss National Science Foundation (315230-130855). M.A. was supported by a grant from the Swiss National Science Foundation (31003A_130735). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.