title: Subinhibitory antibiotic therapy alters recurrent urinary tract infection pathogenesis through modulation of bacterial virulence and host immunity.
abstract: The capacity of subinhibitory levels of antibiotics to modulate bacterial virulence in vitro has recently been brought to light, raising concerns over the appropriateness of low-dose therapies, including antibiotic prophylaxis for recurrent urinary tract infection management. However, the mechanisms involved and their relevance in influencing pathogenesis have not been investigated. We characterized the ability of antibiotics to modulate virulence in the uropathogens Staphylococcus saprophyticus and Escherichia coli. Several antibiotics were able to induce the expression of adhesins critical to urothelial colonization, resulting in increased biofilm formation, colonization of murine bladders and kidneys, and promotion of intracellular niche formation. Mice receiving subinhibitory ciprofloxacin treatment were also more susceptible to severe infections and frequent recurrences. A ciprofloxacin prophylaxis model revealed this strategy to be ineffective in reducing recurrences and worsened infection by creating larger intracellular reservoirs at higher frequencies. Our study indicates that certain agents used for antibiotic prophylaxis have the potential to complicate infections.
  
  
  OBJECTIVE
  Antibiotics are the mainstay treatment for bacterial infections; however, evidence is emerging that argues these agents may have off-target effects if sublethal concentrations are present. Most studies have focused on changes occurring in vitro, leaving questions regarding the clinical relevance in vivo. We utilized a murine urinary tract infection model to explore the potential impact of low-dose antibiotics on pathogenesis. Using this model, we showed that subinhibitory antibiotics prime uropathogens for adherence and invasion of murine urothelial tissues. These changes in initial colonization promoted the establishment of chronic infection. Furthermore, treatment of chronically infected mice with subtherapeutic ciprofloxacin served to exacerbate infection. A part of these changes was thought to be due to suppression of mucosal immunity, as demonstrated through reductions in cytokine secretion and migration of leukocytes into the urinary tract. This work identifies novel risk factors associated with antibiotic therapy when dosing strategies fall below subtherapeutic levels.
authors.affiliation: lee.goneau@gmail.com.
authors.forename: Lee W
authors.initials: LW
authors.lastname: Goneau
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hannan
authors.affiliation: Lawson Health Research Institute, St. Joseph's Hospital, London, Ontario, Canada.
authors.forename: Roderick A
authors.initials: RA
authors.lastname: MacPhee
authors.affiliation: Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Drew J
authors.initials: DJ
authors.lastname: Schwartz
authors.affiliation: Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Jean M
authors.initials: JM
authors.lastname: Macklaim
authors.affiliation: Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Gloor
authors.forename: Hassan
authors.initials: H
authors.lastname: Razvi
authors.forename: Gregor
authors.initials: G
authors.lastname: Reid
authors.affiliation: Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hultgren
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Burton
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001422:Bacterial Adhesion; D001424:Bacterial Infections / Q000188:drug therapy* / Q000276:immunology; D018441:Biofilms / Q000254:growth & development; D004195:Disease Models, Animal; D004358:Drug Therapy / Q000379:methods; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development* / Q000276:immunology / Q000502:physiology; D005260:Female; D007668:Kidney / Q000382:microbiology; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D012008:Recurrence; D057790:Staphylococcus saprophyticus / Q000187:drug effects* / Q000254:growth & development* / Q000276:immunology / Q000502:physiology; D001743:Urinary Bladder / Q000382:microbiology; D014552:Urinary Tract Infections / Q000188:drug therapy* / Q000276:immunology; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents
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