In vivo efficacy of the combination of ciprofloxacin and cefotaxime against Vibrio vulnificus sepsis

PLoS One. 2014 Jun 30;9(6):e101118. doi: 10.1371/journal.pone.0101118. eCollection 2014.

Abstract

Objectives: The in vivo efficacy of a cefotaxime-ciprofloxacin combination against Vibrio vulnificus and the effects on rtxA1 expression of commonly used antibiotics are unknown.

Methods: In vitro time-kill studies were performed to evaluate synergism. Female BALB/c mice were injected subcutaneously with 1×10(7) or 1×10(8) cfu of V. vulnificus. Antibiotic therapy was initiated at 2 h after inoculation in the following four therapy groups: cefotaxime; ciprofloxacin; cefotaxime-plus-ciprofloxacin; and cefotaxime-plus-minocycline. The cytotoxicity of V. vulnificus for HeLa cells was measured using the lactate dehydrogenase assay; rtxA1 transcription was measured in a transcriptional reporter strain using a β-galactosidase assay.

Results: In vitro time-kill assays exhibited synergism between cefotaxime and ciprofloxacin. In the animal experiments, the 96-h survival rate for the cefotaxime-plus-ciprofloxacin group (85%; 17/20) was significantly higher than that of the cefotaxime-plus-minocycline (35%; 7/20) and cefotaxime alone (0%; 0/20) groups (P<0.05 for both). Bacterial counts in the liver and spleen were significantly lower in the cefotaxime-plus-ciprofloxacin group 24 and 48 h after treatment, relative to the other groups. At sub-inhibitory concentrations, ciprofloxacin inhibited more effectively rtxA1 transcription and mammalian cell cytotoxicity than either minocycline or cefotaxime (P<0.05 for both).

Conclusions: Ciprofloxacin is more effective at reducing rtxA1 transcription and subsequent cytotoxicity than either minocycline or cefotaxime, and the combination of ciprofloxacin and cefotaxime was more effective in clearing V. vulnificus in vivo than previously used regimens. These data suggest that the combination of ciprofloxacin and cefotaxime is an effective option for the treatment of V. vulnificus sepsis in humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Bacterial Toxins / genetics
  • Cefotaxime / pharmacology
  • Cefotaxime / therapeutic use*
  • Cell Death / drug effects
  • Ciprofloxacin / pharmacology
  • Ciprofloxacin / therapeutic use*
  • Colony Count, Microbial
  • Drug Therapy, Combination
  • Female
  • HeLa Cells
  • Humans
  • Mice, Inbred BALB C
  • Microbial Sensitivity Tests
  • Sepsis / drug therapy*
  • Sepsis / microbiology*
  • Survival Analysis
  • Time Factors
  • Transcription, Genetic / drug effects
  • Vibrio Infections / drug therapy*
  • Vibrio Infections / microbiology*
  • Vibrio vulnificus / drug effects
  • Vibrio vulnificus / growth & development
  • Vibrio vulnificus / physiology*

Substances

  • Anti-Bacterial Agents
  • Bacterial Toxins
  • Ciprofloxacin
  • Cefotaxime

Grants and funding

This work was supported by a grant from the Research Institute of Medical Sciences, Chonnam National University (2011-CURIMS-DR005). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.