Effect of TNP on the microbiology of venous leg ulcers: a pilot study

J Wound Care. 2009 Apr;18(4):164-7. doi: 10.12968/jowc.2009.18.4.41608.


Objective: To investigate the effect of topical negative pressure, delivered using Vacuum Assisted Closure (VAC, KCI), on the microbiology of chronic, non-infected venous leg ulcers (VLUs).

Method: Patients receiving compression therapy for a chronic VLU were recruited into this prospective pilot study. The ulcer was swabbed and VAC was applied at 125mmHg continuous sub-atmospheric pressure on day 1 for six days. Standard methods for bacteriological sampling and measuring the wound surface area were applied at baseline and at the VAC dressing changes on days 3 and 6. Log median colony forming units (CFUs) per cm2 were used for statistical analyses. The bacterial species were identified.

Results: Seven patients were recruited into and completed the study. The median log10 CFU/cm2 on days 1, 3 and 6 were 3.5, 4.7 and 5.1 respectively. There was a significant increase in bacterial colonisation between days 1 and 6 (p<0.02). No change was observed in the identified microbiological species during therapy with VAC.

Conclusion: This pilot study suggests that VAC therapy increases absolute numbers of bacteria colonising non-infected leg ulcers.

Declaration of interest: KCI supplied the VAC equipment and ARANZ the SilhouetteMobile, but both had no other influence on the study.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Bacterial Infections / diagnosis
  • Bacterial Infections / etiology*
  • Bacterial Infections / prevention & control
  • Chronic Disease
  • Colony Count, Microbial
  • Cross Infection / diagnosis
  • Cross Infection / etiology*
  • Cross Infection / prevention & control
  • Female
  • Humans
  • Infection Control
  • Male
  • Middle Aged
  • Negative-Pressure Wound Therapy* / adverse effects
  • Negative-Pressure Wound Therapy* / methods
  • Pilot Projects
  • Prospective Studies
  • Risk Factors
  • Statistics, Nonparametric
  • Time Factors
  • Treatment Outcome
  • Varicose Ulcer* / complications
  • Varicose Ulcer* / therapy
  • Wound Healing
  • Wound Infection / diagnosis
  • Wound Infection / etiology*
  • Wound Infection / prevention & control